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Search found 152 results on 7 pages for 'getmethod'.

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  • BindException/Too many file open while using HttpClient under load

    - by Langali
    I have got 1000 dedicated Java threads where each thread polls a corresponding url every one second. public class Poller { public static Node poll(Node node) { GetMethod method = null; try { HttpClient client = new HttpClient(new SimpleHttpConnectionManager(true)); ...... } catch (IOException ex) { ex.printStackTrace(); } finally { method.releaseConnection(); } } } The threads are run every one second: for (int i=0; i <1000; i++) { MyThread thread = threads.get(i) // threads is a static field if(thread.isAlive()) { // If the previous thread is still running, let it run. } else { thread.start(); } } The problem is if I run the job every one second I get random exceptions like these: java.net.BindException: Address already in use INFO httpclient.HttpMethodDirector: I/O exception (java.net.BindException) caught when processing request: Address already in use INFO httpclient.HttpMethodDirector: Retrying request But if I run the job every 2 seconds or more, everything runs fine. I even tried shutting down the instance of SimpleHttpConnectionManager() using shutDown() with no effect. If I do netstat, I see thousands of TCP connections in TIME_WAIT state, which means they are have been closed and are clearing up. So to limit the no of connections, I tried using a single instance of HttpClient and use it like this: public class MyHttpClientFactory { private static MyHttpClientFactory instance = new HttpClientFactory(); private MultiThreadedHttpConnectionManager connectionManager; private HttpClient client; private HttpClientFactory() { init(); } public static HttpClientFactory getInstance() { return instance; } public void init() { connectionManager = new MultiThreadedHttpConnectionManager(); HttpConnectionManagerParams managerParams = new HttpConnectionManagerParams(); managerParams.setMaxTotalConnections(1000); connectionManager.setParams(managerParams); client = new HttpClient(connectionManager); } public HttpClient getHttpClient() { if (client != null) { return client; } else { init(); return client; } } } However after running for exactly 2 hours, it starts throwing 'too many open files' and eventually cannot do anything at all. ERROR java.net.SocketException: Too many open files INFO httpclient.HttpMethodDirector: I/O exception (java.net.SocketException) caught when processing request: Too many open files INFO httpclient.HttpMethodDirector: Retrying request I should be able to increase the no of connections allowed and make it work, but I would just be prolonging the evil. Any idea what is the best practise to use HttpClient in a situation like above? Btw, I am still on HttpClient3.1.

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  • Can't find method in the activity

    - by Synesso
    I'm starting with Scala + Android. I'm trying to wire a button action to a button without the activity implementing View.OnClickListener. The button click fails at runtime because the method cannot be found. The document I'm working through says that I need only declare a public void method taking a View on the action, and use that method name in the layout. What have I done wrong? MainActivity.scala package net.badgerhunt.hwa import android.app.Activity import android.os.Bundle import android.widget.Button import android.view.View import java.util.Date class MainActivity extends Activity { override def onCreate(savedInstanceState: Bundle) = { super.onCreate(savedInstanceState) setContentView(R.layout.main) } def calculate(button: View): Unit = println("calculating with %s ...".format(button)) } res/layout/main.xml <?xml version="1.0" encoding="utf-8"?> <Button xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/button" android:text="" android:onClick="calculate" android:layout_width="fill_parent" android:layout_height="fill_parent"/> the failure onclick D/AndroidRuntime( 362): Shutting down VM W/dalvikvm( 362): threadid=3: thread exiting with uncaught exception (group=0x4001b188) E/AndroidRuntime( 362): Uncaught handler: thread main exiting due to uncaught exception E/AndroidRuntime( 362): java.lang.IllegalStateException: Could not find a method calculate(View) in the activity E/AndroidRuntime( 362): at android.view.View$1.onClick(View.java:2020) E/AndroidRuntime( 362): at android.view.View.performClick(View.java:2364) E/AndroidRuntime( 362): at android.view.View.onTouchEvent(View.java:4179) E/AndroidRuntime( 362): at android.widget.TextView.onTouchEvent(TextView.java:6540) E/AndroidRuntime( 362): at android.view.View.dispatchTouchEvent(View.java:3709) E/AndroidRuntime( 362): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) E/AndroidRuntime( 362): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) E/AndroidRuntime( 362): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) E/AndroidRuntime( 362): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659) E/AndroidRuntime( 362): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107) E/AndroidRuntime( 362): at android.app.Activity.dispatchTouchEvent(Activity.java:2061) E/AndroidRuntime( 362): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643) E/AndroidRuntime( 362): at android.view.ViewRoot.handleMessage(ViewRoot.java:1691) E/AndroidRuntime( 362): at android.os.Handler.dispatchMessage(Handler.java:99) E/AndroidRuntime( 362): at android.os.Looper.loop(Looper.java:123) E/AndroidRuntime( 362): at android.app.ActivityThread.main(ActivityThread.java:4363) E/AndroidRuntime( 362): at java.lang.reflect.Method.invokeNative(Native Method) E/AndroidRuntime( 362): at java.lang.reflect.Method.invoke(Method.java:521) E/AndroidRuntime( 362): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) E/AndroidRuntime( 362): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) E/AndroidRuntime( 362): at dalvik.system.NativeStart.main(Native Method) E/AndroidRuntime( 362): Caused by: java.lang.NoSuchMethodException: calculate E/AndroidRuntime( 362): at java.lang.ClassCache.findMethodByName(ClassCache.java:308) E/AndroidRuntime( 362): at java.lang.Class.getMethod(Class.java:1014) E/AndroidRuntime( 362): at android.view.View$1.onClick(View.java:2017) E/AndroidRuntime( 362): ... 20 more

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  • .Net Dynamically Load DLL

    - by hermiod
    I am trying to write some code that will allow me to dynamically load DLLs into my application, depending on an application setting. The idea is that the database to be accessed is set in the application settings and then this loads the appropriate DLL and assigns it to an instance of an interface for my application to access. This is my code at the moment: Dim SQLDataSource As ICRDataLayer Dim ass As Assembly = Assembly. _ LoadFrom("M:\MyProgs\WebService\DynamicAssemblyLoading\SQLServer\bin\Debug\SQLServer.dll") Dim obj As Object = ass.CreateInstance(GetType(ICRDataLayer).ToString, True) SQLDataSource = DirectCast(obj, ICRDataLayer) MsgBox(SQLDataSource.ModuleName & vbNewLine & SQLDataSource.ModuleDescription) I have my interface (ICRDataLayer) and the SQLServer.dll contains an implementation of this interface. I just want to load the assembly and assign it to the SQLDataSource object. The above code just doesn't work. There are no exceptions thrown, even the Msgbox doesn't appear. I would've expected at least the messagebox appearing with nothing in it, but even this doesn't happen! Is there a way to determine if the loaded assembly implements a specific interface. I tried the below but this also doesn't seem to do anything! For Each loadedType As Type In ass.GetTypes If GetType(ICRDataLayer).IsAssignableFrom(loadedType) Then Dim obj1 As Object = ass.CreateInstance(GetType(ICRDataLayer).ToString, True) SQLDataSource = DirectCast(obj1, ICRDataLayer) End If Next EDIT: New code from Vlad's examples: Module CRDataLayerFactory Sub New() End Sub ' class name is a contract, ' should be the same for all plugins Private Function Create() As ICRDataLayer Return New SQLServer() End Function End Module Above is Module in each DLL, converted from Vlad's C# example. Below is my code to bring in the DLL: Dim SQLDataSource As ICRDataLayer Dim ass As Assembly = Assembly. _ LoadFrom("M:\MyProgs\WebService\DynamicAssemblyLoading\SQLServer\bin\Debug\SQLServer.dll") Dim factory As Object = ass.CreateInstance("CRDataLayerFactory", True) Dim t As Type = factory.GetType Dim method As MethodInfo = t.GetMethod("Create") Dim obj As Object = method.Invoke(factory, Nothing) SQLDataSource = DirectCast(obj, ICRDataLayer) EDIT: Implementation based on Paul Kohler's code Dim file As String For Each file In Directory.GetFiles(baseDir, searchPattern, SearchOption.TopDirectoryOnly) Dim assemblyType As System.Type For Each assemblyType In Assembly.LoadFrom(file).GetTypes Dim s As System.Type() = assemblyType.GetInterfaces For Each ty As System.Type In s If ty.Name.Contains("ICRDataLayer") Then MsgBox(ty.Name) plugin = DirectCast(Activator.CreateInstance(assemblyType), ICRDataLayer) MessageBox.Show(plugin.ModuleName) End If Next I get the following error with this code: Unable to cast object of type 'SQLServer.CRDataSource.SQLServer' to type 'DynamicAssemblyLoading.ICRDataLayer'. The actual DLL is in a different project called SQLServer in the same solution as my implementation code. CRDataSource is a namespace and SQLServer is the actual class name of the DLL. The SQLServer class implements ICRDataLayer, so I don't understand why it wouldn't be able to cast it. Is the naming significant here, I wouldn't have thought it would be.

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  • CLR 4.0 inlining policy? (maybe bug with MethodImplOptions.NoInlining)

    - by ControlFlow
    I've testing some new CLR 4.0 behavior in method inlining (cross-assembly inlining) and found some strage results: Assembly ClassLib.dll: using System.Diagnostics; using System; using System.Reflection; using System.Security; using System.Runtime.CompilerServices; namespace ClassLib { public static class A { static readonly MethodInfo GetExecuting = typeof(Assembly).GetMethod("GetExecutingAssembly"); public static Assembly Foo(out StackTrace stack) // 13 bytes { // explicit call to GetExecutingAssembly() stack = new StackTrace(); return Assembly.GetExecutingAssembly(); } public static Assembly Bar(out StackTrace stack) // 25 bytes { // reflection call to GetExecutingAssembly() stack = new StackTrace(); return (Assembly) GetExecuting.Invoke(null, null); } public static Assembly Baz(out StackTrace stack) // 9 bytes { stack = new StackTrace(); return null; } public static Assembly Bob(out StackTrace stack) // 13 bytes { // call of non-inlinable method! return SomeSecurityCriticalMethod(out stack); } [SecurityCritical, MethodImpl(MethodImplOptions.NoInlining)] static Assembly SomeSecurityCriticalMethod(out StackTrace stack) { stack = new StackTrace(); return Assembly.GetExecutingAssembly(); } } } Assembly ConsoleApp.exe using System; using ClassLib; using System.Diagnostics; class Program { static void Main() { Console.WriteLine("runtime: {0}", Environment.Version); StackTrace stack; Console.WriteLine("Foo: {0}\n{1}", A.Foo(out stack), stack); Console.WriteLine("Bar: {0}\n{1}", A.Bar(out stack), stack); Console.WriteLine("Baz: {0}\n{1}", A.Baz(out stack), stack); Console.WriteLine("Bob: {0}\n{1}", A.Bob(out stack), stack); } } Results: runtime: 4.0.30128.1 Foo: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null at ClassLib.A.Foo(StackTrace& stack) at Program.Main() Bar: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null at ClassLib.A.Bar(StackTrace& stack) at Program.Main() Baz: at Program.Main() Bob: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null at Program.Main() So questions are: Why JIT does not inlined Foo and Bar calls as Baz does? They are lower than 32 bytes of IL and are good candidates for inlining. Why JIT inlined call of Bob and inner call of SomeSecurityCriticalMethod that is marked with the [MethodImpl(MethodImplOptions.NoInlining)] attribute? Why GetExecutingAssembly returns a valid assembly when is called by inlined Baz and SomeSecurityCriticalMethod methods? I've expect that it performs the stack walk to detect the executing assembly, but stack will contains only Program.Main() call and no methods of ClassLib assenbly, to ConsoleApp should be returned.

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  • Calling function dynamically by using Reflection

    - by Alaa'
    Hi, I'm generating dll files contain code like the following example : // using System; using System.Collections; using System.Xml; using System.IO; using System.Windows.Forms; namespace CSharpScripter { public class TestClass : CSharpScripter.Command { private int i=1; private int j=2; public int k=3; public TestClass6() { } public void display (int i,int j,int k) { string a = null; a= k.ToString(); string a1 = null; a1= this.i.ToString(); string a2 = null; a2= j.ToString(); MessageBox.Show(" working! "+ "k="+ a +" i="+a1 + " j="+ a2); } public void setValues(int i,int j,int k1) { this.i=i; this.j=j; k=k1; } // I'm compiling the pervious code, then I execute an object from the dll file. So, in the second part of the code ( Executing part), I'm just calling the execute function, It contains a call for a function, I named here: display. For that I need to set values in the declaration by a setValue function. I want it to been called dynamically (setValues ), which has declaration like : public void(Parameter[] parameters) { //some code block here } For this situation I used Reflection. // Type objectType = testClass.GetType(); MethodInfo members = objectType.GetMethod("setValues"); ParameterInfo[] parameters = members.GetParameters(); For) int t = 0; t < parameters.Length; t++) { If (parameters[t]. ParameterType == typeof()) { object value = this.textBox2.Text; parameters.SetValue)Convert.ChangeType(value,parameters[t].ParameterType), t); } } // But it throws an casting error" Object cannot be stored in an array of this type." at last line, in first parameter for (setValue) methode. What is the problem here? And How I can call the method Dynamically after the previous code, by( Invoke) or is there a better way? Thanks.

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  • Can I call make runtime decided method calls in Java?

    - by Catalin Marin
    I know there is an invoke function that does the stuff, I am overall interested in the "correctness" of using such a behavior. My issue is this: I have a Service Object witch contains methods which I consider services. What I want to do is alter the behavior of those services without later intrusion. For example: class MyService { public ServiceResponse ServeMeDonuts() { do stuff... return new ServiceResponse(); } after 2 months I find out that I need to offer the same service to a new client app and I also need to do certain extra stuff like setting a flag, or make or updating certain data, or encode the response differently. What I can do is pop it up and throw down some IFs. In my opinion this is not good as it means interaction with tested code and may result in un wanted behaviour for the previous service clients. So I come and add something to my registry telling the system that the "NewClient" has a different behavior. So I'll do something like this: public interface Behavior { public void preExecute(); public void postExecute(); } public class BehaviorOfMyService implements Behavior{ String method; String clientType; public void BehaviorOfMyService(String method,String clientType) { this.method = method; this.clientType = clientType; } public void preExecute() { Method preCall = this.getClass().getMethod("pre" + this.method + this.clientType); if(preCall != null) { return preCall.invoke(); } return false; } ...same for postExecute(); public void preServeMeDonutsNewClient() { do the stuff... } } when the system will do something like this if(registrySaysThereIs different behavior set for this ServiceObject) { Class toBeCalled = Class.forName("BehaviorOf" + usedServiceObjectName); Object instance = toBeCalled.getConstructor().newInstance(method,client); instance.preExecute(); ....call the service... instance.postExecute(); .... } I am not particularly interested in correctness of code as in correctness of thinking and approach. Actually I have to do this in PHP, witch I see as a kind of Pop music of programming which I have to "sing" for commercial reasons, even though I play POP I really want to sing by the book, so putting aside my more or less inspired analogy I really want to know your opinion on this matter for it's practical necessity and technical approach. Thanks

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  • Loading jar file using JCL(JarClassLoader ) : classpath in manifest is ignored ..

