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  • Help me construct this Linq statement

    - by Geoffrey
    There should be a simple Linq query for what I'm trying to accomplish, but I'm producing some ugly code. I have two tables, one of issues and another of issue status. There is a one-to-many relationship between issue and issue status. When an issue is created an IssueStatus is also created with the status field set to "Open" when it is closed, another IssueStatus is created with the status field set to "Closed" ... but issues can be re-opened. It seems like I should be able to write something like this: public static List<Issue> FindOpenIssues(this IList<Issue> issues) { return ( from issue in issues from issueStatus in issue.issueStatus.OrderBy(x=>x.CreatedOn).Single() where issueStatus.Status == "Open" select issue ).ToList(); } This obviously fails, but there must be a clean way to do this? Thanks!

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  • No supported translation to SQL

    - by derans
    We have this code: private IList<InfoRequest> GetBy(Func<InformationRequest, string> func, string searchby) { var requests = _dc.InformationRequests .Where(x => func.Invoke(x).Contains(searchby)) .OrderBy(y => y.RequestDate); return Mapper.Map<InformationRequest[], InfoRequest[]>(requests.ToArray()); } It continues to throw the no supported translation to SQL error. Any ideas on the problem or how to resolve it?

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  • get look up a string given a func<T,object> param

    - by Sammy
    given this code namespace GridTests { public class Grid<T> { IEnumerable<T> DataSource { get; set; } IList<Column> Columns = new List<Column>(); class Column { public string DisplayText { get; set; } Func<T, object> Rowdata { get; set; } } } } I need to be able to loop through the columns collection and get the Rowdata's object value using the DisplayText. Thanks

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  • Error message regarding IEnumerable.GetEnumerator().

    - by Bon_chan
    I get this error message and I can't figure out why! Error 1 'Exo5Chap12.ShortCollection<T>' does not implement interface member 'System.Collections.IEnumerable.GetEnumerator()'. 'Exo5Chap12.ShortCollection<T>.GetEnumerator()' cannot implement 'System.Collections.IEnumerable.GetEnumerator()' because it does not have the matching return type of 'System.Collections.IEnumerator'. E:\MyFolders\Dev\c#\Chapter12\Exo5Chap12\Exo5Chap12\exo5.cs 9 18 Exo5Chap12 Here is the code with an implementation of GetEnumerator(). What is wrong? public class ShortCollection<T> : IList<T> { protected Collection<T> innerCollection; protected int maxSize = 10; public IEnumerator<T> GetEnumerator() { return (innerCollection as IEnumerator<T>).GetEnumerator(); } }

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  • Increase application performance

    - by Prayos
    I'm writing a program for a company that will generate a daily report for them. All of the data that they use for this report is stored in a local SQLite database. For this report, the utilize pretty much every bit of the information in the database. So currently, when I query the datbase, I retrieve everything, and store the information in lists. Here's what I've got: using (var dataReader = _connection.Select(query)) { if (dataReader.HasRows) { while (dataReader.Read()) { _date.Add(Convert.ToDateTime(dataReader["date"])); _measured.Add(Convert.ToDouble(dataReader["measured_dist"])); _bit.Add(Convert.ToDouble(dataReader["bit_loc"])); _psi.Add(Convert.ToDouble(dataReader["pump_press"])); _time.Add(Convert.ToDateTime(dataReader["timestamp"])); _fob.Add(Convert.ToDouble(dataReader["force_on_bit"])); _torque.Add(Convert.ToDouble(dataReader["torque"])); _rpm.Add(Convert.ToDouble(dataReader["rpm"])); _pumpOneSpm.Add(Convert.ToDouble(dataReader["pump_1_strokes_pm"])); _pumpTwoSpm.Add(Convert.ToDouble(dataReader["pump_2_strokes_pm"])); _pullForce.Add(Convert.ToDouble(dataReader["pull_force"])); _gpm.Add(Convert.ToDouble(dataReader["flow"])); } } } I then utilize these lists for the calculations. Obviously, the more information that is in this database, the longer the initial query will take. I'm curious if there is a way to increase the performance of the query at all? Thanks for any and all help. EDIT One of the report rows is called Daily Drilling Hours. For this calculation, I use this method: // Retrieves the timestamps where measured depth == bit depth and PSI >= 50 public double CalculateDailyProjectDrillingHours(DateTime date) { var dailyTimeStamps = _time.Where((t, i) => _date[i].Equals(date) && _measured[i].Equals(_bit[i]) && _psi[i] >= 50).ToList(); return _dailyDrillingHours = Convert.ToDouble(Math.Round(TimeCalculations(dailyTimeStamps).TotalHours, 2, MidpointRounding.AwayFromZero)); } // Checks that the interval is less than 10, then adds the interval to the total time private static TimeSpan TimeCalculations(IList<DateTime> timeStamps) { var interval = new TimeSpan(0, 0, 10); var totalTime = new TimeSpan(); TimeSpan timeDifference; for (var j = 0; j < timeStamps.Count - 1; j++) { if (timeStamps[j + 1].Subtract(timeStamps[j]) <= interval) { timeDifference = timeStamps[j + 1].Subtract(timeStamps[j]); totalTime = totalTime.Add(timeDifference); } } return totalTime; }

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  • Question on design of current pagination implementations

    - by Freshblood
    I have checked pagination implementations on asp.net mvc specifically and i really feel that there is something less efficient in implementations. First of all all implementations use pagination values like below. public ActionResult MostPopulars(int pageIndex,int pageSize) { } The thing that i feel wrong is pageIndex and pageSize totally should be member of Pagination class otherwise this way looks so much functional way. Also it simplify unnecesary paramater pass in tiers of application. Second thing is that they use below interface. public interface IPagedList<T> : IList<T> { int PageCount { get; } int TotalItemCount { get; } int PageIndex { get; } int PageNumber { get; } int PageSize { get; } bool HasPreviousPage { get; } bool HasNextPage { get; } bool IsFirstPage { get; } bool IsLastPage { get; } } If i want to routing my pagination to different action so i have to create new view model for encapsulate action name in it or even controller name. Another solution can be that sending this interfaced model to view then specify action and controller hard coded in pager method as parameter but i am losing totally re-usability of my view because it is strictly depends on just one action. Another thing is that they use below code in view Html.Pager(Model.PageSize, Model.PageNumber, Model.TotalItemCount) If the model is IPagedList why they don't provide an overload method like @Html.Pager(Model) or even better one is @Html.Pager(). You know that we know model type in this way. Before i was doing mistake because i was using Model.PageIndex instead of Model.PageNumber. Another big issue is they strongly rely on IQueryable interface. How they know that i use IQueryable in my data layer ? I would expected that they work simply with collections that is keep pagination implementation persistence ignorant. What is wrong about my improvement ideas over their pagination implementations ? What is their reason to not implement their paginations in this way ?

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  • Unit Testing with NUnit and Moles Redux

    - by João Angelo
    Almost two years ago, when Moles was still being packaged alongside Pex, I wrote a post on how to run NUnit tests supporting moled types. A lot has changed since then and Moles is now being distributed independently of Pex, but maintaining support for integration with NUnit and other testing frameworks. For NUnit the support is provided by an addin class library (Microsoft.Moles.NUnit.dll) that you need to reference in your test project so that you can decorate yours tests with the MoledAttribute. The addin DLL must also be placed in the addins folder inside the NUnit installation directory. There is however a downside, since Moles and NUnit follow a different release cycle and the addin DLL must be built against a specific NUnit version, you may find that the release included with the latest version of Moles does not work with your version of NUnit. Fortunately the code for building the NUnit addin is supplied in the archive (moles.samples.zip) that you can found in the Documentation folder inside the Moles installation directory. By rebuilding the addin against your specific version of NUnit you are able to support any version. Also to note that in Moles 0.94.51023.0 the addin code did not support the use of TestCaseAttribute in your moled tests. However, if you need this support, you need to make just a couple of changes. Change the ITestDecorator.Decorate method in the MolesAddin class: Test ITestDecorator.Decorate(Test test, MemberInfo member) { SafeDebug.AssumeNotNull(test, "test"); SafeDebug.AssumeNotNull(member, "member"); bool isTestFixture = true; isTestFixture &= test.IsSuite; isTestFixture &= test.FixtureType != null; bool hasMoledAttribute = true; hasMoledAttribute &= !SafeArray.IsNullOrEmpty( member.GetCustomAttributes(typeof(MoledAttribute), false)); if (!isTestFixture && hasMoledAttribute) { return new MoledTest(test); } return test; } Change the Tests property in the MoledTest class: public override System.Collections.IList Tests { get { if (this.test.Tests == null) { return null; } var moled = new List<Test>(this.test.Tests.Count); foreach (var test in this.test.Tests) { moled.Add(new MoledTest((Test)test)); } return moled; } } Disclaimer: I only tested this implementation against NUnit 2.5.10.11092 version. Finally you just need to run the NUnit console runner through the Moles runner. A quick example follows: moles.runner.exe [Tests.dll] /r:nunit-console.exe /x86 /args:[NUnitArgument1] /args:[NUnitArgument2]

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  • Is There a Real Advantage to Generic Repository?

    - by Sam
    Was reading through some articles on the advantages of creating Generic Repositories for a new app (example). The idea seems nice because it lets me use the same repository to do several things for several different entity types at once: IRepository repo = new EfRepository(); // Would normally pass through IOC into constructor var c1 = new Country() { Name = "United States", CountryCode = "US" }; var c2 = new Country() { Name = "Canada", CountryCode = "CA" }; var c3 = new Country() { Name = "Mexico", CountryCode = "MX" }; var p1 = new Province() { Country = c1, Name = "Alabama", Abbreviation = "AL" }; var p2 = new Province() { Country = c1, Name = "Alaska", Abbreviation = "AK" }; var p3 = new Province() { Country = c2, Name = "Alberta", Abbreviation = "AB" }; repo.Add<Country>(c1); repo.Add<Country>(c2); repo.Add<Country>(c3); repo.Add<Province>(p1); repo.Add<Province>(p2); repo.Add<Province>(p3); repo.Save(); However, the rest of the implementation of the Repository has a heavy reliance on Linq: IQueryable<T> Query(); IList<T> Find(Expression<Func<T,bool>> predicate); T Get(Expression<Func<T,bool>> predicate); T First(Expression<Func<T,bool>> predicate); //... and so on This repository pattern worked fantastic for Entity Framework, and pretty much offered a 1 to 1 mapping of the methods available on DbContext/DbSet. But given the slow uptake of Linq on other data access technologies outside of Entity Framework, what advantage does this provide over working directly with the DbContext? I attempted to write a PetaPoco version of the Repository, but PetaPoco doesn't support Linq Expressions, which makes creating a generic IRepository interface pretty much useless unless you only use it for the basic GetAll, GetById, Add, Update, Delete, and Save methods and utilize it as a base class. Then you have to create specific repositories with specialized methods to handle all the "where" clauses that I could previously pass in as a predicate. Is the Generic Repository pattern useful for anything outside of Entity Framework? If not, why would someone use it at all instead of working directly with Entity Framework? Edit: Original link doesn't reflect the pattern I was using in my sample code. Here is an (updated link).

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  • OData &ndash; The easiest service I can create

    - by Jon Dalberg
    I wanted to create an OData service with the least amount of code so I fired up Visual Studio and got cracking. I decided to serve up a list of naughty words and make them read-only. Create a new web project. I created an empty MVC 2 application but MVC is not required for OData. Add a new WCF Data Service to the project. I named mine NastyWords.svc since I’m serving up a list of nasty words. Add a class to expose via the service: NastyWord 1: [DataServiceKey("Word")] 2: public class NastyWord 3: { 4: public string Word { get; set; } 5: }   I need to be able to uniquely identify instances of NastyWords for the DataService so I used the DataServiceKey attribute with the “Word” property as the key. I could have added an “ID” property which would have uniquely identified them and would then not need the “DataServiceKey” attribute because the DataService would apply some reflection and heuristics to guess at which property would be the unique identifier. However, the words themselves are unique so adding an “ID” property would be redundantly repetitive. Then I created a data source to expose my NastyWord objects to the service. This is just a simple class with IQueryable<T> properties exposing the entities for my service: 1: public class NastyWordsDataSource 2: { 3: private static IList<NastyWord> words = new List<NastyWord> 4: { 5: new NastyWord{ Word="crap"}, 6: new NastyWord{ Word="darn"}, 7: new NastyWord{ Word="hell"}, 8: new NastyWord{ Word="shucks"} 9: }; 10:   11: public NastyWordsDataSource() 12: { 13: NastyWords = words.AsQueryable(); 14: } 15:   16: public IQueryable<NastyWord> NastyWords { get; private set; } 17: }   Now I can go to the NastyWords.svc class and tell it which data source to use and which entities to expose: 1: public class NastyWords : DataService<NastyWordsDataSource> 2: { 3: // This method is called only once to initialize service-wide policies. 4: public static void InitializeService(DataServiceConfiguration config) 5: { 6: config.SetEntitySetAccessRule("*", EntitySetRights.AllRead); 7: config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; 8: } 9: }   Compile and browse to my NastWords.svc and weep with joy Now I can query my service just like any other OData service. Next time, I’ll modify this service to allow updates to sent so I can build up my list of nasty words. Enjoy!