    - by Xinus
    I am trying to load jar file using JCL using following code FileInputStream fis = new FileInputStream(new File( "C:\\Users\\sunils\\glassfish-tests\\working\\test.jar") ); JarClassLoader jc = new JarClassLoader( ); jc.add(fis); Class main = jc.loadClass( "highmark.test.Main" ); String[] str={}; main.getMethod("test").invoke(null);//.getDeclaredMethod("main",String[].class).invoke(null,str); fis.close(); But when I try to run this program I get Exception as Exception in thread "main" java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at Main.main(Main.java:21) Caused by: java.lang.RuntimeException: Embedded startup not found, classpath is probably incomplete at org.glassfish.api.embedded.Server.<init>(Server.java:292) at org.glassfish.api.embedded.Server.<init>(Server.java:75) at org.glassfish.api.embedded.Server$Builder.build(Server.java:185) at org.glassfish.api.embedded.Server$Builder.build(Server.java:167) at highmark.test.Main.test(Main.java:33) ... 5 more According to this it is not able to locate class, But when I run the jar file explicitly it runs fine. It seems like JCL is ignoring other classes present in the jar file, MANIFEST.MF file in jar file shows: Manifest-Version: 1.0 Class-Path: . Main-Class: highmark.test.Main It seems to be ignoring Class-Path: . , This jar file runs fine when I run it using Java explicitly, This is just a test, in reality this jar file is coming as a InputStream and it cannot be stored in filesystem, How can I overcome this problem , Is there any workaround ? Thanks for any help . UNDATE: Here is a jar Main class : package highmark.test; import org.glassfish.api.embedded.*; import java.io.*; import org.glassfish.api.deployment.*; import com.sun.enterprise.universal.io.FileUtils; public class Main { public static void main(String[] args) throws IOException, LifecycleException, ClassNotFoundException { test(); } public static void test() throws IOException, LifecycleException, ClassNotFoundException{ Server.Builder builder = new Server.Builder("test"); Server server = builder.build(); server.createPort(8080); ContainerBuilder containerBuilder = server.createConfig(ContainerBuilder.Type.web); server.addContainer(containerBuilder); server.start(); File war=new File("C:\\Users\\sunils\\maventests\\simple-webapp\\target\\simple-webapp.war");//(File) inputStream.readObject(); EmbeddedDeployer deployer = server.getDeployer(); DeployCommandParameters params = new DeployCommandParameters(); params.contextroot = "simple"; deployer.deploy(war, params); } }

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  • Different behavior of reflected generic delegates with and without debugger

    - by Andrew_B
    Hello. We have encountered some strange things while calling reflected generic delegates. In some cases with attatched debuger we can make impossible call, while without debugger we cannot catch any exception and application fastfails. Here is the code: using System; using System.Windows.Forms; using System.Reflection; namespace GenericDelegate { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private delegate Class2 Delegate1(); private void button1_Click(object sender, EventArgs e) { MethodInfo mi = typeof (Class1<>).GetMethod("GetClass", BindingFlags.NonPublic | BindingFlags.Static); if (mi != null) { Delegate1 del = (Delegate1) Delegate.CreateDelegate(typeof (Delegate1), mi); MessageBox.Show("1"); try { del(); } catch (Exception) { MessageBox.Show("No, I can`t catch it"); } MessageBox.Show("2"); mi.Invoke(null, new object[] {});//It's Ok, we'll get exception here MessageBox.Show("3"); } } class Class2 { } class Class1<T> : Class2 { internal static Class2 GetClass() { Type type = typeof(T); MessageBox.Show("Type name " + type.FullName +" Type: " + type + " Assembly " + type.Assembly); return new Class1<T>(); } } } } There are two problems: Behavior differs with debugger and without You cannot catch this error without debugger by clr tricks. It's just not the clr exception. There are memory acces vialation, reading zero pointer inside of internal code. Use case: You develop something like plugins system for your app. You read external assembly, find suitable method in some type, and execute it. And we just forgot about that we need to check up is the type generic or not. Under VS (and .net from 2.0 to 4.0) everything works fine. Called function does not uses static context of generic type and type parameters. But without VS application fails with no sound. We even cannot identify call stack attaching debuger. Tested with .net 4.0 The question is why VS catches but runtime do not?

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  • Can you get a Func<T> (or similar) from a MethodInfo object?

    - by Dan Tao
    I realize that, generally speaking, there are performance implications of using reflection. (I myself am not a fan of reflection at all, actually; this is a purely academic question.) Suppose there exists some class that looks like this: public class MyClass { public string GetName() { return "My Name"; } } Bear with me here. I know that if I have an instance of MyClass called x, I can call x.GetName(). Furthermore, I could set a Func<string> variable to x.GetName. Now here's my question. Let's say I don't know the above class is called MyClass; I've got some object, x, but I have no idea what it is. I could check to see if that object has a GetName method by doing this: MethodInfo getName = x.GetType().GetMethod("GetName"); Suppose getName is not null. Then couldn't I furthermore check if getName.ReturnType == typeof(string) and getName.GetParameters().Length == 0, and at this point, wouldn't I be quite certain that the method represented by my getName object could definitely be cast to a Func<string>, somehow? I realize there's a MethodInfo.Invoke, and I also realize I could always create a Func<string> like: Func<string> getNameFunc = () => getName.Invoke(x, null); I guess what I'm asking is if there's any way to go from a MethodInfo object to the actual method it represents, incurring the performance cost of reflection in the process, but after that point being able to call the method directly (via, e.g., a Func<string> or something similar) without a performance penalty. What I'm envisioning might look something like this: // obviously this would throw an exception if GetActualInstanceMethod returned // something that couldn't be cast to a Func<string> Func<string> getNameFunc = (Func<string>)getName.GetActualInstanceMethod(x); (I realize that doesn't exist; I'm wondering if there's anything like it.) If what I'm asking doesn't make sense, or if I'm being unclear, I'll be happy to attempt to clarify.

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  • Pluggable Rules for Entity Framework Code First

    - by Ricardo Peres
    Suppose you want a system that lets you plug custom validation rules on your Entity Framework context. The rules would control whether an entity can be saved, updated or deleted, and would be implemented in plain .NET. Yes, I know I already talked about plugable validation in Entity Framework Code First, but this is a different approach. An example API is in order, first, a ruleset, which will hold the collection of rules: 1: public interface IRuleset : IDisposable 2: { 3: void AddRule<T>(IRule<T> rule); 4: IEnumerable<IRule<T>> GetRules<T>(); 5: } Next, a rule: 1: public interface IRule<T> 2: { 3: Boolean CanSave(T entity, DbContext ctx); 4: Boolean CanUpdate(T entity, DbContext ctx); 5: Boolean CanDelete(T entity, DbContext ctx); 6: String Name 7: { 8: get; 9: } 10: } Let’s analyze what we have, starting with the ruleset: Only has methods for adding a rule, specific to an entity type, and to list all rules of this entity type; By implementing IDisposable, we allow it to be cancelled, by disposing of it when we no longer want its rules to be applied. A rule, on the other hand: Has discrete methods for checking if a given entity can be saved, updated or deleted, which receive as parameters the entity itself and a pointer to the DbContext to which the ruleset was applied; Has a name property for helping us identifying what failed. A ruleset really doesn’t need a public implementation, all we need is its interface. The private (internal) implementation might look like this: 1: sealed class Ruleset : IRuleset 2: { 3: private readonly IDictionary<Type, HashSet<Object>> rules = new Dictionary<Type, HashSet<Object>>(); 4: private ObjectContext octx = null; 5:  6: internal Ruleset(ObjectContext octx) 7: { 8: this.octx = octx; 9: } 10:  11: public void AddRule<T>(IRule<T> rule) 12: { 13: if (this.rules.ContainsKey(typeof(T)) == false) 14: { 15: this.rules[typeof(T)] = new HashSet<Object>(); 16: } 17:  18: this.rules[typeof(T)].Add(rule); 19: } 20:  21: public IEnumerable<IRule<T>> GetRules<T>() 22: { 23: if (this.rules.ContainsKey(typeof(T)) == true) 24: { 25: foreach (IRule<T> rule in this.rules[typeof(T)]) 26: { 27: yield return (rule); 28: } 29: } 30: } 31:  32: public void Dispose() 33: { 34: this.octx.SavingChanges -= RulesExtensions.OnSaving; 35: RulesExtensions.rulesets.Remove(this.octx); 36: this.octx = null; 37:  38: this.rules.Clear(); 39: } 40: } Basically, this implementation: Stores the ObjectContext of the DbContext to which it was created for, this is so that later we can remove the association; Has a collection - a set, actually, which does not allow duplication - of rules indexed by the real Type of an entity (because of proxying, an entity may be of a type that inherits from the class that we declared); Has generic methods for adding and enumerating rules of a given type; Has a Dispose method for cancelling the enforcement of the rules. A (really dumb) rule applied to Product might look like this: 1: class ProductRule : IRule<Product> 2: { 3: #region IRule<Product> Members 4:  5: public String Name 6: { 7: get 8: { 9: return ("Rule 1"); 10: } 11: } 12:  13: public Boolean CanSave(Product entity, DbContext ctx) 14: { 15: return (entity.Price > 10000); 16: } 17:  18: public Boolean CanUpdate(Product entity, DbContext ctx) 19: { 20: return (true); 21: } 22:  23: public Boolean CanDelete(Product entity, DbContext ctx) 24: { 25: return (true); 26: } 27:  28: #endregion 29: } The DbContext is there because we may need to check something else in the database before deciding whether to allow an operation or not. And here’s how to apply this mechanism to any DbContext, without requiring the usage of a subclass, by means of an extension method: 1: public static class RulesExtensions 2: { 3: private static readonly MethodInfo getRulesMethod = typeof(IRuleset).GetMethod("GetRules"); 4: internal static readonly IDictionary<ObjectContext, Tuple<IRuleset, DbContext>> rulesets = new Dictionary<ObjectContext, Tuple<IRuleset, DbContext>>(); 5:  6: private static Type GetRealType(Object entity) 7: { 8: return (entity.GetType().Assembly.IsDynamic == true ? entity.GetType().BaseType : entity.GetType()); 9: } 10:  11: internal static void OnSaving(Object sender, EventArgs e) 12: { 13: ObjectContext octx = sender as ObjectContext; 14: IRuleset ruleset = rulesets[octx].Item1; 15: DbContext ctx = rulesets[octx].Item2; 16:  17: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Added)) 18: { 19: Object entity = entry.Entity; 20: Type realType = GetRealType(entity); 21:  22: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 23: { 24: if (rule.CanSave(entity, ctx) == false) 25: { 26: throw (new Exception(String.Format("Cannot save entity {0} due to rule {1}", entity, rule.Name))); 27: } 28: } 29: } 30:  31: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Deleted)) 32: { 33: Object entity = entry.Entity; 34: Type realType = GetRealType(entity); 35:  36: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 37: { 38: if (rule.CanDelete(entity, ctx) == false) 39: { 40: throw (new Exception(String.Format("Cannot delete entity {0} due to rule {1}", entity, rule.Name))); 41: } 42: } 43: } 44:  45: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Modified)) 46: { 47: Object entity = entry.Entity; 48: Type realType = GetRealType(entity); 49:  50: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 51: { 52: if (rule.CanUpdate(entity, ctx) == false) 53: { 54: throw (new Exception(String.Format("Cannot update entity {0} due to rule {1}", entity, rule.Name))); 55: } 56: } 57: } 58: } 59:  60: public static IRuleset CreateRuleset(this DbContext context) 61: { 62: Tuple<IRuleset, DbContext> ruleset = null; 63: ObjectContext octx = (context as IObjectContextAdapter).ObjectContext; 64:  65: if (rulesets.TryGetValue(octx, out ruleset) == false) 66: { 67: ruleset = rulesets[octx] = new Tuple<IRuleset, DbContext>(new Ruleset(octx), context); 68: 69: octx.SavingChanges += OnSaving; 70: } 71:  72: return (ruleset.Item1); 73: } 74: } It relies on the SavingChanges event of the ObjectContext to intercept the saving operations before they are actually issued. Yes, it uses a bit of dynamic magic! Very handy, by the way! So, let’s put it all together: 1: using (MyContext ctx = new MyContext()) 2: { 3: IRuleset rules = ctx.CreateRuleset(); 4: rules.AddRule(new ProductRule()); 5:  6: ctx.Products.Add(new Product() { Name = "xyz", Price = 50000 }); 7:  8: ctx.SaveChanges(); //an exception is fired here 9:  10: //when we no longer need to apply the rules 11: rules.Dispose(); 12: } Feel free to use it and extend it any way you like, and do give me your feedback! As a final note, this can be easily changed to support plain old Entity Framework (not Code First, that is), if that is what you are using.

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  • How do I make solr/jetty find the installed slf4j jars in Ubuntu 12.04?

    - by J. Pablo Fernández
    I'm running Ubuntu 12.04's packaged Jetty in which I installed solr 4.3.1 (by copying the war file to /var/lib/jetty/webapps. When I start Jetty, I get this error: failed SolrRequestFilter: org.apache.solr.common.SolrException: Could not find necessary SLF4j logging jars. If using Jetty, the SLF4j logging jars need to go in the jetty lib/ext directory. The package libslf4j-java is installed, and the jars are in /usr/share/java: /usr/share/java/log4j-over-slf4j.jar /usr/share/java/slf4j-api.jar /usr/share/java/slf4j-jcl.jar /usr/share/java/slf4j-jdk14.jar /usr/share/java/slf4j-log4j12.jar /usr/share/java/slf4j-migrator.jar /usr/share/java/slf4j-nop.jar /usr/share/java/slf4j-simple.jar but somehow, Jetty and/or Solr are not finding them. How do I make them find them? or how do I install some other jars where jetty/solr would find them? The full error is: 88 [main] INFO org.mortbay.log - jetty-6.1.24 443 [main] INFO org.mortbay.log - Deploy /etc/jetty/contexts/javadoc.xml -> org.mortbay.jetty.handler.ContextHandler@cec0c5{/javadoc,file:/usr/share/jetty/javadoc} 522 [main] INFO org.mortbay.log - Extract file:/var/lib/jetty/webapps/solr.war to /var/cache/jetty/data/Jetty__8080_solr.war__solr__zdafkg/webapp 1501 [main] WARN org.mortbay.log - failed SolrRequestFilter: org.apache.solr.common.SolrException: Could not find necessary SLF4j logging jars. If using Jetty, the SLF4j logging jars need to go in the jetty lib/ext directory. For other containers, the corresponding directory should be used. For more information, see: http://wiki.apache.org/solr/SolrLogging 1501 [main] ERROR org.mortbay.log - Failed startup of context org.mortbay.jetty.webapp.WebAppContext@5329c5{/solr,file:/var/lib/jetty/webapps/solr.war} org.apache.solr.common.SolrException: Could not find necessary SLF4j logging jars. If using Jetty, the SLF4j logging jars need to go in the jetty lib/ext directory. For other containers, the corresponding directory should be used. For more information, see: http://wiki.apache.org/solr/SolrLogging at org.apache.solr.servlet.SolrDispatchFilter.<init>(SolrDispatchFilter.java:105) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:532) at java.lang.Class.newInstance0(Class.java:374) at java.lang.Class.newInstance(Class.java:327) at org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:153) at org.mortbay.jetty.servlet.FilterHolder.doStart(FilterHolder.java:92) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:662) at org.mortbay.jetty.servlet.Context.startContext(Context.java:140) at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250) at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:518) at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152) at org.mortbay.jetty.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:156) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130) at org.mortbay.jetty.Server.doStart(Server.java:224) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.xml.XmlConfiguration.main(XmlConfiguration.java:985) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.mortbay.start.Main.invokeMain(Main.java:194) at org.mortbay.start.Main.start(Main.java:534) at org.mortbay.jetty.start.daemon.Bootstrap.start(Bootstrap.java:30) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:243) Caused by: java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory at org.apache.solr.servlet.SolrDispatchFilter.<init>(SolrDispatchFilter.java:103) ... 36 more Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:392) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:363) ... 37 more 1505 [main] WARN org.mortbay.log - failed org.mortbay.jetty.webapp.WebAppContext@5329c5{/solr,file:/var/lib/jetty/webapps/solr.war}: java.lang.NoClassDefFoundError: org/slf4j/Logger 1579 [main] WARN org.mortbay.log - failed ContextHandlerCollection@19d0a1: java.lang.NoClassDefFoundError: org/slf4j/Logger 1582 [main] INFO org.mortbay.log - Opened /var/log/jetty/2013_06_27.request.log 1582 [main] WARN org.mortbay.log - failed HandlerCollection@cbf30e: java.lang.NoClassDefFoundError: org/slf4j/Logger 1582 [main] ERROR org.mortbay.log - Error starting handlers java.lang.NoClassDefFoundError: org/slf4j/Logger at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2454) at java.lang.Class.getMethod0(Class.java:2697) at java.lang.Class.getMethod(Class.java:1622) at org.mortbay.log.Log.unwind(Log.java:228) at org.mortbay.log.Log.warn(Log.java:197) at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:475) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152) at org.mortbay.jetty.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:156) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130) at org.mortbay.jetty.Server.doStart(Server.java:224) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.xml.XmlConfiguration.main(XmlConfiguration.java:985) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.mortbay.start.Main.invokeMain(Main.java:194) at org.mortbay.start.Main.start(Main.java:534) at org.mortbay.jetty.start.daemon.Bootstrap.start(Bootstrap.java:30) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:243) Caused by: java.lang.ClassNotFoundException: org.slf4j.Logger at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:392) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:363) ... 29 more