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  • StackOverflowException throws often when .net application built with Debug mode

    - by user1487950
    I have an application which access an external webservice often, when i are trying to debug it, means debuging in vistual studio. it often throws out StackOverflowException at the webserverice call point. when building in Release mode , the exception thrown out only occasionally. I checked the call stack, looks like there is no recursive call. can you please suggest? thank you very much. call statck attached. [In a sleep, wait, or join] mscorlib.dll!System.Threading.WaitHandle.InternalWaitOne(System.Runtime.InteropServices.SafeHandle waitableSafeHandle, long millisecondsTimeout, bool hasThreadAffinity, bool exitContext) + 0x2b bytes mscorlib.dll!System.Threading.WaitHandle.WaitOne(int millisecondsTimeout, bool exitContext) + 0x2d bytes System.dll!System.Net.NetworkAddressChangePolled.CheckAndReset() + 0x9d bytes System.dll!System.Net.NclUtilities.LocalAddresses.get() + 0x49 bytes System.dll!System.Net.WebProxyScriptHelper.myIpAddress() + 0x27 bytes [Native to Managed Transition] System.dll!System.Net.WebProxyScriptHelper.MyMethodInfo.Invoke(object target, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, object[] args, System.Globalization.CultureInfo culture) + 0x6b bytes MTOqoHCT.dll!JScript 0.myIpAddress(object this, Microsoft.JScript.Vsa.VsaEngine vsa Engine, object arguments) + 0x91 bytes MTOqoHCT.dll!JScript 0.FindProxyForURL(object this, Microsoft.JScript.Vsa.VsaEngine vsa Engine, object arguments, object url, object host) + 0x3c6e bytes MTOqoHCT.dll!__WebProxyScript.__WebProxyScript.ExecuteFindProxyForURL(object url, object host) + 0x11d bytes [Native to Managed Transition] Microsoft.JScript.dll!System.Net.VsaWebProxyScript.CallMethod(object targetObject, string name, object[] args) + 0x11a bytes Microsoft.JScript.dll!System.Net.VsaWebProxyScript.Run(string url, string host) + 0x74 bytes [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage msg, int methodPtr, bool fExecuteInContext) + 0x1ef bytes mscorlib.dll!System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage msg) + 0xf bytes mscorlib.dll!System.Runtime.Remoting.Messaging.ServerObjectTerminatorSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0x66 bytes mscorlib.dll!System.Runtime.Remoting.Messaging.ServerContextTerminatorSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0x8a bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossContextChannel.SyncProcessMessageCallback(object[] args) + 0x94 bytes mscorlib.dll!System.Threading.Thread.CompleteCrossContextCallback(System.Threading.InternalCrossContextDelegate ftnToCall, object[] args) + 0x8 bytes [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.Runtime.Remoting.Channels.CrossContextChannel.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0xa7 bytes mscorlib.dll!System.Runtime.Remoting.Channels.ChannelServices.SyncDispatchMessage(System.Runtime.Remoting.Messaging.IMessage msg) + 0x92 bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.DoDispatch(byte[] reqStmBuff, System.Runtime.Remoting.Messaging.SmuggledMethodCallMessage smuggledMcm, out System.Runtime.Remoting.Messaging.SmuggledMethodReturnMessage smuggledMrm) + 0xed bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.DoTransitionDispatchCallback(object[] args) + 0x8a bytes mscorlib.dll!System.Threading.Thread.CompleteCrossContextCallback(System.Threading.InternalCrossContextDelegate ftnToCall, object[] args) + 0x8 bytes [Appdomain Transition] mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.DoTransitionDispatch(byte[] reqStmBuff, System.Runtime.Remoting.Messaging.SmuggledMethodCallMessage smuggledMcm, out System.Runtime.Remoting.Messaging.SmuggledMethodReturnMessage smuggledMrm) + 0x74 bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0xa3 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RemotingProxy.CallProcessMessage(System.Runtime.Remoting.Messaging.IMessageSink ms, System.Runtime.Remoting.Messaging.IMessage reqMsg, System.Runtime.Remoting.Contexts.ArrayWithSize proxySinks, System.Threading.Thread currentThread, System.Runtime.Remoting.Contexts.Context currentContext, bool bSkippingContextChain) + 0x50 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RemotingProxy.InternalInvoke(System.Runtime.Remoting.Messaging.IMethodCallMessage reqMcmMsg, bool useDispatchMessage, int callType) + 0x1d5 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0x66 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(ref System.Runtime.Remoting.Proxies.MessageData msgData, int type) + 0xee bytes System.dll!System.Net.NetWebProxyFinder.GetProxies(System.Uri destination, out System.Collections.Generic.IList<string> proxyList) + 0x83 bytes System.dll!System.Net.AutoWebProxyScriptEngine.GetProxies(System.Uri destination, out System.Collections.Generic.IList<string> proxyList, ref int syncStatus) + 0x84 bytes System.dll!System.Net.WebProxy.GetProxiesAuto(System.Uri destination, ref int syncStatus) + 0x2e bytes System.dll!System.Net.ProxyScriptChain.GetNextProxy(out System.Uri proxy) + 0x2e bytes System.dll!System.Net.ProxyChain.ProxyEnumerator.MoveNext() + 0x98 bytes System.dll!System.Net.ServicePointManager.FindServicePoint(System.Uri address, System.Net.IWebProxy proxy, out System.Net.ProxyChain chain, ref System.Net.HttpAbortDelegate abortDelegate, ref int abortState) + 0x120 bytes System.dll!System.Net.HttpWebRequest.FindServicePoint(bool forceFind) + 0xb1 bytes System.dll!System.Net.HttpWebRequest.GetRequestStream(out System.Net.TransportContext context) + 0x247 bytes System.dll!System.Net.HttpWebRequest.GetRequestStream() + 0xe bytes System.Web.Services.dll!System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(string methodName, object[] parameters) + 0xc0 bytes Gfinet.Config.dll!Gfinet.Config.Service.cfg_webservice.addOrUpdateProperties(string string, int intVal, Gfinet.Config.Service.PropertiesDataM[] propertiesDataMs) + 0xa3 bytes Gfinet.Config.dll!Gfinet.Config.Service.WSServiceImpl.AddOrUpdateProperties(int setId, Gfinet.Config.Service.PropertiesDataM[] properties) + 0x46 bytes [Native to Managed Transition] Gfinet.Config.dll!Gfinet.Config.Service.ServiceAspect.InvocationHandler(object target, System.Reflection.MethodBase method, object[] parameters) + 0x49e bytes Gfinet.Config.dll!Gfinet.Config.DynamicProxy.DynamicProxyImpl.Invoke(System.Runtime.Remoting.Messaging.IMessage message) + 0x110 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(ref System.Runtime.Remoting.Proxies.MessageData msgData, int type) + 0xee bytes Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.StoreElement(string application, string category, string id, string elementValue, bool save) Line 303 + 0x55 bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.SaveAllInternal() Line 582 + 0x6e bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.SaveAll(bool async) Line 434 + 0x8 bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.SaveAll() Line 406 + 0xa bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Container.Persistor.Save() Line 59 + 0xc bytes C# Spark.exe!Tici.Kraps.RibbonShell.OnBtnSaveWorkspaceItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e) Line 642 + 0xf bytes C# DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItem.OnClick(DevExpress.XtraBars.BarItemLink link) + 0x108 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarBaseButtonItem.OnClick(DevExpress.XtraBars.BarItemLink link) + 0x47 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItemLink.OnLinkClick() + 0x245 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItemLink.OnLinkAction(DevExpress.XtraBars.BarLinkAction action, object actionArgs) + 0xb3 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarButtonItemLink.OnLinkAction(DevExpress.XtraBars.BarLinkAction action, object actionArgs) + 0x47e bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItemLink.OnLinkActionCore(DevExpress.XtraBars.BarLinkAction action, object actionArgs) + 0x82 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.ViewInfo.BarSelectionInfo.ClickLink(DevExpress.XtraBars.BarItemLink link) + 0x85 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.ViewInfo.BarSelectionInfo.UnPressLink(DevExpress.XtraBars.BarItemLink link) + 0x1e5 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.BaseRibbonHandler.OnUnPressItem(DevExpress.Utils.DXMouseEventArgs e, DevExpress.XtraBars.Ribbon.ViewInfo.RibbonHitInfo hitInfo) + 0xa7 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.BaseRibbonHandler.OnUnPress(DevExpress.Utils.DXMouseEventArgs e, DevExpress.XtraBars.Ribbon.ViewInfo.RibbonHitInfo hitInfo) + 0x5f bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.BaseRibbonHandler.OnMouseUp(DevExpress.Utils.DXMouseEventArgs e) + 0x19a bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.RibbonHandler.OnMouseUp(DevExpress.Utils.DXMouseEventArgs e) + 0x47 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.RibbonControl.OnMouseUp(System.Windows.Forms.MouseEventArgs e) + 0x95 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.WmMouseUp(ref System.Windows.Forms.Message m, System.Windows.Forms.MouseButtons button, int clicks) + 0x2d1 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m) + 0x93a bytes DevExpress.Utils.v11.2.dll!DevExpress.Utils.Controls.ControlBase.WndProc(ref System.Windows.Forms.Message m) + 0x81 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.RibbonControl.WndProc(ref System.Windows.Forms.Message m) + 0x85 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) + 0x13 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m) + 0x31 bytes System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.Callback(System.IntPtr hWnd, int msg, System.IntPtr wparam, System.IntPtr lparam) + 0x96 bytes [Native to Managed Transition] [Managed to Native Transition] DevExpress.Utils.v11.2.dll!DevExpress.Utils.Win.Hook.ControlWndHook.WindowProc(System.IntPtr hWnd, int message, System.IntPtr wParam, System.IntPtr lParam) + 0x159 bytes [Native to Managed Transition] [Managed to Native Transition] System.Windows.Forms.dll!System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(System.IntPtr dwComponentID, int reason, int pvLoopData) + 0x287 bytes System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(int reason, System.Windows.Forms.ApplicationContext context) + 0x16c bytes System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessageLoop(int reason, System.Windows.Forms.ApplicationContext context) + 0x61 bytes System.Windows.Forms.dll!System.Windows.Forms.Application.Run(System.Windows.Forms.Form mainForm) + 0x31 bytes Tici.Kraps.Services.dll!Tici.Kraps.Services.Container.DefaultApplicationRunner.Run() Line 41 + 0x17 bytes C# Kraps.exe!Tici.Kraps.Program.Main() Line 105 + 0x9 bytes C# [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.AppDomain.ExecuteAssembly(string assemblyFile, System.Security.Policy.Evidence assemblySecurity, string[] args) + 0x6d bytes Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() + 0x2a bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart_Context(object state) + 0x63 bytes mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool ignoreSyncCtx) + 0xb0 bytes mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x2c bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x44 bytes [Native to Managed Transition]

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  • Many to Many delete in NHibernate two parents with common association

    - by Joshua Grippo
    I have 3 top level entities in my app: Circuit, Issue, Document Circuits can contain Documents and Issues can contain Documents. When I delete a Circuit, I want it to delete the documents associated with it, unless it is used by something else. I would like this same behavior with Issues. I have it working when the only association is in the same table in the db, but if it is in another table, then it fails due to foreign key constraints. ex 1(This will cascade properly, because there is only a foreign constraint from Circuit to Document) Document1 exists. Circuit1 exists and contains a reference to Document1. If I delete Circuit1 then it deletes Document1 with it. ex 2(This will cascade properly, because there is only a foreign constraint from Circuit to Document.) Document1 exists. Circuit1 exists and contains a reference to Document1. Circuit2 exists and contains a reference to Document1. If I delete Circuit1 then it is deleted, but Document1 is not deleted because Circuit2 exists. If I then delete Circuit2, then Document1 is deleted. ex 3(This will throw an error, because when it deletes the Circuit it sees that there are no other circuits that reference the document so it tries to delete the document. However it should not, because there is an Issue that has a foreign constraint to the document.) Document 1 exists. Circuit1 exists and contains a reference to Document1. Issue1 exists and contains a reference to Document1. If I delete Circuit1, then it fails, because it tries to delete Document1, but Issues1 still has a reference. DB: This think won't let upload an image, so here is the ERD to the DB: http://lh3.ggpht.com/_jZWhe7NXay8/TROJhOd7qlI/AAAAAAAAAGU/rkni3oEANvc/CircuitIssues.gif Model: public class Circuit { public virtual int CircuitID { get; set; } public virtual string CJON { get; set; } public virtual IList<Document> Documents { get; set; } } public class Issue { public virtual int IssueID { get; set; } public virtual string Summary { get; set; } public virtual IList<Model.Document> Documents { get; set; } } public class Document { public virtual int DocumentID { get; set; } public virtual string Data { get; set; } } Mapping Files: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Model" assembly="Model"> <class name="Circuit" table="Circuit"> <id name="CircuitID"> <column name="CircuitID" not-null="true"/> <generator class="identity" /> </id> <property name="CJON" column="CJON" type="string" not-null="true"/> <bag name="Documents" table="CircuitDocument" cascade="save-update,delete-orphan"> <key column="CircuitID"/> <many-to-many class="Document"> <column name="DocumentID" not-null="true"/> </many-to-many> </bag> </class> </hibernate-mapping> <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Model" assembly="Model"> <class name="Issue" table="Issue"> <id name="IssueID"> <column name="IssueID" not-null="true"/> <generator class="identity" /> </id> <property name="Summary" column="Summary" type="string" not-null="true"/> <bag name="Documents" table="IssueDocument" cascade="save-update,delete-orphan"> <key column="IssueID"/> <many-to-many class="Document"> <column name="DocumentID" not-null="true"/> </many-to-many> </bag> </class> </hibernate-mapping> <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Model" assembly="Model"> <class name="Document" table="Document"> <id name="DocumentID"> <column name="DocumentID" not-null="true"/> <generator class="identity" /> </id> <property name="Data" column="Data" type="string" not-null="true"/> </class> </hibernate-mapping> Code: using (ISession session = sessionFactory.OpenSession()) { var doc = new Model.Document() { Data = "Doc" }; var circuit = new Model.Circuit() { CJON = "circ" }; circuit.Documents = new List<Model.Document>(new Model.Document[] { doc }); var issue = new Model.Issue() { Summary = "iss" }; issue.Documents = new List<Model.Document>(new Model.Document[] { doc }); session.Save(circuit); session.Save(issue); session.Flush(); } using (ISession session = sessionFactory.OpenSession()) { foreach (var item in session.CreateCriteria<Model.Circuit>().List<Model.Circuit>()) { session.Delete(item); } //this flush fails, because there is a reference to a child document from issue session.Flush(); foreach (var item in session.CreateCriteria<Model.Issue>().List<Model.Issue>()) { session.Delete(item); } session.Flush(); }