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  • Creating a dynamic proxy generator with c# – Part 4 – Calling the base method

    - by SeanMcAlinden
    Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors   The plan for calling the base methods from the proxy is to create a private method for each overridden proxy method, this will allow the proxy to use a delegate to simply invoke the private method when required. Quite a few helper classes have been created to make this possible so as usual I would suggest download or viewing the code at http://rapidioc.codeplex.com/. In this post I’m just going to cover the main points for when creating methods. Getting the methods to override The first two notable methods are for getting the methods. private static MethodInfo[] GetMethodsToOverride<TBase>() where TBase : class {     return typeof(TBase).GetMethods().Where(x =>         !methodsToIgnore.Contains(x.Name) &&                              (x.Attributes & MethodAttributes.Final) == 0)         .ToArray(); } private static StringCollection GetMethodsToIgnore() {     return new StringCollection()     {         "ToString",         "GetHashCode",         "Equals",         "GetType"     }; } The GetMethodsToIgnore method string collection contains an array of methods that I don’t want to override. In the GetMethodsToOverride method, you’ll notice a binary AND which is basically saying not to include any methods marked final i.e. not virtual. Creating the MethodInfo for calling the base method This method should hopefully be fairly easy to follow, it’s only function is to create a MethodInfo which points to the correct base method, and with the correct parameters. private static MethodInfo CreateCallBaseMethodInfo<TBase>(MethodInfo method) where TBase : class {     Type[] baseMethodParameterTypes = ParameterHelper.GetParameterTypes(method, method.GetParameters());       return typeof(TBase).GetMethod(        method.Name,        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        baseMethodParameterTypes,        null     ); }   /// <summary> /// Get the parameter types. /// </summary> /// <param name="method">The method.</param> /// <param name="parameters">The parameters.</param> public static Type[] GetParameterTypes(MethodInfo method, ParameterInfo[] parameters) {     Type[] parameterTypesList = Type.EmptyTypes;       if (parameters.Length > 0)     {         parameterTypesList = CreateParametersList(parameters);     }     return parameterTypesList; }   Creating the new private methods for calling the base method The following method outline how I’ve created the private methods for calling the base class method. private static MethodBuilder CreateCallBaseMethodBuilder(TypeBuilder typeBuilder, MethodInfo method) {     string callBaseSuffix = "GetBaseMethod";       if (method.IsGenericMethod || method.IsGenericMethodDefinition)     {                         return MethodHelper.SetUpGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     }     else     {         return MethodHelper.SetupNonGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     } } The CreateCallBaseMethodBuilder is the entry point method for creating the call base method. I’ve added a suffix to the base classes method name to keep it unique. Non Generic Methods Creating a non generic method is fairly simple public static MethodBuilder SetupNonGenericMethod(     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       Type returnType = method.ReturnType;       MethodBuilder methodBuilder = CreateMethodBuilder         (             typeBuilder,             method,             methodName,             methodAttributes,             parameterTypes,             returnType         );       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static MethodBuilder CreateMethodBuilder (     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes,     Type[] parameterTypes,     Type returnType ) { MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, methodAttributes, returnType, parameterTypes); return methodBuilder; } As you can see, you simply have to declare a method builder, get the parameter types, and set the method attributes you want.   Generic Methods Creating generic methods takes a little bit more work. /// <summary> /// Sets up generic method. /// </summary> /// <param name="typeBuilder">The type builder.</param> /// <param name="method">The method.</param> /// <param name="methodName">Name of the method.</param> /// <param name="methodAttributes">The method attributes.</param> public static MethodBuilder SetUpGenericMethod     (         TypeBuilder typeBuilder,         MethodInfo method,         string methodName,         MethodAttributes methodAttributes     ) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName,         methodAttributes);       Type[] genericArguments = method.GetGenericArguments();       GenericTypeParameterBuilder[] genericTypeParameters =         GetGenericTypeParameters(methodBuilder, genericArguments);       ParameterHelper.SetUpParameterConstraints(parameterTypes, genericTypeParameters);       SetUpReturnType(method, methodBuilder, genericTypeParameters);       if (method.IsGenericMethod)     {         methodBuilder.MakeGenericMethod(genericArguments);     }       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static GenericTypeParameterBuilder[] GetGenericTypeParameters     (         MethodBuilder methodBuilder,         Type[] genericArguments     ) {     return methodBuilder.DefineGenericParameters(GenericsHelper.GetArgumentNames(genericArguments)); }   private static void SetUpReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.IsGenericMethodDefinition)     {         SetUpGenericDefinitionReturnType(method, methodBuilder, genericTypeParameters);     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     } }   private static void SetUpGenericDefinitionReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.ReturnType == null)     {         methodBuilder.SetReturnType(typeof(void));     }     else if (method.ReturnType.IsGenericType)     {         methodBuilder.SetReturnType(genericTypeParameters.Where             (x => x.Name == method.ReturnType.Name).First());     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     }             } Ok, there are a few helper methods missing, basically there is way to much code to put in this post, take a look at the code at http://rapidioc.codeplex.com/ to follow it through completely. Basically though, when dealing with generics there is extra work to do in terms of getting the generic argument types setting up any generic parameter constraints setting up the return type setting up the method as a generic All of the information is easy to get via reflection from the MethodInfo.   Emitting the new private method Emitting the new private method is relatively simple as it’s only function is calling the base method and returning a result if the return type is not void. ILGenerator il = privateMethodBuilder.GetILGenerator();   EmitCallBaseMethod(method, callBaseMethod, il);   private static void EmitCallBaseMethod(MethodInfo method, MethodInfo callBaseMethod, ILGenerator il) {     int privateParameterCount = method.GetParameters().Length;       il.Emit(OpCodes.Ldarg_0);       if (privateParameterCount > 0)     {         for (int arg = 0; arg < privateParameterCount; arg++)         {             il.Emit(OpCodes.Ldarg_S, arg + 1);         }     }       il.Emit(OpCodes.Call, callBaseMethod);       il.Emit(OpCodes.Ret); } So in the main method building method, an ILGenerator is created from the method builder. The ILGenerator performs the following actions: Load the class (this) onto the stack using the hidden argument Ldarg_0. Create an argument on the stack for each of the method parameters (starting at 1 because 0 is the hidden argument) Call the base method using the Opcodes.Call code and the MethodInfo we created earlier. Call return on the method   Conclusion Now we have the private methods prepared for calling the base method, we have reached the last of the relatively easy part of the proxy building. Hopefully, it hasn’t been too hard to follow so far, there is a lot of code so I haven’t been able to post it all so please check it out at http://rapidioc.codeplex.com/. The next section should be up fairly soon, it’s going to cover creating the delegates for calling the private methods created in this post.   Kind Regards, Sean.

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  • ASP.NET MVC Validation Complete

    - by Ricardo Peres
    OK, so let’s talk about validation. Most people are probably familiar with the out of the box validation attributes that MVC knows about, from the System.ComponentModel.DataAnnotations namespace, such as EnumDataTypeAttribute, RequiredAttribute, StringLengthAttribute, RangeAttribute, RegularExpressionAttribute and CompareAttribute from the System.Web.Mvc namespace. All of these validators inherit from ValidationAttribute and perform server as well as client-side validation. In order to use them, you must include the JavaScript files MicrosoftMvcValidation.js, jquery.validate.js or jquery.validate.unobtrusive.js, depending on whether you want to use Microsoft’s own library or jQuery. No significant difference exists, but jQuery is more extensible. You can also create your own attribute by inheriting from ValidationAttribute, but, if you want to have client-side behavior, you must also implement IClientValidatable (all of the out of the box validation attributes implement it) and supply your own JavaScript validation function that mimics its server-side counterpart. Of course, you must reference the JavaScript file where the declaration function is. Let’s see an example, validating even numbers. First, the validation attribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public class IsEvenAttribute : ValidationAttribute, IClientValidatable 4: { 5: protected override ValidationResult IsValid(Object value, ValidationContext validationContext) 6: { 7: Int32 v = Convert.ToInt32(value); 8:  9: if (v % 2 == 0) 10: { 11: return (ValidationResult.Success); 12: } 13: else 14: { 15: return (new ValidationResult("Value is not even")); 16: } 17: } 18:  19: #region IClientValidatable Members 20:  21: public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) 22: { 23: yield return (new ModelClientValidationRule() { ValidationType = "iseven", ErrorMessage = "Value is not even" }); 24: } 25:  26: #endregion 27: } The iseven validation function is declared like this in JavaScript, using jQuery validation: 1: jQuery.validator.addMethod('iseven', function (value, element, params) 2: { 3: return (true); 4: return ((parseInt(value) % 2) == 0); 5: }); 6:  7: jQuery.validator.unobtrusive.adapters.add('iseven', [], function (options) 8: { 9: options.rules['iseven'] = options.params; 10: options.messages['iseven'] = options.message; 11: }); Do keep in mind that this is a simple example, for example, we are not using parameters, which may be required for some more advanced scenarios. As a side note, if you implement a custom validator that also requires a JavaScript function, you’ll probably want them together. One way to achieve this is by including the JavaScript file as an embedded resource on the same assembly where the custom attribute is declared. You do this by having its Build Action set as Embedded Resource inside Visual Studio: Then you have to declare an attribute at assembly level, perhaps in the AssemblyInfo.cs file: 1: [assembly: WebResource("SomeNamespace.IsEven.js", "text/javascript")] In your views, if you want to include a JavaScript file from an embedded resource you can use this code: 1: public static class UrlExtensions 2: { 3: private static readonly MethodInfo getResourceUrlMethod = typeof(AssemblyResourceLoader).GetMethod("GetWebResourceUrlInternal", BindingFlags.NonPublic | BindingFlags.Static); 4:  5: public static IHtmlString Resource<TType>(this UrlHelper url, String resourceName) 6: { 7: return (Resource(url, typeof(TType).Assembly.FullName, resourceName)); 8: } 9:  10: public static IHtmlString Resource(this UrlHelper url, String assemblyName, String resourceName) 11: { 12: String resourceUrl = getResourceUrlMethod.Invoke(null, new Object[] { Assembly.Load(assemblyName), resourceName, false, false, null }).ToString(); 13: return (new HtmlString(resourceUrl)); 14: } 15: } And on the view: 1: <script src="<%: this.Url.Resource("SomeAssembly", "SomeNamespace.IsEven.js") %>" type="text/javascript"></script> Then there’s the CustomValidationAttribute. It allows externalizing your validation logic to another class, so you have to tell which type and method to use. The method can be static as well as instance, if it is instance, the class cannot be abstract and must have a public parameterless constructor. It can be applied to a property as well as a class. It does not, however, support client-side validation. Let’s see an example declaration: 1: [CustomValidation(typeof(ProductValidator), "OnValidateName")] 2: public String Name 3: { 4: get; 5: set; 6: } The validation method needs this signature: 1: public static ValidationResult OnValidateName(String name) 2: { 3: if ((String.IsNullOrWhiteSpace(name) == false) && (name.Length <= 50)) 4: { 5: return (ValidationResult.Success); 6: } 7: else 8: { 9: return (new ValidationResult(String.Format("The name has an invalid value: {0}", name), new String[] { "Name" })); 10: } 11: } Note that it can be either static or instance and it must return a ValidationResult-derived class. ValidationResult.Success is null, so any non-null value is considered a validation error. The single method argument must match the property type to which the attribute is attached to or the class, in case it is applied to a class: 1: [CustomValidation(typeof(ProductValidator), "OnValidateProduct")] 2: public class Product 3: { 4: } The signature must thus be: 1: public static ValidationResult OnValidateProduct(Product product) 2: { 3: } Continuing with attribute-based validation, another possibility is RemoteAttribute. This allows specifying a controller and an action method just for performing the validation of a property or set of properties. This works in a client-side AJAX way and it can be very useful. Let’s see an example, starting with the attribute declaration and proceeding to the action method implementation: 1: [Remote("Validate", "Validation")] 2: public String Username 3: { 4: get; 5: set; 6: } The controller action method must contain an argument that can be bound to the property: 1: public ActionResult Validate(String username) 2: { 3: return (this.Json(true, JsonRequestBehavior.AllowGet)); 4: } If in your result JSON object you include a string instead of the true value, it will consider it as an error, and the validation will fail. This string will be displayed as the error message, if you have included it in your view. You can also use the remote validation approach for validating your entire entity, by including all of its properties as included fields in the attribute and having an action method that receives an entity instead of a single property: 1: [Remote("Validate", "Validation", AdditionalFields = "Price")] 2: public String Name 3: { 4: get; 5: set; 6: } 7:  8: public Decimal Price 9: { 10: get; 11: set; 12: } The action method will then be: 1: public ActionResult Validate(Product product) 2: { 3: return (this.Json("Product is not valid", JsonRequestBehavior.AllowGet)); 4: } Only the property to which the attribute is applied and the additional properties referenced by the AdditionalFields will be populated in the entity instance received by the validation method. The same rule previously stated applies, if you return anything other than true, it will be used as the validation error message for the entity. The remote validation is triggered automatically, but you can also call it explicitly. In the next example, I am causing the full entity validation, see the call to serialize(): 1: function validate() 2: { 3: var form = $('form'); 4: var data = form.serialize(); 5: var url = '<%: this.Url.Action("Validation", "Validate") %>'; 6:  7: var result = $.ajax 8: ( 9: { 10: type: 'POST', 11: url: url, 12: data: data, 13: async: false 14: } 15: ).responseText; 16:  17: if (result) 18: { 19: //error 20: } 21: } Finally, by implementing IValidatableObject, you can implement your validation logic on the object itself, that is, you make it self-validatable. This will only work server-side, that is, the ModelState.IsValid property will be set to false on the controller’s action method if the validation in unsuccessful. Let’s see how to implement it: 1: public class Product : IValidatableObject 2: { 3: public String Name 4: { 5: get; 6: set; 7: } 8:  9: public Decimal Price 10: { 11: get; 12: set; 13: } 14:  15: #region IValidatableObject Members 16: 17: public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 18: { 19: if ((String.IsNullOrWhiteSpace(this.Name) == true) || (this.Name.Length > 50)) 20: { 21: yield return (new ValidationResult(String.Format("The name has an invalid value: {0}", this.Name), new String[] { "Name" })); 22: } 23: 24: if ((this.Price <= 0) || (this.Price > 100)) 25: { 26: yield return (new ValidationResult(String.Format("The price has an invalid value: {0}", this.Price), new String[] { "Price" })); 27: } 28: } 29: 30: #endregion 31: } The errors returned will be matched against the model properties through the MemberNames property of the ValidationResult class and will be displayed in their proper labels, if present on the view. On the controller action method you can check for model validity by looking at ModelState.IsValid and you can get actual error messages and related properties by examining all of the entries in the ModelState dictionary: 1: Dictionary<String, String> errors = new Dictionary<String, String>(); 2:  3: foreach (KeyValuePair<String, ModelState> keyValue in this.ModelState) 4: { 5: String key = keyValue.Key; 6: ModelState modelState = keyValue.Value; 7:  8: foreach (ModelError error in modelState.Errors) 9: { 10: errors[key] = error.ErrorMessage; 11: } 12: } And these are the ways to perform date validation in ASP.NET MVC. Don’t forget to use them!