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  • Building applications with WPF, MVVM and Prism(aka CAG)

    - by skjagini
    In this article I am going to walk through an application using WPF and Prism (aka composite application guidance, CAG) which simulates engaging a taxi (cab).  The rules are simple, the app would have3 screens A login screen to authenticate the user An information screen. A screen to engage the cab and roam around and calculating the total fare Metered Rate of Fare The meter is required to be engaged when a cab is occupied by anyone $3.00 upon entry $0.35 for each additional unit The unit fare is: one-fifth of a mile, when the cab is traveling at 6 miles an hour or more; or 60 seconds when not in motion or traveling at less than 12 miles per hour. Night surcharge of $.50 after 8:00 PM & before 6:00 AM Peak hour Weekday Surcharge of $1.00 Monday - Friday after 4:00 PM & before 8:00 PM New York State Tax Surcharge of $.50 per ride. Example: Friday (2010-10-08) 5:30pm Start at Lexington Ave & E 57th St End at Irving Pl & E 15th St Start = $3.00 Travels 2 miles at less than 6 mph for 15 minutes = $3.50 Travels at more than 12 mph for 5 minutes = $1.75 Peak hour Weekday Surcharge = $1.00 (ride started at 5:30 pm) New York State Tax Surcharge = $0.50 Before we dive into the app, I would like to give brief description about the framework.  If you want to jump on to the source code, scroll all the way to the end of the post. MVVM MVVM pattern is in no way related to the usage of PRISM in your application and should be considered if you are using WPF irrespective of PRISM or not. Lets say you are not familiar with MVVM, your typical UI would involve adding some UI controls like text boxes, a button, double clicking on the button,  generating event handler, calling a method from business layer and updating the user interface, it works most of the time for developing small scale applications. The problem with this approach is that there is some amount of code specific to business logic wrapped in UI specific code which is hard to unit test it, mock it and MVVM helps to solve the exact problem. MVVM stands for Model(M) – View(V) – ViewModel(VM),  based on the interactions with in the three parties it should be called VVMM,  MVVM sounds more like MVC (Model-View-Controller) so the name. Why it should be called VVMM: View – View Model - Model WPF allows to create user interfaces using XAML and MVVM takes it to the next level by allowing complete separation of user interface and business logic. In WPF each view will have a property, DataContext when set to an instance of a class (which happens to be your view model) provides the data the view is interested in, i.e., view interacts with view model and at the same time view model interacts with view through DataContext. Sujith, if view and view model are interacting directly with each other how does MVVM is helping me separation of concerns? Well, the catch is DataContext is of type Object, since it is of type object view doesn’t know exact type of view model allowing views and views models to be loosely coupled. View models aggregate data from models (data access layer, services, etc) and make it available for views through properties, methods etc, i.e., View Models interact with Models. PRISM Prism is provided by Microsoft Patterns and Practices team and it can be downloaded from codeplex for source code,  samples and documentation on msdn.  The name composite implies, to compose user interface from different modules (views) without direct dependencies on each other, again allowing  loosely coupled development. Well Sujith, I can already do that with user controls, why shall I learn another framework?  That’s correct, you can decouple using user controls, but you still have to manage some amount of coupling, like how to do you communicate between the controls, how do you subscribe/unsubscribe, loading/unloading views dynamically. Prism is not a replacement for user controls, provides the following features which greatly help in designing the composite applications. Dependency Injection (DI)/ Inversion of Control (IoC) Modules Regions Event Aggregator  Commands Simply put, MVVM helps building a single view and Prism helps building an application using the views There are other open source alternatives to Prism, like MVVMLight, Cinch, take a look at them as well. Lets dig into the source code.  1. Solution The solution is made of the following projects Framework: Holds the common functionality in building applications using WPF and Prism TaxiClient: Start up project, boot strapping and app styling TaxiCommon: Helps with the business logic TaxiModules: Holds the meat of the application with views and view models TaxiTests: To test the application 2. DI / IoC Dependency Injection (DI) as the name implies refers to injecting dependencies and Inversion of Control (IoC) means the calling code has no direct control on the dependencies, opposite of normal way of programming where dependencies are passed by caller, i.e inversion; aside from some differences in terminology the concept is same in both the cases. The idea behind DI/IoC pattern is to reduce the amount of direct coupling between different components of the application, the higher the dependency the more tightly coupled the application resulting in code which is hard to modify, unit test and mock.  Initializing Dependency Injection through BootStrapper TaxiClient is the starting project of the solution and App (App.xaml)  is the starting class that gets called when you run the application. From the App’s OnStartup method we will invoke BootStrapper.   namespace TaxiClient { /// <summary> /// Interaction logic for App.xaml /// </summary> public partial class App : Application { protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e);   (new BootStrapper()).Run(); } } } BootStrapper is your contact point for initializing the application including dependency injection, creating Shell and other frameworks. We are going to use Unity for DI and there are lot of open source DI frameworks like Spring.Net, StructureMap etc with different feature set  and you can choose a framework based on your preferences. Note that Prism comes with in built support for Unity, for example we are deriving from UnityBootStrapper in our case and for any other DI framework you have to extend the Prism appropriately   namespace TaxiClient { public class BootStrapper: UnityBootstrapper { protected override IModuleCatalog CreateModuleCatalog() { return new ConfigurationModuleCatalog(); } protected override DependencyObject CreateShell() { Framework.FrameworkBootStrapper.Run(Container, Application.Current.Dispatcher);   Shell shell = new Shell(); shell.ResizeMode = ResizeMode.NoResize; shell.Show();   return shell; } } } Lets take a look into  FrameworkBootStrapper to check out how to register with unity container. namespace Framework { public class FrameworkBootStrapper { public static void Run(IUnityContainer container, Dispatcher dispatcher) { UIDispatcher uiDispatcher = new UIDispatcher(dispatcher); container.RegisterInstance<IDispatcherService>(uiDispatcher);   container.RegisterType<IInjectSingleViewService, InjectSingleViewService>( new ContainerControlledLifetimeManager());   . . . } } } In the above code we are registering two components with unity container. You shall observe that we are following two different approaches, RegisterInstance and RegisterType.  With RegisterInstance we are registering an existing instance and the same instance will be returned for every request made for IDispatcherService   and with RegisterType we are requesting unity container to create an instance for us when required, i.e., when I request for an instance for IInjectSingleViewService, unity will create/return an instance of InjectSingleViewService class and with RegisterType we can configure the life time of the instance being created. With ContaienrControllerLifetimeManager, the unity container caches the instance and reuses for any subsequent requests, without recreating a new instance. Lets take a look into FareViewModel.cs and it’s constructor. The constructor takes one parameter IEventAggregator and if you try to find all references in your solution for IEventAggregator, you will not find a single location where an instance of EventAggregator is passed directly to the constructor. The compiler still finds an instance and works fine because Prism is already configured when used with Unity container to return an instance of EventAggregator when requested for IEventAggregator and in this particular case it is called constructor injection. public class FareViewModel:ObservableBase, IDataErrorInfo { ... private IEventAggregator _eventAggregator;   public FareViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; InitializePropertyNames(); InitializeModel(); PropertyChanged += OnPropertyChanged; } ... 3. Shell Shells are very similar in operation to Master Pages in asp.net or MDI in Windows Forms. And shells contain regions which display the views, you can have as many regions as you wish in a given view. You can also nest regions. i.e, one region can load a view which in itself may contain other regions. We have to create a shell at the start of the application and are doing it by overriding CreateShell method from BootStrapper From the following Shell.xaml you shall notice that we have two content controls with Region names as ‘MenuRegion’ and ‘MainRegion’.  The idea here is that you can inject any user controls into the regions dynamically, i.e., a Menu User Control for MenuRegion and based on the user action you can load appropriate view into MainRegion.    <Window x:Class="TaxiClient.Shell" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Regions="clr-namespace:Microsoft.Practices.Prism.Regions;assembly=Microsoft.Practices.Prism" Title="Taxi" Height="370" Width="800"> <Grid Margin="2"> <ContentControl Regions:RegionManager.RegionName="MenuRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />   <ContentControl Grid.Row="1" Regions:RegionManager.RegionName="MainRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" /> <!--<Border Grid.ColumnSpan="2" BorderThickness="2" CornerRadius="3" BorderBrush="LightBlue" />-->   </Grid> </Window> 4. Modules Prism provides the ability to build composite applications and modules play an important role in it. For example if you are building a Mortgage Loan Processor application with 3 components, i.e. customer’s credit history,  existing mortgages, new home/loan information; and consider that the customer’s credit history component involves gathering data about his/her address, background information, job details etc. The idea here using Prism modules is to separate the implementation of these 3 components into their own visual studio projects allowing to build components with no dependency on each other and independently. If we need to add another component to the application, the component can be developed by in house team or some other team in the organization by starting with a new Visual Studio project and adding to the solution at the run time with very little knowledge about the application. Prism modules are defined by implementing the IModule interface and each visual studio project to be considered as a module should implement the IModule interface.  From the BootStrapper.cs you shall observe that we are overriding the method by returning a ConfiguratingModuleCatalog which returns the modules that are registered for the application using the app.config file  and you can also add module using code. Lets take a look into configuration file.   <?xml version="1.0"?> <configuration> <configSections> <section name="modules" type="Microsoft.Practices.Prism.Modularity.ModulesConfigurationSection, Microsoft.Practices.Prism"/> </configSections> <modules> <module assemblyFile="TaxiModules.dll" moduleType="TaxiModules.ModuleInitializer, TaxiModules" moduleName="TaxiModules"/> </modules> </configuration> Here we are adding TaxiModules project to our solution and TaxiModules.ModuleInitializer implements IModule interface   5. Module Mapper With Prism modules you can dynamically add or remove modules from the regions, apart from that Prism also provides API to control adding/removing the views from a region within the same module. Taxi Information Screen: Engage the Taxi Screen: The sample application has two screens, ‘Taxi Information’ and ‘Engage the Taxi’ and they both reside in same module, TaxiModules. ‘Engage the Taxi’ is again made of two user controls, FareView on the left and TotalView on the right. We have created a Shell with two regions, MenuRegion and MainRegion with menu loaded into MenuRegion. We can create a wrapper user control called EngageTheTaxi made of FareView and TotalView and load either TaxiInfo or EngageTheTaxi into MainRegion based on the user action. Though it will work it tightly binds the user controls and for every combination of user controls, we need to create a dummy wrapper control to contain them. Instead we can apply the principles we learned so far from Shell/regions and introduce another template (LeftAndRightRegionView.xaml) made of two regions Region1 (left) and Region2 (right) and load  FareView and TotalView dynamically.  To help with loading of the views dynamically I have introduce an helper an interface, IInjectSingleViewService,  idea suggested by Mike Taulty, a must read blog for .Net developers. using System; using System.Collections.Generic; using System.ComponentModel;   namespace Framework.PresentationUtility.Navigation {   public interface IInjectSingleViewService : INotifyPropertyChanged { IEnumerable<CommandViewDefinition> Commands { get; } IEnumerable<ModuleViewDefinition> Modules { get; }   void RegisterViewForRegion(string commandName, string viewName, string regionName, Type viewType); void ClearViewFromRegion(string viewName, string regionName); void RegisterModule(string moduleName, IList<ModuleMapper> moduleMappers); } } The Interface declares three methods to work with views: RegisterViewForRegion: Registers a view with a particular region. You can register multiple views and their regions under one command.  When this particular command is invoked all the views registered under it will be loaded into their regions. ClearViewFromRegion: To unload a specific view from a region. RegisterModule: The idea is when a command is invoked you can load the UI with set of controls in their default position and based on the user interaction, you can load different contols in to different regions on the fly.  And it is supported ModuleViewDefinition and ModuleMappers as shown below. namespace Framework.PresentationUtility.Navigation { public class ModuleViewDefinition { public string ModuleName { get; set; } public IList<ModuleMapper> ModuleMappers; public ICommand Command { get; set; } }   public class ModuleMapper { public string ViewName { get; set; } public string RegionName { get; set; } public Type ViewType { get; set; } } } 6. Event Aggregator Prism event aggregator enables messaging between components as in Observable pattern, Notifier notifies the Observer which receives notification it is interested in. When it comes to Observable pattern, Observer has to unsubscribes for notifications when it no longer interested in notifications, which allows the Notifier to remove the Observer’s reference from it’s local cache. Though .Net has managed garbage collection it cannot remove inactive the instances referenced by an active instance resulting in memory leak, keeping the Observers in memory as long as Notifier stays in memory.  Developers have to be very careful to unsubscribe when necessary and it often gets overlooked, to overcome these problems Prism Event Aggregator uses weak references to cache the reference (Observer in this case)  and releases the reference (memory) once the instance goes out of scope. Using event aggregator is very simple, declare a generic type of CompositePresenationEvent by inheriting from it. using Microsoft.Practices.Prism.Events; using TaxiCommon.BAO;   namespace TaxiCommon.CompositeEvents { public class TaxiOnMoveEvent:CompositePresentationEvent<TaxiOnMove> { } }   TaxiOnMove.cs includes the properties which we want to exchange between the parties, FareView and TotalView. using System;   namespace TaxiCommon.BAO { public class TaxiOnMove { public TimeSpan MinutesAtTweleveMPH { get; set; } public double MilesAtSixMPH { get; set; } } }   Lets take a look into FareViewodel (Notifier) and how it raises the event.  Here we are raising the event by getting the event through GetEvent<..>() and publishing it with the payload private void OnAddMinutes(object obj) { TaxiOnMove payload = new TaxiOnMove(); if(MilesAtSixMPH != null) payload.MilesAtSixMPH = MilesAtSixMPH.Value; if(MinutesAtTweleveMPH != null) payload.MinutesAtTweleveMPH = new TimeSpan(0,0,MinutesAtTweleveMPH.Value,0);   _eventAggregator.GetEvent<TaxiOnMoveEvent>().Publish(payload); ResetMinutesAndMiles(); } And TotalViewModel(Observer) subscribes to notifications by getting the event through GetEvent<..>() namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { .... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; ... }   private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>() .Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>() .Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>() .Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   ... private void OnTaxiMove(TaxiOnMove taxiOnMove) { OnMoveFare fare = new OnMoveFare(taxiOnMove); Fares.Add(fare); SetTotalFare(new []{fare}); }   .... 7. MVVM through example In this section we are going to look into MVVM implementation through example.  I have all the modules declared in a single project, TaxiModules, again it is not necessary to have them into one project. Once the user logs into the application, will be greeted with the ‘Engage the Taxi’ screen which is made of two user controls, FareView.xaml and TotalView.Xaml. As you can see from the solution explorer, each of them have their own code behind files and  ViewModel classes, FareViewMode.cs, TotalViewModel.cs Lets take a look in to the FareView and how it interacts with FareViewModel using MVVM implementation. FareView.xaml acts as a view and FareViewMode.cs is it’s view model. The FareView code behind class   namespace TaxiModules.Views { /// <summary> /// Interaction logic for FareView.xaml /// </summary> public partial class FareView : UserControl { public FareView(FareViewModel viewModel) { InitializeComponent(); this.Loaded += (s, e) => { this.DataContext = viewModel; }; } } } The FareView is bound to FareViewModel through the data context  and you shall observe that DataContext is of type Object, i.e. the FareView doesn’t really know the type of ViewModel (FareViewModel). This helps separation of View and ViewModel as View and ViewModel are independent of each other, you can bind FareView to FareViewModel2 as well and the application compiles just fine. Lets take a look into FareView xaml file  <UserControl x:Class="TaxiModules.Views.FareView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Toolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" xmlns:Commands="clr-namespace:Microsoft.Practices.Prism.Commands;assembly=Microsoft.Practices.Prism"> <Grid Margin="10" > ....   <Border Style="{DynamicResource innerBorder}" Grid.Row="0" Grid.Column="0" Grid.RowSpan="11" Grid.ColumnSpan="2" Panel.ZIndex="1"/>   <Label Grid.Row="0" Content="Engage the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="1" Content="Select the State"/> <ComboBox Grid.Row="1" Grid.Column="1" ItemsSource="{Binding States}" Height="auto"> <ComboBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> </DataTemplate> </ComboBox.ItemTemplate> <ComboBox.SelectedItem> <Binding Path="SelectedState" Mode="TwoWay"/> </ComboBox.SelectedItem> </ComboBox> <Label Grid.Row="2" Content="Select the Date of Entry"/> <Toolkit:DatePicker Grid.Row="2" Grid.Column="1" SelectedDate="{Binding DateOfEntry, ValidatesOnDataErrors=true}" /> <Label Grid.Row="3" Content="Enter time 24hr format"/> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding TimeOfEntry, TargetNullValue=''}"/> <Button Grid.Row="4" Grid.Column="1" Content="Start the Meter" Commands:Click.Command="{Binding StartMeterCommand}" />   <Label Grid.Row="5" Content="Run the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="6" Content="Number of Miles &lt;@6mph"/> <TextBox Grid.Row="6" Grid.Column="1" Text="{Binding MilesAtSixMPH, TargetNullValue='', ValidatesOnDataErrors=true}"/> <Label Grid.Row="7" Content="Number of Minutes @12mph"/> <TextBox Grid.Row="7" Grid.Column="1" Text="{Binding MinutesAtTweleveMPH, TargetNullValue=''}"/> <Button Grid.Row="8" Grid.Column="1" Content="Add Minutes and Miles " Commands:Click.Command="{Binding AddMinutesCommand}"/> <Label Grid.Row="9" Content="Other Operations" Style="{DynamicResource innerHeader}"/> <Button Grid.Row="10" Grid.Column="1" Content="Reset the Meter" Commands:Click.Command="{Binding ResetCommand}"/>   </Grid> </UserControl> The highlighted code from the above code shows data binding, for example ComboBox which displays list of states has it’s ItemsSource bound to States property, with DataTemplate bound to Name and SelectedItem  to SelectedState. You might be wondering what are all these properties and how it is able to bind to them.  The answer lies in data context, i.e., when you bound a control, WPF looks for data context on the root object (Grid in this case) and if it can’t find data context it will look into root’s root, i.e. FareView UserControl and it is bound to FareViewModel.  Each of those properties have be declared on the ViewModel for the View to bind correctly. To put simply, View is bound to ViewModel through data context of type object and every control that is bound on the View actually binds to the public property on the ViewModel. Lets look into the ViewModel code (the following code is not an exact copy of FareViewMode.cs, pasted relevant code for this section)   namespace TaxiModules.ViewModels { public class FareViewModel:ObservableBase, IDataErrorInfo { public List<USState> States { get { return USStates.StateList; } }   public USState SelectedState { get { return _selectedState; } set { _selectedState = value; RaisePropertyChanged(_selectedStatePropertyName); } }   public DateTime? DateOfEntry { get { return _dateOfEntry; } set { _dateOfEntry = value; RaisePropertyChanged(_dateOfEntryPropertyName); } }   public TimeSpan? TimeOfEntry { get { return _timeOfEntry; } set { _timeOfEntry = value; RaisePropertyChanged(_timeOfEntryPropertyName); } }   public double? MilesAtSixMPH { get { return _milesAtSixMPH; } set { _milesAtSixMPH = value; RaisePropertyChanged(_distanceAtSixMPHPropertyName); } }   public int? MinutesAtTweleveMPH { get { return _minutesAtTweleveMPH; } set { _minutesAtTweleveMPH = value; RaisePropertyChanged(_minutesAtTweleveMPHPropertyName); } }   public ICommand StartMeterCommand { get { if(_startMeterCommand == null) { _startMeterCommand = new DelegateCommand<object>(OnStartMeter, CanStartMeter); } return _startMeterCommand; } }   public ICommand AddMinutesCommand { get { if(_addMinutesCommand == null) { _addMinutesCommand = new DelegateCommand<object>(OnAddMinutes, CanAddMinutes); } return _addMinutesCommand; } }   public ICommand ResetCommand { get { if(_resetCommand == null) { _resetCommand = new DelegateCommand<object>(OnResetCommand); } return _resetCommand; } }   } private void OnStartMeter(object obj) { _eventAggregator.GetEvent<TaxiStartedEvent>().Publish( new TaxiStarted() { EngagedOn = DateOfEntry.Value.Date + TimeOfEntry.Value, EngagedState = SelectedState.Value });   _isMeterStarted = true; OnPropertyChanged(this,null); } And views communicate user actions like button clicks, tree view item selections, etc using commands. When user clicks on ‘Start the Meter’ button it invokes the method StartMeterCommand, which calls the method OnStartMeter which publishes the event to TotalViewModel using event aggregator  and TaxiStartedEvent. namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { ... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator;   InitializePropertyNames(); InitializeModel(); SubscribeToEvents(); }   public decimal? TotalFare { get { return _totalFare; } set { _totalFare = value; RaisePropertyChanged(_totalFarePropertyName); } } .... private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>().Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>().Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>().Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   private void OnTaxiStarted(TaxiStarted taxiStarted) { Fares.Add(new EntryFare()); Fares.Add(new StateTaxFare(taxiStarted)); Fares.Add(new NightSurchargeFare(taxiStarted)); Fares.Add(new PeakHourWeekdayFare(taxiStarted));   SetTotalFare(Fares); }   private void SetTotalFare(IEnumerable<IFare> fares) { TotalFare = (_totalFare ?? 0) + TaxiFareHelper.GetTotalFare(fares); } ....   } }   TotalViewModel subscribes to events, TaxiStartedEvent and rest. When TaxiStartedEvent gets invoked it calls the OnTaxiStarted method which sets the total fare which includes entry fee, state tax, nightly surcharge, peak hour weekday fare.   Note that TotalViewModel derives from ObservableBase which implements the method RaisePropertyChanged which we are invoking in Set of TotalFare property, i.e, once we update the TotalFare property it raises an the event that  allows the TotalFare text box to fetch the new value through the data context. ViewModel is communicating with View through data context and it has no knowledge about View, helping in loose coupling of ViewModel and View.   I have attached the source code (.Net 4.0, Prism 4.0, VS 2010) , download and play with it and don’t forget to leave your comments.  