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  • Unity – Part 5: Injecting Values

    - by Ricardo Peres
    Introduction This is the fifth post on Unity. You can find the introductory post here, the second post, on dependency injection here, a third one on Aspect Oriented Programming (AOP) here and the latest so far, on writing custom extensions, here. This time we will talk about injecting simple values. An Inversion of Control (IoC) / Dependency Injector (DI) container like Unity can be used for things other than injecting complex class dependencies. It can also be used for setting property values or method/constructor parameters whenever a class is built. The main difference is that these values do not have a lifetime manager associated with them and do not come from the regular IoC registration store. Unlike, for instance, MEF, Unity won’t let you register as a dependency a string or an integer, so you have to take a different approach, which I will describe in this post. Scenario Let’s imagine we have a base interface that describes a logger – the same as in previous examples: 1: public interface ILogger 2: { 3: void Log(String message); 4: } And a concrete implementation that writes to a file: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8:  9: #region ILogger Members 10:  11: public void Log(String message) 12: { 13: using (Stream file = File.OpenWrite(this.Filename)) 14: { 15: Byte[] data = Encoding.Default.GetBytes(message); 16: 17: file.Write(data, 0, data.Length); 18: } 19: } 20:  21: #endregion 22: } And let’s say we want the Filename property to come from the application settings (appSettings) section on the Web/App.config file. As usual with Unity, there is an extensibility point that allows us to automatically do this, both with code configuration or statically on the configuration file. Extending Injection We start by implementing a class that will retrieve a value from the appSettings by inheriting from ValueElement: 1: sealed class AppSettingsParameterValueElement : ValueElement, IDependencyResolverPolicy 2: { 3: #region Private methods 4: private Object CreateInstance(Type parameterType) 5: { 6: Object configurationValue = ConfigurationManager.AppSettings[this.AppSettingsKey]; 7:  8: if (parameterType != typeof(String)) 9: { 10: TypeConverter typeConverter = this.GetTypeConverter(parameterType); 11:  12: configurationValue = typeConverter.ConvertFromInvariantString(configurationValue as String); 13: } 14:  15: return (configurationValue); 16: } 17: #endregion 18:  19: #region Private methods 20: private TypeConverter GetTypeConverter(Type parameterType) 21: { 22: if (String.IsNullOrEmpty(this.TypeConverterTypeName) == false) 23: { 24: return (Activator.CreateInstance(TypeResolver.ResolveType(this.TypeConverterTypeName)) as TypeConverter); 25: } 26: else 27: { 28: return (TypeDescriptor.GetConverter(parameterType)); 29: } 30: } 31: #endregion 32:  33: #region Public override methods 34: public override InjectionParameterValue GetInjectionParameterValue(IUnityContainer container, Type parameterType) 35: { 36: Object value = this.CreateInstance(parameterType); 37: return (new InjectionParameter(parameterType, value)); 38: } 39: #endregion 40:  41: #region IDependencyResolverPolicy Members 42:  43: public Object Resolve(IBuilderContext context) 44: { 45: Type parameterType = null; 46:  47: if (context.CurrentOperation is ResolvingPropertyValueOperation) 48: { 49: ResolvingPropertyValueOperation op = (context.CurrentOperation as ResolvingPropertyValueOperation); 50: PropertyInfo prop = op.TypeBeingConstructed.GetProperty(op.PropertyName); 51: parameterType = prop.PropertyType; 52: } 53: else if (context.CurrentOperation is ConstructorArgumentResolveOperation) 54: { 55: ConstructorArgumentResolveOperation op = (context.CurrentOperation as ConstructorArgumentResolveOperation); 56: String args = op.ConstructorSignature.Split('(')[1].Split(')')[0]; 57: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 58: ConstructorInfo ctor = op.TypeBeingConstructed.GetConstructor(types); 59: parameterType = ctor.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 60: } 61: else if (context.CurrentOperation is MethodArgumentResolveOperation) 62: { 63: MethodArgumentResolveOperation op = (context.CurrentOperation as MethodArgumentResolveOperation); 64: String methodName = op.MethodSignature.Split('(')[0].Split(' ')[1]; 65: String args = op.MethodSignature.Split('(')[1].Split(')')[0]; 66: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 67: MethodInfo method = op.TypeBeingConstructed.GetMethod(methodName, types); 68: parameterType = method.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 69: } 70:  71: return (this.CreateInstance(parameterType)); 72: } 73:  74: #endregion 75:  76: #region Public properties 77: [ConfigurationProperty("appSettingsKey", IsRequired = true)] 78: public String AppSettingsKey 79: { 80: get 81: { 82: return ((String)base["appSettingsKey"]); 83: } 84:  85: set 86: { 87: base["appSettingsKey"] = value; 88: } 89: } 90: #endregion 91: } As you can see from the implementation of the IDependencyResolverPolicy.Resolve method, this will work in three different scenarios: When it is applied to a property; When it is applied to a constructor parameter; When it is applied to an initialization method. The implementation will even try to convert the value to its declared destination, for example, if the destination property is an Int32, it will try to convert the appSettings stored string to an Int32. Injection By Configuration If we want to configure injection by configuration, we need to implement a custom section extension by inheriting from SectionExtension, and registering our custom element with the name “appSettings”: 1: sealed class AppSettingsParameterInjectionElementExtension : SectionExtension 2: { 3: public override void AddExtensions(SectionExtensionContext context) 4: { 5: context.AddElement<AppSettingsParameterValueElement>("appSettings"); 6: } 7: } And on the configuration file, for setting a property, we use it like this: 1: <appSettings> 2: <add key="LoggerFilename" value="Log.txt"/> 3: </appSettings> 4: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 5: <container> 6: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 7: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 8: <lifetime type="singleton"/> 9: <property name="Filename"> 10: <appSettings appSettingsKey="LoggerFilename"/> 11: </property> 12: </register> 13: </container> 14: </unity> If we would like to inject the value as a constructor parameter, it would be instead: 1: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 2: <sectionExtension type="MyNamespace.AppSettingsParameterInjectionElementExtension, MyAssembly" /> 3: <container> 4: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 5: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 6: <lifetime type="singleton"/> 7: <constructor> 8: <param name="filename" type="System.String"> 9: <appSettings appSettingsKey="LoggerFilename"/> 10: </param> 11: </constructor> 12: </register> 13: </container> 14: </unity> Notice the appSettings section, where we add a LoggerFilename entry, which is the same as the one referred by our AppSettingsParameterInjectionElementExtension extension. For more advanced behavior, you can add a TypeConverterName attribute to the appSettings declaration, where you can pass an assembly qualified name of a class that inherits from TypeConverter. This class will be responsible for converting the appSettings value to a destination type. Injection By Attribute If we would like to use attributes instead, we need to create a custom attribute by inheriting from DependencyResolutionAttribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public sealed class AppSettingsDependencyResolutionAttribute : DependencyResolutionAttribute 4: { 5: public AppSettingsDependencyResolutionAttribute(String appSettingsKey) 6: { 7: this.AppSettingsKey = appSettingsKey; 8: } 9:  10: public String TypeConverterTypeName 11: { 12: get; 13: set; 14: } 15:  16: public String AppSettingsKey 17: { 18: get; 19: private set; 20: } 21:  22: public override IDependencyResolverPolicy CreateResolver(Type typeToResolve) 23: { 24: return (new AppSettingsParameterValueElement() { AppSettingsKey = this.AppSettingsKey, TypeConverterTypeName = this.TypeConverterTypeName }); 25: } 26: } As for file configuration, there is a mandatory property for setting the appSettings key and an optional TypeConverterName  for setting the name of a TypeConverter. Both the custom attribute and the custom section return an instance of the injector AppSettingsParameterValueElement that we implemented in the first place. Now, the attribute needs to be placed before the injected class’ Filename property: 1: public class FileLogger : ILogger 2: { 3: [AppSettingsDependencyResolution("LoggerFilename")] 4: public String Filename 5: { 6: get; 7: set; 8: } 9:  10: #region ILogger Members 11:  12: public void Log(String message) 13: { 14: using (Stream file = File.OpenWrite(this.Filename)) 15: { 16: Byte[] data = Encoding.Default.GetBytes(message); 17: 18: file.Write(data, 0, data.Length); 19: } 20: } 21:  22: #endregion 23: } Or, if we wanted to use constructor injection: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8:  9: public FileLogger([AppSettingsDependencyResolution("LoggerFilename")] String filename) 10: { 11: this.Filename = filename; 12: } 13:  14: #region ILogger Members 15:  16: public void Log(String message) 17: { 18: using (Stream file = File.OpenWrite(this.Filename)) 19: { 20: Byte[] data = Encoding.Default.GetBytes(message); 21: 22: file.Write(data, 0, data.Length); 23: } 24: } 25:  26: #endregion 27: } Usage Just do: 1: ILogger logger = ServiceLocator.Current.GetInstance<ILogger>("File"); And off you go! A simple way do avoid hardcoded values in component registrations. Of course, this same concept can be applied to registry keys, environment values, XML attributes, etc, etc, just change the implementation of the AppSettingsParameterValueElement class. Next stop: custom lifetime managers.

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  • Call Webservice without adding a WebReference - with Complex Types

    - by ck
    I'm using the code at This Site to call a webservice dynamically. [SecurityPermissionAttribute(SecurityAction.Demand, Unrestricted = true)] public static object CallWebService(string webServiceAsmxUrl, string serviceName, string methodName, object[] args) { System.Net.WebClient client = new System.Net.WebClient(); //-Connect To the web service using (System.IO.Stream stream = client.OpenRead(webServiceAsmxUrl + "?wsdl")) { //--Now read the WSDL file describing a service. ServiceDescription description = ServiceDescription.Read(stream); ///// LOAD THE DOM ///////// //--Initialize a service description importer. ServiceDescriptionImporter importer = new ServiceDescriptionImporter(); importer.ProtocolName = "Soap12"; // Use SOAP 1.2. importer.AddServiceDescription(description, null, null); //--Generate a proxy client. importer.Style = ServiceDescriptionImportStyle.Client; //--Generate properties to represent primitive values. importer.CodeGenerationOptions = System.Xml.Serialization.CodeGenerationOptions.GenerateProperties; //--Initialize a Code-DOM tree into which we will import the service. CodeNamespace nmspace = new CodeNamespace(); CodeCompileUnit unit1 = new CodeCompileUnit(); unit1.Namespaces.Add(nmspace); //--Import the service into the Code-DOM tree. This creates proxy code //--that uses the service. ServiceDescriptionImportWarnings warning = importer.Import(nmspace, unit1); if (warning == 0) //--If zero then we are good to go { //--Generate the proxy code CodeDomProvider provider1 = CodeDomProvider.CreateProvider("CSharp"); //--Compile the assembly proxy with the appropriate references string[] assemblyReferences = new string[5] { "System.dll", "System.Web.Services.dll", "System.Web.dll", "System.Xml.dll", "System.Data.dll" }; CompilerParameters parms = new CompilerParameters(assemblyReferences); CompilerResults results = provider1.CompileAssemblyFromDom(parms, unit1); //-Check For Errors if (results.Errors.Count > 0) { StringBuilder sb = new StringBuilder(); foreach (CompilerError oops in results.Errors) { sb.AppendLine("========Compiler error============"); sb.AppendLine(oops.ErrorText); } throw new System.ApplicationException("Compile Error Occured calling webservice. " + sb.ToString()); } //--Finally, Invoke the web service method Type foundType = null; Type[] types = results.CompiledAssembly.GetTypes(); foreach (Type type in types) { if (type.BaseType == typeof(System.Web.Services.Protocols.SoapHttpClientProtocol)) { Console.WriteLine(type.ToString()); foundType = type; } } object wsvcClass = results.CompiledAssembly.CreateInstance(foundType.ToString()); MethodInfo mi = wsvcClass.GetType().GetMethod(methodName); return mi.Invoke(wsvcClass, args); } else { return null; } } } This works fine when I use built in types, but for my own classes, I get this: Event Type: Error Event Source: TDX Queue Service Event Category: None Event ID: 0 Date: 12/04/2010 Time: 12:12:38 User: N/A Computer: TDXRMISDEV01 Description: System.ArgumentException: Object of type 'TDXDataTypes.AgencyOutput' cannot be converted to type 'AgencyOutput'. Server stack trace: at System.RuntimeType.CheckValue(Object value, Binder binder, CultureInfo culture, BindingFlags invokeAttr) at System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature sig) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) at TDXQueueEngine.GenericWebserviceProxy.CallWebService(String webServiceAsmxUrl, String serviceName, String methodName, Object[] args) in C:\CkAdmDev\TDXQueueEngine\TDXQueueEngine\TDXQueueEngine\GenericWebserviceProxy.cs:line 76 at TDXQueueEngine.TDXQueueWebserviceItem.Run() in C:\CkAdmDev\TDXQueueEngine\TDXQueueEngine\TDXQueueEngine\TDXQueueWebserviceItem.cs:line 99 at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs) at System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs) at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink) Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.EndInvokeHelper(Message reqMsg, Boolean bProxyCase) at System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(Object NotUsed, MessageData& msgData) at TDXQueueEngine.TDXQueue.RunProcess.EndInvoke(IAsyncResult result) at TDXQueueEngine.TDXQueue.processComplete(IAsyncResult ar) in C:\CkAdmDev\TDXQueueEngine\TDXQueueEngine\TDXQueueEngine\TDXQueue.cs:line 130 For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. The classes reference the same assembly and the same version. Do I need to include my assembly as a reference when building the temporary assembly? If so, how? Thanks.

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  • Filtering in a HierarchicalDataTemplate via MarkupExtension?

    - by Dan Bryant
    I'm trying to create a MarkupExtension to allow filtering of items in an ItemsSource of a HierarchicalDataTemplate. In particular, I'd like to be able to supply a method name that will be executed on the DataContext in order to perform the filtering. The usage syntax I'm after looks like this: <HierarchicalDataTemplate DataType="{x:Type src:DeviceBindingViewModel}" ItemsSource="{Utilities:FilterCollection {Binding Definition.Entries}, MethodName=FilterEntries}"> <StackPanel Orientation="Horizontal"> <Image Source="{StaticResource BindingImage}" Width="24" Height="24" Margin="3"/> <TextBlock Text="{Binding DisplayName}" FontSize="12" VerticalAlignment="Center"/> </StackPanel> </HierarchicalDataTemplate> My code for the custom MarkupExtension looks like this: public sealed class FilterCollectionExtension : MarkupExtension { private readonly MultiBinding _binding; private Predicate<Object> _filterMethod; public string MethodName { get; set; } public FilterCollectionExtension(Binding binding) { _binding = new MultiBinding(); _binding.Bindings.Add(binding); //We package a reference to the DataContext with the binding so that the Converter has access to it var selfBinding = new Binding {RelativeSource = RelativeSource.Self}; _binding.Bindings.Add(selfBinding); _binding.Converter = new InternalConverter(this); } public FilterCollectionExtension(Binding binding, string methodName) : this(binding) { MethodName = methodName; } public override object ProvideValue(IServiceProvider serviceProvider) { return _binding; } private bool FilterInternal(Object dataContext, Object value) { //Filtering is only applicable if a DataContext is defined if (dataContext != null) { if (_filterMethod == null) { var type = dataContext.GetType(); var method = type.GetMethod(MethodName, new[] { typeof(Object) }); if (method == null || method.ReturnType != typeof(bool)) throw new InvalidOperationException("Could not locate a filter predicate named " + MethodName + " on the DataContext"); _filterMethod = (Predicate<Object>)Delegate.CreateDelegate(typeof(Predicate<Object>), dataContext, method); } else { if (_filterMethod.Target != dataContext) { _filterMethod = (Predicate<Object>) Delegate.CreateDelegate(typeof (Predicate<Object>), dataContext, _filterMethod.Method); } } if (_filterMethod != null) return _filterMethod(value); } //If no filtering resolved, just allow all elements return true; } private class InternalConverter : IMultiValueConverter { private readonly FilterCollectionExtension _owner; public InternalConverter(FilterCollectionExtension owner) { _owner = owner; } public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture) { var enumerable = values[0]; var targetElement = (FrameworkElement)values[1]; var view = CollectionViewSource.GetDefaultView(enumerable); view.Filter = item => _owner.FilterInternal(targetElement.DataContext, item); return view; } public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture) { throw new NotSupportedException("Cannot convert back"); } } } I can see that the extension is instantiated and I can see it return the MultiBinding that is used by the Template. I also see the call to the InternalConverter.Convert method, which sees the expected parameters (I see the collection provided by the nested {Binding}) and is successfully able to retrieve the ICollectionView for the incoming collection. The only problem is that FilterInternal never gets called. The template is ultimately being used by a TreeView, if that's relevant. I haven't been able to figure out why the FilterInternal method is not being called and I was hoping somebody might be able to offer some insight.

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  • Object of type 'customObject' cannot be converted to type 'customObject'.

    - by Phani Kumar PV
    i am receiving the follwing error when i am invoking a custom object "Object of type 'customObject' cannot be converted to type 'customObject'." Following is the scenario when i am getting the error i am invoking a method in a dll dynamically. Load an assembly CreateInstance.... calling MethodInfo.Invoke() passing int, string as a parameter for my method is working fine = No exceptions are thrown. But if I try and pass a one of my own custom class objects as a parameter, then I get an ArgumentException exception, and it is not either an ArgumentOutOfRangeException or ArgumentNullException. "Object of type 'customObject' cannot be converted to type 'customObject'." I am doing this in a web application. The class file containing the method is in a different proj . also the custom object is a sepearte class in the same file. there is no such thing called a static aseembly in my code. I am trying to invoke a webmethod dynamically. this webmethod is having the customObject type as an input parameter. So when i invoke the webmethod i am dynamically creating the proxy assembly and all. From the same assembly i am trying to create an instance of the cusotm object assinging the values to its properties and then passing this object as a parameter and invoking the method. everything is dynamic and nothing is created static.. :( add reference is not used. Following is a sample code i tried to create it public static object CallWebService(string webServiceAsmxUrl, string serviceName, string methodName, object[] args) { System.Net.WebClient client = new System.Net.WebClient(); //-Connect To the web service using (System.IO.Stream stream = client.OpenRead(webServiceAsmxUrl + "?wsdl")) { //--Now read the WSDL file describing a service. ServiceDescription description = ServiceDescription.Read(stream); ///// LOAD THE DOM ///////// //--Initialize a service description importer. ServiceDescriptionImporter importer = new ServiceDescriptionImporter(); importer.ProtocolName = "Soap12"; // Use SOAP 1.2. importer.AddServiceDescription(description, null, null); //--Generate a proxy client. importer.Style = ServiceDescriptionImportStyle.Client; //--Generate properties to represent primitive values. importer.CodeGenerationOptions = System.Xml.Serialization.CodeGenerationOptions.GenerateProperties; //--Initialize a Code-DOM tree into which we will import the service. CodeNamespace nmspace = new CodeNamespace(); CodeCompileUnit unit1 = new CodeCompileUnit(); unit1.Namespaces.Add(nmspace); //--Import the service into the Code-DOM tree. This creates proxy code //--that uses the service. ServiceDescriptionImportWarnings warning = importer.Import(nmspace, unit1); if (warning == 0) //--If zero then we are good to go { //--Generate the proxy code CodeDomProvider provider1 = CodeDomProvider.CreateProvider("CSharp"); //--Compile the assembly proxy with the appropriate references string[] assemblyReferences = new string[5] { "System.dll", "System.Web.Services.dll", "System.Web.dll", "System.Xml.dll", "System.Data.dll" }; CompilerParameters parms = new CompilerParameters(assemblyReferences); CompilerResults results = provider1.CompileAssemblyFromDom(parms, unit1); //-Check For Errors if (results.Errors.Count > 0) { StringBuilder sb = new StringBuilder(); foreach (CompilerError oops in results.Errors) { sb.AppendLine("========Compiler error============"); sb.AppendLine(oops.ErrorText); } throw new System.ApplicationException("Compile Error Occured calling webservice. " + sb.ToString()); } //--Finally, Invoke the web service method Type foundType = null; Type[] types = results.CompiledAssembly.GetTypes(); foreach (Type type in types) { if (type.BaseType == typeof(System.Web.Services.Protocols.SoapHttpClientProtocol)) { Console.WriteLine(type.ToString()); foundType = type; } } object wsvcClass = results.CompiledAssembly.CreateInstance(foundType.ToString()); MethodInfo mi = wsvcClass.GetType().GetMethod(methodName); return mi.Invoke(wsvcClass, args); } else { return null; } } } I cant find anything static being done by me. any help is greatly appreciated. Regards, Phani Kumar PV

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  • Spring Security and the Synchronizer Token J2EE pattern, problem when authentication fails.

    - by dfuse
    Hey, we are using Spring Security 2.0.4. We have a TransactionTokenBean which generates a unique token each POST, the bean is session scoped. The token is used for the duplicate form submission problem (and security). The TransactionTokenBean is called from a Servlet filter. Our problem is the following, after a session timeout occured, when you do a POST in the application Spring Security redirects to the logon page, saving the original request. After logging on again the TransactionTokenBean is created again, since it is session scoped, but then Spring forwards to the originally accessed url, also sending the token that was generated at that time. Since the TransactionTokenBean is created again, the tokens do not match and our filter throws an Exception. I don't quite know how to handle this elegantly, (or for that matter, I can't even fix it with a hack), any ideas? This is the code of the TransactionTokenBean: public class TransactionTokenBean implements Serializable { public static final int TOKEN_LENGTH = 8; private RandomizerBean randomizer; private transient Logger logger; private String expectedToken; public String getUniqueToken() { return expectedToken; } public void init() { resetUniqueToken(); } public final void verifyAndResetUniqueToken(String actualToken) { verifyUniqueToken(actualToken); resetUniqueToken(); } public void resetUniqueToken() { expectedToken = randomizer.getRandomString(TOKEN_LENGTH, RandomizerBean.ALPHANUMERICS); getLogger().debug("reset token to: " + expectedToken); } public void verifyUniqueToken(String actualToken) { if (getLogger().isDebugEnabled()) { getLogger().debug("verifying token. expected=" + expectedToken + ", actual=" + actualToken); } if (expectedToken == null || actualToken == null || !isValidToken(actualToken)) { throw new IllegalArgumentException("missing or invalid transaction token"); } if (!expectedToken.equals(actualToken)) { throw new InvalidTokenException(); } } private boolean isValidToken(String actualToken) { return StringUtils.isAlphanumeric(actualToken); } public void setRandomizer(RandomizerBean randomizer) { this.randomizer = randomizer; } private Logger getLogger() { if (logger == null) { logger = Logger.getLogger(TransactionTokenBean.class); } return logger; } } and this is the Servlet filter (ignore the Ajax stuff): public class SecurityFilter implements Filter { static final String AJAX_TOKEN_PARAM = "ATXTOKEN"; static final String TOKEN_PARAM = "TXTOKEN"; private WebApplicationContext webApplicationContext; private Logger logger = Logger.getLogger(SecurityFilter.class); public void init(FilterConfig config) { setWebApplicationContext(WebApplicationContextUtils.getWebApplicationContext(config.getServletContext())); } public void destroy() { } public void doFilter(ServletRequest req, ServletResponse response, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; if (isPostRequest(request)) { if (isAjaxRequest(request)) { log("verifying token for AJAX request " + request.getRequestURI()); getTransactionTokenBean(true).verifyUniqueToken(request.getParameter(AJAX_TOKEN_PARAM)); } else { log("verifying and resetting token for non-AJAX request " + request.getRequestURI()); getTransactionTokenBean(false).verifyAndResetUniqueToken(request.getParameter(TOKEN_PARAM)); } } chain.doFilter(request, response); } private void log(String line) { if (logger.isDebugEnabled()) { logger.debug(line); } } private boolean isPostRequest(HttpServletRequest request) { return "POST".equals(request.getMethod().toUpperCase()); } private boolean isAjaxRequest(HttpServletRequest request) { return request.getParameter("AJAXREQUEST") != null; } private TransactionTokenBean getTransactionTokenBean(boolean ajax) { return (TransactionTokenBean) webApplicationContext.getBean(ajax ? "ajaxTransactionTokenBean" : "transactionTokenBean"); } void setWebApplicationContext(WebApplicationContext context) { this.webApplicationContext = context; } }

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  • Connecting Android device to multiple Bluetooth serial embedded peers

    - by TacB0sS
    I'm trying to find a solution for this setup: I have a single Android device, which I would like to connect to multiple serial embedded devices... And here is the thing, using the "Normal" way to retrieve the Bluetooth socket, doesn't work on all devices, and while it does, I can connect to multiple devices, and send and receive data to and from multiple devices. public final synchronized void connect() throws ConnectionException { if (socket != null) throw new IllegalStateException("Error socket is not null!!"); connecting = true; lastException = null; lastPacket = null; lastHeartBeatReceivedAt = 0; log.setLength(0); try { socket = fetchBT_Socket_Normal(); connectToSocket(socket); listenForIncomingSPP_Packets(); connecting = false; return; } catch (Exception e) { socket = null; logError(e); } try { socket = fetchBT_Socket_Workaround(); connectToSocket(socket); listenForIncomingSPP_Packets(); connecting = false; return; } catch (Exception e) { socket = null; logError(e); } connecting = false; if (socket == null) throw new ConnectionException("Error creating RFcomm socket for" + this); } private BluetoothSocket fetchBT_Socket_Normal() throws Exception { /* The getType() is a hex 0xXXXX value agreed between peers --- this is the key (in my case) to multiple connections in the "Normal" way */ String uuid = getType() + "1101-0000-1000-8000-00805F9B34FB"; try { logDebug("Fetching BT RFcomm Socket standard for UUID: " + uuid + "..."); socket = btDevice.createRfcommSocketToServiceRecord(UUID.fromString(uuid)); return socket; } catch (Exception e) { logError(e); throw e; } } private BluetoothSocket fetchBT_Socket_Workaround() throws Exception { Method m; int connectionIndex = 1; try { logDebug("Fetching BT RFcomm Socket workaround index " + connectionIndex + "..."); m = btDevice.getClass().getMethod("createRfcommSocket", new Class[]{int.class}); socket = (BluetoothSocket) m.invoke(btDevice, connectionIndex); return socket; } catch (Exception e1) { logError(e1); throw e1; } } private void connectToSocket(BluetoothSocket socket) throws ConnectionException { try { socket.connect(); } catch (IOException e) { try { socket.close(); } catch (IOException e1) { logError("Error while closing socket", e1); } finally { socket = null; } throw new ConnectionException("Error connecting to socket with" + this, e); } } And here is the thing, while on phones which the "Normal" way doesn't work, the "Workaround" way provides a solution for a single connection. I've searched far and wide, but came up with zip. The problem with the workaround is mentioned in the last link, both connection uses the same port, which in my case, causes a block, where both of the embedded devices can actually send data, that is not been processed on the Android, while both embedded devices can receive data sent from the Android. Did anyone handle this before? There is a bit more reference here, UPDATE: Following this (that I posted earlier) I wanted to give the mPort a chance, and perhaps to see other port indices, and how other devices manage them, and I found out the the fields in the BluetoothSocket object are different while it is the same class FQN in both cases: Detils from an HTC Vivid 2.3.4, uses the "workaround" Technic: The Socket class type is: [android.bluetooth.BluetoothSocket] mSocket BluetoothSocket (id=830008629928) EADDRINUSE 98 EBADFD 77 MAX_RFCOMM_CHANNEL 30 TAG "BluetoothSocket" (id=830002722432) TYPE_L2CAP 3 TYPE_RFCOMM 1 TYPE_SCO 2 mAddress "64:9C:8E:DC:56:9A" (id=830008516328) mAuth true mClosed false mClosing AtomicBoolean (id=830007851600) mDevice BluetoothDevice (id=830007854256) mEncrypt true mInputStream BluetoothInputStream (id=830008688856) mLock ReentrantReadWriteLock (id=830008629992) mOutputStream BluetoothOutputStream (id=830008430536) **mPort 1** mSdp null mSocketData 3923880 mType 1 Detils from an LG-P925 2.2.2, uses the "normal" Technic: The Socket class type is: [android.bluetooth.BluetoothSocket] mSocket BluetoothSocket (id=830105532880) EADDRINUSE 98 EBADFD 77 MAX_RFCOMM_CHANNEL 30 TAG "BluetoothSocket" (id=830002668088) TYPE_L2CAP 3 TYPE_RFCOMM 1 TYPE_SCO 2 mAccepted false mAddress "64:9C:8E:B9:3F:77" (id=830105544600) mAuth true mClosed false mConnected ConditionVariable (id=830105533144) mDevice BluetoothDevice (id=830105349488) mEncrypt true mInputStream BluetoothInputStream (id=830105532952) mLock ReentrantReadWriteLock (id=830105532984) mOutputStream BluetoothOutputStream (id=830105532968) mPortName "" (id=830002606256) mSocketData 0 mSppPort BluetoothSppPort (id=830105533160) mType 1 mUuid ParcelUuid (id=830105714176) Anyone have some insight...

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  • A ToDynamic() Extension Method For Fluent Reflection

    - by Dixin
    Recently I needed to demonstrate some code with reflection, but I felt it inconvenient and tedious. To simplify the reflection coding, I created a ToDynamic() extension method. The source code can be downloaded from here. Problem One example for complex reflection is in LINQ to SQL. The DataContext class has a property Privider, and this Provider has an Execute() method, which executes the query expression and returns the result. Assume this Execute() needs to be invoked to query SQL Server database, then the following code will be expected: using (NorthwindDataContext database = new NorthwindDataContext()) { // Constructs the query. IQueryable<Product> query = database.Products.Where(product => product.ProductID > 0) .OrderBy(product => product.ProductName) .Take(2); // Executes the query. Here reflection is required, // because Provider, Execute(), and ReturnValue are not public members. IEnumerable<Product> results = database.Provider.Execute(query.Expression).ReturnValue; // Processes the results. foreach (Product product in results) { Console.WriteLine("{0}, {1}", product.ProductID, product.ProductName); } } Of course, this code cannot compile. And, no one wants to write code like this. Again, this is just an example of complex reflection. using (NorthwindDataContext database = new NorthwindDataContext()) { // Constructs the query. IQueryable<Product> query = database.Products.Where(product => product.ProductID > 0) .OrderBy(product => product.ProductName) .Take(2); // database.Provider PropertyInfo providerProperty = database.GetType().GetProperty( "Provider", BindingFlags.NonPublic | BindingFlags.GetProperty | BindingFlags.Instance); object provider = providerProperty.GetValue(database, null); // database.Provider.Execute(query.Expression) // Here GetMethod() cannot be directly used, // because Execute() is a explicitly implemented interface method. Assembly assembly = Assembly.Load("System.Data.Linq"); Type providerType = assembly.GetTypes().SingleOrDefault( type => type.FullName == "System.Data.Linq.Provider.IProvider"); InterfaceMapping mapping = provider.GetType().GetInterfaceMap(providerType); MethodInfo executeMethod = mapping.InterfaceMethods.Single(method => method.Name == "Execute"); IExecuteResult executeResult = executeMethod.Invoke(provider, new object[] { query.Expression }) as IExecuteResult; // database.Provider.Execute(query.Expression).ReturnValue IEnumerable<Product> results = executeResult.ReturnValue as IEnumerable<Product>; // Processes the results. foreach (Product product in results) { Console.WriteLine("{0}, {1}", product.ProductID, product.ProductName); } } This may be not straight forward enough. So here a solution will implement fluent reflection with a ToDynamic() extension method: IEnumerable<Product> results = database.ToDynamic() // Starts fluent reflection. .Provider.Execute(query.Expression).ReturnValue; C# 4.0 dynamic In this kind of scenarios, it is easy to have dynamic in mind, which enables developer to write whatever code after a dot: using (NorthwindDataContext database = new NorthwindDataContext()) { // Constructs the query. IQueryable<Product> query = database.Products.Where(product => product.ProductID > 0) .OrderBy(product => product.ProductName) .Take(2); // database.Provider dynamic dynamicDatabase = database; dynamic results = dynamicDatabase.Provider.Execute(query).ReturnValue; } This throws a RuntimeBinderException at runtime: 'System.Data.Linq.DataContext.Provider' is inaccessible due to its protection level. Here dynamic is able find the specified member. So the next thing is just writing some custom code to access the found member. .NET 4.0 DynamicObject, and DynamicWrapper<T> Where to put the custom code for dynamic? The answer is DynamicObject’s derived class. I first heard of DynamicObject from Anders Hejlsberg's video in PDC2008. It is very powerful, providing useful virtual methods to be overridden, like: TryGetMember() TrySetMember() TryInvokeMember() etc.  (In 2008 they are called GetMember, SetMember, etc., with different signature.) For example, if dynamicDatabase is a DynamicObject, then the following code: dynamicDatabase.Provider will invoke dynamicDatabase.TryGetMember() to do the actual work, where custom code can be put into. Now create a type to inherit DynamicObject: public class DynamicWrapper<T> : DynamicObject { private readonly bool _isValueType; private readonly Type _type; private T _value; // Not readonly, for value type scenarios. public DynamicWrapper(ref T value) // Uses ref in case of value type. { if (value == null) { throw new ArgumentNullException("value"); } this._value = value; this._type = value.GetType(); this._isValueType = this._type.IsValueType; } public override bool TryGetMember(GetMemberBinder binder, out object result) { // Searches in current type's public and non-public properties. PropertyInfo property = this._type.GetTypeProperty(binder.Name); if (property != null) { result = property.GetValue(this._value, null).ToDynamic(); return true; } // Searches in explicitly implemented properties for interface. MethodInfo method = this._type.GetInterfaceMethod(string.Concat("get_", binder.Name), null); if (method != null) { result = method.Invoke(this._value, null).ToDynamic(); return true; } // Searches in current type's public and non-public fields. FieldInfo field = this._type.GetTypeField(binder.Name); if (field != null) { result = field.GetValue(this._value).ToDynamic(); return true; } // Searches in base type's public and non-public properties. property = this._type.GetBaseProperty(binder.Name); if (property != null) { result = property.GetValue(this._value, null).ToDynamic(); return true; } // Searches in base type's public and non-public fields. field = this._type.GetBaseField(binder.Name); if (field != null) { result = field.GetValue(this._value).ToDynamic(); return true; } // The specified member is not found. result = null; return false; } // Other overridden methods are not listed. } In the above code, GetTypeProperty(), GetInterfaceMethod(), GetTypeField(), GetBaseProperty(), and GetBaseField() are extension methods for Type class. For example: internal static class TypeExtensions { internal static FieldInfo GetBaseField(this Type type, string name) { Type @base = type.BaseType; if (@base == null) { return null; } return @base.GetTypeField(name) ?? @base.GetBaseField(name); } internal static PropertyInfo GetBaseProperty(this Type type, string name) { Type @base = type.BaseType; if (@base == null) { return null; } return @base.GetTypeProperty(name) ?? @base.GetBaseProperty(name); } internal static MethodInfo GetInterfaceMethod(this Type type, string name, params object[] args) { return type.GetInterfaces().Select(type.GetInterfaceMap).SelectMany(mapping => mapping.TargetMethods) .FirstOrDefault( method => method.Name.Split('.').Last().Equals(name, StringComparison.Ordinal) && method.GetParameters().Count() == args.Length && method.GetParameters().Select( (parameter, index) => parameter.ParameterType.IsAssignableFrom(args[index].GetType())).Aggregate( true, (a, b) => a && b)); } internal static FieldInfo GetTypeField(this Type type, string name) { return type.GetFields( BindingFlags.GetField | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic).FirstOrDefault( field => field.Name.Equals(name, StringComparison.Ordinal)); } internal static PropertyInfo GetTypeProperty(this Type type, string name) { return type.GetProperties( BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic).FirstOrDefault( property => property.Name.Equals(name, StringComparison.Ordinal)); } // Other extension methods are not listed. } So now, when invoked, TryGetMember() searches the specified member and invoke it. The code can be written like this: dynamic dynamicDatabase = new DynamicWrapper<NorthwindDataContext>(ref database); dynamic dynamicReturnValue = dynamicDatabase.Provider.Execute(query.Expression).ReturnValue; This greatly simplified reflection. ToDynamic() and fluent reflection To make it even more straight forward, A ToDynamic() method is provided: public static class DynamicWrapperExtensions { public static dynamic ToDynamic<T>(this T value) { return new DynamicWrapper<T>(ref value); } } and a ToStatic() method is provided to unwrap the value: public class DynamicWrapper<T> : DynamicObject { public T ToStatic() { return this._value; } } In the above TryGetMember() method, please notice it does not output the member’s value, but output a wrapped member value (that is, memberValue.ToDynamic()). This is very important to make the reflection fluent. Now the code becomes: IEnumerable<Product> results = database.ToDynamic() // Here starts fluent reflection. .Provider.Execute(query.Expression).ReturnValue .ToStatic(); // Unwraps to get the static value. With the help of TryConvert(): public class DynamicWrapper<T> : DynamicObject { public override bool TryConvert(ConvertBinder binder, out object result) { result = this._value; return true; } } ToStatic() can be omitted: IEnumerable<Product> results = database.ToDynamic() .Provider.Execute(query.Expression).ReturnValue; // Automatically converts to expected static value. Take a look at the reflection code at the beginning of this post again. Now it is much much simplified! Special scenarios In 90% of the scenarios ToDynamic() is enough. But there are some special scenarios. Access static members Using extension method ToDynamic() for accessing static members does not make sense. Instead, DynamicWrapper<T> has a parameterless constructor to handle these scenarios: public class DynamicWrapper<T> : DynamicObject { public DynamicWrapper() // For static. { this._type = typeof(T); this._isValueType = this._type.IsValueType; } } The reflection code should be like this: dynamic wrapper = new DynamicWrapper<StaticClass>(); int value = wrapper._value; int result = wrapper.PrivateMethod(); So accessing static member is also simple, and fluent of course. Change instances of value types Value type is much more complex. The main problem is, value type is copied when passing to a method as a parameter. This is why ref keyword is used for the constructor. That is, if a value type instance is passed to DynamicWrapper<T>, the instance itself will be stored in this._value of DynamicWrapper<T>. Without the ref keyword, when this._value is changed, the value type instance itself does not change. Consider FieldInfo.SetValue(). In the value type scenarios, invoking FieldInfo.SetValue(this._value, value) does not change this._value, because it changes the copy of this._value. I searched the Web and found a solution for setting the value of field: internal static class FieldInfoExtensions { internal static void SetValue<T>(this FieldInfo field, ref T obj, object value) { if (typeof(T).IsValueType) { field.SetValueDirect(__makeref(obj), value); // For value type. } else { field.SetValue(obj, value); // For reference type. } } } Here __makeref is a undocumented keyword of C#. But method invocation has problem. This is the source code of TryInvokeMember(): public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { if (binder == null) { throw new ArgumentNullException("binder"); } MethodInfo method = this._type.GetTypeMethod(binder.Name, args) ?? this._type.GetInterfaceMethod(binder.Name, args) ?? this._type.GetBaseMethod(binder.Name, args); if (method != null) { // Oops! // If the returnValue is a struct, it is copied to heap. object resultValue = method.Invoke(this._value, args); // And result is a wrapper of that copied struct. result = new DynamicWrapper<object>(ref resultValue); return true; } result = null; return false; } If the returned value is of value type, it will definitely copied, because MethodInfo.Invoke() does return object. If changing the value of the result, the copied struct is changed instead of the original struct. And so is the property and index accessing. They are both actually method invocation. For less confusion, setting property and index are not allowed on struct. Conclusions The DynamicWrapper<T> provides a simplified solution for reflection programming. It works for normal classes (reference types), accessing both instance and static members. In most of the scenarios, just remember to invoke ToDynamic() method, and access whatever you want: StaticType result = someValue.ToDynamic()._field.Method().Property[index]; In some special scenarios which requires changing the value of a struct (value type), this DynamicWrapper<T> does not work perfectly. Only changing struct’s field value is supported. The source code can be downloaded from here, including a few unit test code.

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  • Entity Framework 4.0 and DDD patterns

    - by Voice
    Hi everybody I use EntityFramework as ORM and I have simple POCO Domain Model with two base classes that represent Value Object and Entity Object Patterns (Evans). These two patterns is all about equality of two objects, so I overrode Equals and GetHashCode methods. Here are these two classes: public abstract class EntityObject<T>{ protected T _ID = default(T); public T ID { get { return _ID; } protected set { _ID = value; } } public sealed override bool Equals(object obj) { EntityObject<T> compareTo = obj as EntityObject<T>; return (compareTo != null) && ((HasSameNonDefaultIdAs(compareTo) || (IsTransient && compareTo.IsTransient)) && HasSameBusinessSignatureAs(compareTo)); } public virtual void MakeTransient() { _ID = default(T); } public bool IsTransient { get { return _ID == null || _ID.Equals(default(T)); } } public override int GetHashCode() { if (default(T).Equals(_ID)) return 0; return _ID.GetHashCode(); } private bool HasSameBusinessSignatureAs(EntityObject<T> compareTo) { return ToString().Equals(compareTo.ToString()); } private bool HasSameNonDefaultIdAs(EntityObject<T> compareTo) { return (_ID != null && !_ID.Equals(default(T))) && (compareTo._ID != null && !compareTo._ID.Equals(default(T))) && _ID.Equals(compareTo._ID); } public override string ToString() { StringBuilder str = new StringBuilder(); str.Append(" Class: ").Append(GetType().FullName); if (!IsTransient) str.Append(" ID: " + _ID); return str.ToString(); } } public abstract class ValueObject<T, U> : IEquatable<T> where T : ValueObject<T, U> { private static List<PropertyInfo> Properties { get; set; } private static Func<ValueObject<T, U>, PropertyInfo, object[], object> _GetPropValue; static ValueObject() { Properties = new List<PropertyInfo>(); var propParam = Expression.Parameter(typeof(PropertyInfo), "propParam"); var target = Expression.Parameter(typeof(ValueObject<T, U>), "target"); var indexPar = Expression.Parameter(typeof(object[]), "indexPar"); var call = Expression.Call(propParam, typeof(PropertyInfo).GetMethod("GetValue", new[] { typeof(object), typeof(object[]) }), new[] { target, indexPar }); var lambda = Expression.Lambda<Func<ValueObject<T, U>, PropertyInfo, object[], object>>(call, target, propParam, indexPar); _GetPropValue = lambda.Compile(); } public U ID { get; protected set; } public override Boolean Equals(Object obj) { if (ReferenceEquals(null, obj)) return false; if (obj.GetType() != GetType()) return false; return Equals(obj as T); } public Boolean Equals(T other) { if (ReferenceEquals(null, other)) return false; if (ReferenceEquals(this, other)) return true; foreach (var property in Properties) { var oneValue = _GetPropValue(this, property, null); var otherValue = _GetPropValue(other, property, null); if (null == oneValue && null == otherValue) return false; if (false == oneValue.Equals(otherValue)) return false; } return true; } public override Int32 GetHashCode() { var hashCode = 36; foreach (var property in Properties) { var propertyValue = _GetPropValue(this, property, null); if (null == propertyValue) continue; hashCode = hashCode ^ propertyValue.GetHashCode(); } return hashCode; } public override String ToString() { var stringBuilder = new StringBuilder(); foreach (var property in Properties) { var propertyValue = _GetPropValue(this, property, null); if (null == propertyValue) continue; stringBuilder.Append(propertyValue.ToString()); } return stringBuilder.ToString(); } protected static void RegisterProperty(Expression<Func<T, Object>> expression) { MemberExpression memberExpression; if (ExpressionType.Convert == expression.Body.NodeType) { var body = (UnaryExpression)expression.Body; memberExpression = body.Operand as MemberExpression; } else memberExpression = expression.Body as MemberExpression; if (null == memberExpression) throw new InvalidOperationException("InvalidMemberExpression"); Properties.Add(memberExpression.Member as PropertyInfo); } } Everything was OK until I tried to delete some related objects (aggregate root object with two dependent objects which was marked for cascade deletion): I've got an exception "The relationship could not be changed because one or more of the foreign-key properties is non-nullable". I googled this and found http://blog.abodit.com/2010/05/the-relationship-could-not-be-changed-because-one-or-more-of-the-foreign-key-properties-is-non-nullable/ I changed GetHashCode to base.GetHashCode() and error disappeared. But now it breaks all my code: I can't override GetHashCode for my POCO objects = I can't override Equals = I can't implement Value Object and Entity Object patters for my POCO objects. So, I appreciate any solutions, workarounds here etc.

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  • General type conversion without risking Exceptions

    - by Mongus Pong
    I am working on a control that can take a number of different datatypes (anything that implements IComparable). I need to be able to compare these with another variable passed in. If the main datatype is a DateTime, and I am passed a String, I need to attempt to convert the String to a DateTime to perform a Date comparison. if the String cannot be converted to a DateTime then do a String comparison. So I need a general way to attempt to convert from any type to any type. Easy enough, .Net provides us with the TypeConverter class. Now, the best I can work out to do to determine if the String can be converted to a DateTime is to use exceptions. If the ConvertFrom raises an exception, I know I cant do the conversion and have to do the string comparison. The following is the best I got : string theString = "99/12/2009"; DateTime theDate = new DateTime ( 2009, 11, 1 ); IComparable obj1 = theString as IComparable; IComparable obj2 = theDate as IComparable; try { TypeConverter converter = TypeDescriptor.GetConverter ( obj2.GetType () ); if ( converter.CanConvertFrom ( obj1.GetType () ) ) { Console.WriteLine ( obj2.CompareTo ( converter.ConvertFrom ( obj1 ) ) ); Console.WriteLine ( "Date comparison" ); } } catch ( FormatException ) { Console.WriteLine ( obj1.ToString ().CompareTo ( obj2.ToString () ) ); Console.WriteLine ( "String comparison" ); } Part of our standards at work state that : Exceptions should only be raised when an Exception situation - ie. an error is encountered. But this is not an exceptional situation. I need another way around it. Most variable types have a TryParse method which returns a boolean to allow you to determine if the conversion has succeeded or not. But there is no TryConvert method available to TypeConverter. CanConvertFrom only dermines if it is possible to convert between these types and doesnt consider the actual data to be converted. The IsValid method is also useless. Any ideas? EDIT I cannot use AS and IS. I do not know either data types at compile time. So I dont know what to As and Is to!!! EDIT Ok nailed the bastard. Its not as tidy as Marc Gravells, but it works (I hope). Thanks for the inpiration Marc. Will work on tidying it up when I get the time, but I've got a bit stack of bugfixes that I have to get on with. public static class CleanConverter { /// <summary> /// Stores the cache of all types that can be converted to all types. /// </summary> private static Dictionary<Type, Dictionary<Type, ConversionCache>> _Types = new Dictionary<Type, Dictionary<Type, ConversionCache>> (); /// <summary> /// Try parsing. /// </summary> /// <param name="s"></param> /// <param name="value"></param> /// <returns></returns> public static bool TryParse ( IComparable s, ref IComparable value ) { // First get the cached conversion method. Dictionary<Type, ConversionCache> type1Cache = null; ConversionCache type2Cache = null; if ( !_Types.ContainsKey ( s.GetType () ) ) { type1Cache = new Dictionary<Type, ConversionCache> (); _Types.Add ( s.GetType (), type1Cache ); } else { type1Cache = _Types[s.GetType ()]; } if ( !type1Cache.ContainsKey ( value.GetType () ) ) { // We havent converted this type before, so create a new conversion type2Cache = new ConversionCache ( s.GetType (), value.GetType () ); // Add to the cache type1Cache.Add ( value.GetType (), type2Cache ); } else { type2Cache = type1Cache[value.GetType ()]; } // Attempt the parse return type2Cache.TryParse ( s, ref value ); } /// <summary> /// Stores the method to convert from Type1 to Type2 /// </summary> internal class ConversionCache { internal bool TryParse ( IComparable s, ref IComparable value ) { if ( this._Method != null ) { // Invoke the cached TryParse method. object[] parameters = new object[] { s, value }; bool result = (bool)this._Method.Invoke ( null, parameters); if ( result ) value = parameters[1] as IComparable; return result; } else return false; } private MethodInfo _Method; internal ConversionCache ( Type type1, Type type2 ) { // Use reflection to get the TryParse method from it. this._Method = type2.GetMethod ( "TryParse", new Type[] { type1, type2.MakeByRefType () } ); } } }

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  • Fastest way to move records from a oracle DB into MS sql server after processing

    - by user347748
    Hi.. Ok this is the scenario...I have a table in Oracle that acts like a queue... A VB.net program reads the queue and calls a stored proc in MS SQL Server that processes and then inserts the message into another SQL server table and then deletes the record from the oracle table. We use a datareader to read the records from Oracle and then call the stored proc for each of the records. The program seems to be a little slow. The stored procedure itself isnt slow. The SP by itself when called in a loop can process about 2000 records in 20 seconds. BUt when called from the .Net program, the execution time is about 5 records per second. I have seen that most of the time consumed is in calling the stored procedure and waiting for it to return. Is there a better way of doing this? Here is a snippet of the actual code Function StartDataXfer() As Boolean Dim status As Boolean = False Try SqlConn.Open() OraConn.Open() c.ErrorLog(Now.ToString & "--Going to Get the messages from oracle", 1) If GetMsgsFromOracle() Then c.ErrorLog(Now.ToString & "--Got messages from oracle", 1) If ProcessMessages() Then c.ErrorLog(Now.ToString & "--Finished Processing all messages in the queue", 0) status = True Else c.ErrorLog(Now.ToString & "--Failed to Process all messages in the queue", 0) status = False End If Else status = True End If StartDataXfer = status Catch ex As Exception Finally SqlConn.Close() OraConn.Close() End Try End Function Private Function GetMsgsFromOracle() As Boolean Try OraDataAdapter = New OleDb.OleDbDataAdapter OraDataTable = New System.Data.DataTable OraSelCmd = New OleDb.OleDbCommand GetMsgsFromOracle = False With OraSelCmd .CommandType = CommandType.Text .Connection = OraConn .CommandText = GetMsgSql End With OraDataAdapter.SelectCommand = OraSelCmd OraDataAdapter.Fill(OraDataTable) If OraDataTable.Rows.Count > 0 Then GetMsgsFromOracle = True End If Catch ex As Exception GetMsgsFromOracle = False End Try End Function Private Function ProcessMessages() As Boolean Try ProcessMessages = False PrepareSQLInsert() PrepOraDel() i = 0 Dim Method As Integer Dim OraDataRow As DataRow c.ErrorLog(Now.ToString & "--Going to call message sending procedure", 2) For Each OraDataRow In OraDataTable.Rows With OraDataRow Method = GetMethod(.Item(0)) SQLInsCmd.Parameters("RelLifeTime").Value = c.RelLifetime SQLInsCmd.Parameters("Param1").Value = Nothing SQLInsCmd.Parameters("ID").Value = GenerateTransactionID() ' Nothing SQLInsCmd.Parameters("UID").Value = Nothing SQLInsCmd.Parameters("Param").Value = Nothing SQLInsCmd.Parameters("Credit").Value = 0 SQLInsCmd.ExecuteNonQuery() 'check the return value If SQLInsCmd.Parameters("ReturnValue").Value = 1 And SQLInsCmd.Parameters("OutPutParam").Value = 0 Then 'success 'delete the input record from the source table once it is logged c.ErrorLog(Now.ToString & "--Moved record successfully", 2) OraDataAdapter.DeleteCommand.Parameters("P(0)").Value = OraDataRow.Item(6) OraDataAdapter.DeleteCommand.ExecuteNonQuery() c.ErrorLog(Now.ToString & "--Deleted record successfully", 2) OraDataAdapter.Update(OraDataTable) c.ErrorLog(Now.ToString & "--Committed record successfully", 2) i = i + 1 Else 'failure c.ErrorLog(Now.ToString & "--Failed to exec: " & c.DestIns & "Status: " & SQLInsCmd.Parameters("OutPutParam").Value & " and TrackId: " & SQLInsCmd.Parameters("TrackID").Value.ToString, 0) End If If File.Exists("stop.txt") Then c.ErrorLog(Now.ToString & "--Stop File Found", 1) 'ProcessMessages = True 'Exit Function Exit For End If End With Next OraDataAdapter.Update(OraDataTable) c.ErrorLog(Now.ToString & "--Updated Oracle Table", 1) c.ErrorLog(Now.ToString & "--Moved " & i & " records from Oracle to SQL Table", 1) ProcessMessages = True Catch ex As Exception ProcessMessages = False c.ErrorLog(Now.ToString & "--MoveMsgsToSQL: " & ex.Message, 0) Finally OraDataTable.Clear() OraDataTable.Dispose() OraDataAdapter.Dispose() OraDelCmd.Dispose() OraDelCmd = Nothing OraSelCmd = Nothing OraDataTable = Nothing OraDataAdapter = Nothing End Try End Function Public Function GenerateTransactionID() As Int64 Dim SeqNo As Int64 Dim qry As String Dim SqlTransCmd As New OleDb.OleDbCommand qry = " select seqno from StoreSeqNo" SqlTransCmd.CommandType = CommandType.Text SqlTransCmd.Connection = SqlConn SqlTransCmd.CommandText = qry SeqNo = SqlTransCmd.ExecuteScalar If SeqNo > 2147483647 Then qry = "update StoreSeqNo set seqno=1" SqlTransCmd.CommandText = qry SqlTransCmd.ExecuteNonQuery() GenerateTransactionID = 1 Else qry = "update StoreSeqNo set seqno=" & SeqNo + 1 SqlTransCmd.CommandText = qry SqlTransCmd.ExecuteNonQuery() GenerateTransactionID = SeqNo End If End Function Private Function PrepareSQLInsert() As Boolean 'function to prepare the insert statement for the insert into the SQL stmt using 'the sql procedure SMSProcessAndDispatch Try Dim dr As DataRow SQLInsCmd = New OleDb.OleDbCommand With SQLInsCmd .CommandType = CommandType.StoredProcedure .Connection = SqlConn .CommandText = SQLInsProc .Parameters.Add("ReturnValue", OleDb.OleDbType.Integer) .Parameters("ReturnValue").Direction = ParameterDirection.ReturnValue .Parameters.Add("OutPutParam", OleDb.OleDbType.Integer) .Parameters("OutPutParam").Direction = ParameterDirection.Output .Parameters.Add("TrackID", OleDb.OleDbType.VarChar, 70) .Parameters.Add("RelLifeTime", OleDb.OleDbType.TinyInt) .Parameters("RelLifeTime").Direction = ParameterDirection.Input .Parameters.Add("Param1", OleDb.OleDbType.VarChar, 160) .Parameters("Param1").Direction = ParameterDirection.Input .Parameters.Add("TransID", OleDb.OleDbType.VarChar, 70) .Parameters("TransID").Direction = ParameterDirection.Input .Parameters.Add("UID", OleDb.OleDbType.VarChar, 20) .Parameters("UID").Direction = ParameterDirection.Input .Parameters.Add("Param", OleDb.OleDbType.VarChar, 160) .Parameters("Param").Direction = ParameterDirection.Input .Parameters.Add("CheckCredit", OleDb.OleDbType.Integer) .Parameters("CheckCredit").Direction = ParameterDirection.Input .Prepare() End With Catch ex As Exception c.ErrorLog(Now.ToString & "--PrepareSQLInsert: " & ex.Message) End Try End Function Private Function PrepOraDel() As Boolean OraDelCmd = New OleDb.OleDbCommand Try PrepOraDel = False With OraDelCmd .CommandType = CommandType.Text .Connection = OraConn .CommandText = DelSrcSQL .Parameters.Add("P(0)", OleDb.OleDbType.VarChar, 160) 'RowID .Parameters("P(0)").Direction = ParameterDirection.Input .Prepare() End With OraDataAdapter.DeleteCommand = OraDelCmd PrepOraDel = True Catch ex As Exception PrepOraDel = False End Try End Function WHat i would like to know is, if there is anyway to speed up this program? Any ideas/suggestions would be highly appreciated... Regardss, Chetan

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  • Fastest way to move records from an Oracle database into SQL Server

    - by user347748
    Ok this is the scenario... I have a table in Oracle that acts like a queue... A VB.net program reads the queue and calls a stored proc in SQL Server that processes and then inserts the message into another SQL Server table and then deletes the record from the oracle table. We use a DataReader to read the records from Oracle and then call the stored proc for each of the records. The program seems to be a little slow. The stored procedure itself isn't slow. The SP by itself when called in a loop can process about 2000 records in 20 seconds. But when called from the .Net program, the execution time is about 5 records per second. I have seen that most of the time consumed is in calling the stored procedure and waiting for it to return. Is there a better way of doing this? Here is a snippet of the actual code Function StartDataXfer() As Boolean Dim status As Boolean = False Try SqlConn.Open() OraConn.Open() c.ErrorLog(Now.ToString & "--Going to Get the messages from oracle", 1) If GetMsgsFromOracle() Then c.ErrorLog(Now.ToString & "--Got messages from oracle", 1) If ProcessMessages() Then c.ErrorLog(Now.ToString & "--Finished Processing all messages in the queue", 0) status = True Else c.ErrorLog(Now.ToString & "--Failed to Process all messages in the queue", 0) status = False End If Else status = True End If StartDataXfer = status Catch ex As Exception Finally SqlConn.Close() OraConn.Close() End Try End Function Private Function GetMsgsFromOracle() As Boolean Try OraDataAdapter = New OleDb.OleDbDataAdapter OraDataTable = New System.Data.DataTable OraSelCmd = New OleDb.OleDbCommand GetMsgsFromOracle = False With OraSelCmd .CommandType = CommandType.Text .Connection = OraConn .CommandText = GetMsgSql End With OraDataAdapter.SelectCommand = OraSelCmd OraDataAdapter.Fill(OraDataTable) If OraDataTable.Rows.Count > 0 Then GetMsgsFromOracle = True End If Catch ex As Exception GetMsgsFromOracle = False End Try End Function Private Function ProcessMessages() As Boolean Try ProcessMessages = False PrepareSQLInsert() PrepOraDel() i = 0 Dim Method As Integer Dim OraDataRow As DataRow c.ErrorLog(Now.ToString & "--Going to call message sending procedure", 2) For Each OraDataRow In OraDataTable.Rows With OraDataRow Method = GetMethod(.Item(0)) SQLInsCmd.Parameters("RelLifeTime").Value = c.RelLifetime SQLInsCmd.Parameters("Param1").Value = Nothing SQLInsCmd.Parameters("ID").Value = GenerateTransactionID() ' Nothing SQLInsCmd.Parameters("UID").Value = Nothing SQLInsCmd.Parameters("Param").Value = Nothing SQLInsCmd.Parameters("Credit").Value = 0 SQLInsCmd.ExecuteNonQuery() 'check the return value If SQLInsCmd.Parameters("ReturnValue").Value = 1 And SQLInsCmd.Parameters("OutPutParam").Value = 0 Then 'success 'delete the input record from the source table once it is logged c.ErrorLog(Now.ToString & "--Moved record successfully", 2) OraDataAdapter.DeleteCommand.Parameters("P(0)").Value = OraDataRow.Item(6) OraDataAdapter.DeleteCommand.ExecuteNonQuery() c.ErrorLog(Now.ToString & "--Deleted record successfully", 2) OraDataAdapter.Update(OraDataTable) c.ErrorLog(Now.ToString & "--Committed record successfully", 2) i = i + 1 Else 'failure c.ErrorLog(Now.ToString & "--Failed to exec: " & c.DestIns & "Status: " & SQLInsCmd.Parameters("OutPutParam").Value & " and TrackId: " & SQLInsCmd.Parameters("TrackID").Value.ToString, 0) End If If File.Exists("stop.txt") Then c.ErrorLog(Now.ToString & "--Stop File Found", 1) 'ProcessMessages = True 'Exit Function Exit For End If End With Next OraDataAdapter.Update(OraDataTable) c.ErrorLog(Now.ToString & "--Updated Oracle Table", 1) c.ErrorLog(Now.ToString & "--Moved " & i & " records from Oracle to SQL Table", 1) ProcessMessages = True Catch ex As Exception ProcessMessages = False c.ErrorLog(Now.ToString & "--MoveMsgsToSQL: " & ex.Message, 0) Finally OraDataTable.Clear() OraDataTable.Dispose() OraDataAdapter.Dispose() OraDelCmd.Dispose() OraDelCmd = Nothing OraSelCmd = Nothing OraDataTable = Nothing OraDataAdapter = Nothing End Try End Function Public Function GenerateTransactionID() As Int64 Dim SeqNo As Int64 Dim qry As String Dim SqlTransCmd As New OleDb.OleDbCommand qry = " select seqno from StoreSeqNo" SqlTransCmd.CommandType = CommandType.Text SqlTransCmd.Connection = SqlConn SqlTransCmd.CommandText = qry SeqNo = SqlTransCmd.ExecuteScalar If SeqNo > 2147483647 Then qry = "update StoreSeqNo set seqno=1" SqlTransCmd.CommandText = qry SqlTransCmd.ExecuteNonQuery() GenerateTransactionID = 1 Else qry = "update StoreSeqNo set seqno=" & SeqNo + 1 SqlTransCmd.CommandText = qry SqlTransCmd.ExecuteNonQuery() GenerateTransactionID = SeqNo End If End Function Private Function PrepareSQLInsert() As Boolean 'function to prepare the insert statement for the insert into the SQL stmt using 'the sql procedure SMSProcessAndDispatch Try Dim dr As DataRow SQLInsCmd = New OleDb.OleDbCommand With SQLInsCmd .CommandType = CommandType.StoredProcedure .Connection = SqlConn .CommandText = SQLInsProc .Parameters.Add("ReturnValue", OleDb.OleDbType.Integer) .Parameters("ReturnValue").Direction = ParameterDirection.ReturnValue .Parameters.Add("OutPutParam", OleDb.OleDbType.Integer) .Parameters("OutPutParam").Direction = ParameterDirection.Output .Parameters.Add("TrackID", OleDb.OleDbType.VarChar, 70) .Parameters.Add("RelLifeTime", OleDb.OleDbType.TinyInt) .Parameters("RelLifeTime").Direction = ParameterDirection.Input .Parameters.Add("Param1", OleDb.OleDbType.VarChar, 160) .Parameters("Param1").Direction = ParameterDirection.Input .Parameters.Add("TransID", OleDb.OleDbType.VarChar, 70) .Parameters("TransID").Direction = ParameterDirection.Input .Parameters.Add("UID", OleDb.OleDbType.VarChar, 20) .Parameters("UID").Direction = ParameterDirection.Input .Parameters.Add("Param", OleDb.OleDbType.VarChar, 160) .Parameters("Param").Direction = ParameterDirection.Input .Parameters.Add("CheckCredit", OleDb.OleDbType.Integer) .Parameters("CheckCredit").Direction = ParameterDirection.Input .Prepare() End With Catch ex As Exception c.ErrorLog(Now.ToString & "--PrepareSQLInsert: " & ex.Message) End Try End Function Private Function PrepOraDel() As Boolean OraDelCmd = New OleDb.OleDbCommand Try PrepOraDel = False With OraDelCmd .CommandType = CommandType.Text .Connection = OraConn .CommandText = DelSrcSQL .Parameters.Add("P(0)", OleDb.OleDbType.VarChar, 160) 'RowID .Parameters("P(0)").Direction = ParameterDirection.Input .Prepare() End With OraDataAdapter.DeleteCommand = OraDelCmd PrepOraDel = True Catch ex As Exception PrepOraDel = False End Try End Function WHat i would like to know is, if there is anyway to speed up this program? Any ideas/suggestions would be highly appreciated... Regardss, Chetan

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  • Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors

    - by SeanMcAlinden
    Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design For the latest code go to http://rapidioc.codeplex.com/ When building our proxy type, the first thing we need to do is build the constructors. There needs to be a corresponding constructor for each constructor on the passed in base type. We also want to create a field to store the interceptors and construct this list within each constructor. So assuming the passed in base type is a User<int, IRepository> class, were looking to generate constructor code like the following:   Default Constructor public User`2_RapidDynamicBaseProxy() {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }     Parameterised Constructor public User`2_RapidDynamicBaseProxy(IRepository repository1) : base(repository1) {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }   As you can see, we first populate a field on the class with a new list of the passed in base type. Construct our DefaultInterceptor class. Add the DefaultInterceptor instance to our interceptor collection. Although this seems like a relatively small task, there is a fair amount of work require to get this going. Instead of going through every line of code – please download the latest from http://rapidioc.codeplex.com/ and debug through. In this post I’m going to concentrate on explaining how it works. TypeBuilder The TypeBuilder class is the main class used to create the type. You instantiate a new TypeBuilder using the assembly module we created in part 1. /// <summary> /// Creates a type builder. /// </summary> /// <typeparam name="TBase">The type of the base class to be proxied.</typeparam> public static TypeBuilder CreateTypeBuilder<TBase>() where TBase : class {     TypeBuilder typeBuilder = DynamicModuleCache.Get.DefineType         (             CreateTypeName<TBase>(),             TypeAttributes.Class | TypeAttributes.Public,             typeof(TBase),             new Type[] { typeof(IProxy) }         );       if (typeof(TBase).IsGenericType)     {         GenericsHelper.MakeGenericType(typeof(TBase), typeBuilder);     }       return typeBuilder; }   private static string CreateTypeName<TBase>() where TBase : class {     return string.Format("{0}_RapidDynamicBaseProxy", typeof(TBase).Name); } As you can see, I’ve create a new public class derived from TBase which also implements my IProxy interface, this is used later for adding interceptors. If the base type is generic, the following GenericsHelper.MakeGenericType method is called. GenericsHelper using System; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Types.Helpers {     /// <summary>     /// Helper class for generic types and methods.     /// </summary>     internal static class GenericsHelper     {         /// <summary>         /// Makes the typeBuilder a generic.         /// </summary>         /// <param name="concrete">The concrete.</param>         /// <param name="typeBuilder">The type builder.</param>         public static void MakeGenericType(Type baseType, TypeBuilder typeBuilder)         {             Type[] genericArguments = baseType.GetGenericArguments();               string[] genericArgumentNames = GetArgumentNames(genericArguments);               GenericTypeParameterBuilder[] genericTypeParameterBuilder                 = typeBuilder.DefineGenericParameters(genericArgumentNames);               typeBuilder.MakeGenericType(genericTypeParameterBuilder);         }           /// <summary>         /// Gets the argument names from an array of generic argument types.         /// </summary>         /// <param name="genericArguments">The generic arguments.</param>         public static string[] GetArgumentNames(Type[] genericArguments)         {             string[] genericArgumentNames = new string[genericArguments.Length];               for (int i = 0; i < genericArguments.Length; i++)             {                 genericArgumentNames[i] = genericArguments[i].Name;             }               return genericArgumentNames;         }     } }       As you can see, I’m getting all of the generic argument types and names, creating a GenericTypeParameterBuilder and then using the typeBuilder to make the new type generic. InterceptorsField The interceptors field will store a List<IInterceptor<TBase>>. Fields are simple made using the FieldBuilder class. The following code demonstrates how to create the interceptor field. FieldBuilder interceptorsField = typeBuilder.DefineField(     "interceptors",     typeof(System.Collections.Generic.List<>).MakeGenericType(typeof(IInterceptor<TBase>)),       FieldAttributes.Private     ); The field will now exist with the new Type although it currently has no data – we’ll deal with this in the constructor. Add method for interceptorsField To enable us to add to the interceptorsField list, we are going to utilise the Add method that already exists within the System.Collections.Generic.List class. We still however have to create the methodInfo necessary to call the add method. This can be done similar to the following: Add Interceptor Field MethodInfo addInterceptor = typeof(List<>)     .MakeGenericType(new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) })     .GetMethod     (        "Add",        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) },        null     ); So we’ve create a List<IInterceptor<TBase>> type, then using the type created a method info called Add which accepts an IInterceptor<TBase>. Now in our constructor we can use this to call this.interceptors.Add(// interceptor); Building the Constructors This will be the first hard-core part of the proxy building process so I’m going to show the class and then try to explain what everything is doing. For a clear view, download the source from http://rapidioc.codeplex.com/, go to the test project and debug through the constructor building section. Anyway, here it is: DynamicConstructorBuilder using System; using System.Collections.Generic; using System.Reflection; using System.Reflection.Emit; using Rapid.DynamicProxy.Interception; using Rapid.DynamicProxy.Types.Helpers; namespace Rapid.DynamicProxy.Types.Constructors {     /// <summary>     /// Class for creating the proxy constructors.     /// </summary>     internal static class DynamicConstructorBuilder     {         /// <summary>         /// Builds the constructors.         /// </summary>         /// <typeparam name="TBase">The base type.</typeparam>         /// <param name="typeBuilder">The type builder.</param>         /// <param name="interceptorsField">The interceptors field.</param>         public static void BuildConstructors<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 MethodInfo addInterceptor             )             where TBase : class         {             ConstructorInfo interceptorsFieldConstructor = CreateInterceptorsFieldConstructor<TBase>();               ConstructorInfo defaultInterceptorConstructor = CreateDefaultInterceptorConstructor<TBase>();               ConstructorInfo[] constructors = typeof(TBase).GetConstructors();               foreach (ConstructorInfo constructorInfo in constructors)             {                 CreateConstructor<TBase>                     (                         typeBuilder,                         interceptorsField,                         interceptorsFieldConstructor,                         defaultInterceptorConstructor,                         addInterceptor,                         constructorInfo                     );             }         }           #region Private Methods           private static void CreateConstructor<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ConstructorInfo defaultInterceptorConstructor,                 MethodInfo AddDefaultInterceptor,                 ConstructorInfo constructorInfo             ) where TBase : class         {             Type[] parameterTypes = GetParameterTypes(constructorInfo);               ConstructorBuilder constructorBuilder = CreateConstructorBuilder(typeBuilder, parameterTypes);               ILGenerator cIL = constructorBuilder.GetILGenerator();               LocalBuilder defaultInterceptorMethodVariable =                 cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase)));               ConstructInterceptorsField(interceptorsField, interceptorsFieldConstructor, cIL);               ConstructDefaultInterceptor(defaultInterceptorConstructor, cIL, defaultInterceptorMethodVariable);               AddDefaultInterceptorToInterceptorsList                 (                     interceptorsField,                     AddDefaultInterceptor,                     cIL,                     defaultInterceptorMethodVariable                 );               CreateConstructor(constructorInfo, parameterTypes, cIL);         }           private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         }           private static void AddDefaultInterceptorToInterceptorsList             (                 FieldBuilder interceptorsField,                 MethodInfo AddDefaultInterceptor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Ldfld, interceptorsField);             cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);             cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor);         }           private static void ConstructDefaultInterceptor             (                 ConstructorInfo defaultInterceptorConstructor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);             cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable);         }           private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         }           private static ConstructorBuilder CreateConstructorBuilder(TypeBuilder typeBuilder, Type[] parameterTypes)         {             return typeBuilder.DefineConstructor                 (                     MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName                     | MethodAttributes.HideBySig, CallingConventions.Standard, parameterTypes                 );         }           private static Type[] GetParameterTypes(ConstructorInfo constructorInfo)         {             ParameterInfo[] parameterInfoArray = constructorInfo.GetParameters();               Type[] parameterTypes = new Type[parameterInfoArray.Length];               for (int p = 0; p < parameterInfoArray.Length; p++)             {                 parameterTypes[p] = parameterInfoArray[p].ParameterType;             }               return parameterTypes;         }           private static ConstructorInfo CreateInterceptorsFieldConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(List<>),                     new Type[] { typeof(IInterceptor<TBase>) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           private static ConstructorInfo CreateDefaultInterceptorConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(DefaultInterceptor<>),                     new Type[] { typeof(TBase) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           #endregion     } } So, the first two tasks within the class should be fairly clear, we are creating a ConstructorInfo for the interceptorField list and a ConstructorInfo for the DefaultConstructor, this is for instantiating them in each contructor. We then using Reflection get an array of all of the constructors in the base class, we then loop through the array and create a corresponding proxy contructor. Hopefully, the code is fairly easy to follow other than some new types and the dreaded Opcodes. ConstructorBuilder This class defines a new constructor on the type. ILGenerator The ILGenerator allows the use of Reflection.Emit to create the method body. LocalBuilder The local builder allows the storage of data in local variables within a method, in this case it’s the constructed DefaultInterceptor. Constructing the interceptors field The first bit of IL you’ll come across as you follow through the code is the following private method used for constructing the field list of interceptors. private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         } The first thing to know about generating code using IL is that you are using a stack, if you want to use something, you need to push it up the stack etc. etc. OpCodes.ldArg_0 This opcode is a really interesting one, basically each method has a hidden first argument of the containing class instance (apart from static classes), constructors are no different. This is the reason you can use syntax like this.myField. So back to the method, as we want to instantiate the List in the interceptorsField, first we need to load the class instance onto the stack, we then load the new object (new List<TBase>) and finally we store it in the interceptorsField. Hopefully, that should follow easily enough in the method. In each constructor you would now have this.interceptors = new List<User<int, IRepository>>(); Constructing and storing the DefaultInterceptor The next bit of code we need to create is the constructed DefaultInterceptor. Firstly, we create a local builder to store the constructed type. Create a local builder LocalBuilder defaultInterceptorMethodVariable =     cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase))); Once our local builder is ready, we then need to construct the DefaultInterceptor<TBase> and store it in the variable. Connstruct DefaultInterceptor private static void ConstructDefaultInterceptor     (         ConstructorInfo defaultInterceptorConstructor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);     cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable); } As you can see, using the ConstructorInfo named defaultInterceptorConstructor, we load the new object onto the stack. Then using the store local opcode (OpCodes.Stloc), we store the new object in the local builder named defaultInterceptorMethodVariable. Add the constructed DefaultInterceptor to the interceptors field collection Using the add method created earlier in this post, we are going to add the new DefaultInterceptor object to the interceptors field collection. Add Default Interceptor private static void AddDefaultInterceptorToInterceptorsList     (         FieldBuilder interceptorsField,         MethodInfo AddDefaultInterceptor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Ldarg_0);     cIL.Emit(OpCodes.Ldfld, interceptorsField);     cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);     cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor); } So, here’s whats going on. The class instance is first loaded onto the stack using the load argument at index 0 opcode (OpCodes.Ldarg_0) (remember the first arg is the hidden class instance). The interceptorsField is then loaded onto the stack using the load field opcode (OpCodes.Ldfld). We then load the DefaultInterceptor object we stored locally using the load local opcode (OpCodes.Ldloc). Then finally we call the AddDefaultInterceptor method using the call virtual opcode (Opcodes.Callvirt). Completing the constructor The last thing we need to do is complete the constructor. Complete the constructor private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         } So, the first thing we do again is load the class instance using the load argument at index 0 opcode (OpCodes.Ldarg_0). We then load each parameter using OpCode.Ldarg_S, this opcode allows us to specify an index position for each argument. We then setup calling the base constructor using OpCodes.Call and the base constructors ConstructorInfo. Finally, all methods are required to return, even when they have a void return. As there are no values on the stack after the OpCodes.Call line, we can safely call the OpCode.Ret to give the constructor a void return. If there was a value, we would have to pop the value of the stack before calling return otherwise, the method would try and return a value. Conclusion This was a slightly hardcore post but hopefully it hasn’t been too hard to follow. The main thing is that a number of the really useful opcodes have been used and now the dynamic proxy is capable of being constructed. If you download the code and debug through the tests at http://rapidioc.codeplex.com/, you’ll be able to create proxies at this point, they cannon do anything in terms of interception but you can happily run the tests, call base methods and properties and also take a look at the created assembly in Reflector. Hope this is useful. The next post should be up soon, it will be covering creating the private methods for calling the base class methods and properties. Kind Regards, Sean.

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