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  • New features of C# 4.0

    This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p =&gt; p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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  • Server cannot set status after HTTP headers have been sent IIS7.5

    - by marcinn
    Hi, Sometimes I get exception in my production environment: Process information Process ID: 3832 Process name: w3wp.exe Account name: NT AUTHORITY\NETWORK SERVICE Exception information Exception type: System.Web.HttpException Exception message: Server cannot set status after HTTP headers have been sent. Request information Request URL: http://www.myulr.pl/logon Request path: /logon User host address: 10.11.9.1 User: user001 Is authenticated: True Authentication Type: Forms Thread account name: NT AUTHORITY\NETWORK SERVICE Thread information Thread ID: 10 Thread account name: NT AUTHORITY\NETWORK SERVICE Is impersonating: False Stack trace: at System.Web.HttpResponse.set_StatusCode(Int32 value) at System.Web.HttpResponseWrapper.set_StatusCode(Int32 value) at System.Web.Mvc.HandleErrorAttribute.OnException(ExceptionContext filterContext) at System.Web.Mvc.ControllerActionInvoker.InvokeExceptionFilters(ControllerContext controllerContext, IList(1) filters, Exception exception) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.<BeginProcessRequest>b__4() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8(1).<BeginSynchronous>b__7(IAsyncResult _) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult(1).End() at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& ompletedSynchronously) I didn't noticed this error on my test environment what should I check? I am using ASP.NET MVC 2 (Release Candidate 2)

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  • How to get foreignSecurityPrincipal from group. using DirectorySearcher

    - by kain64b
    What I tested with 0 results: string queryForeignSecurityPrincipal = "(&(objectClass=foreignSecurityPrincipal)(memberof:1.2.840.113556.1.4.1941:={0})(uSNChanged>={1})(uSNChanged<={2}))"; sidsForeign = GetUsersSidsByQuery(groupName, string.Format(queryForeignSecurityPrincipal, groupPrincipal.DistinguishedName, 0, 0)); public IList<SecurityIdentifier> GetUsersSidsByQuery(string groupName, string query) { List<SecurityIdentifier> results = new List<SecurityIdentifier>(); try{ using (var context = new PrincipalContext(ContextType.Domain, DomainName, User, Password)) { using (var groupPrincipal = GroupPrincipal.FindByIdentity(context, IdentityType.SamAccountName, groupName)) { DirectoryEntry directoryEntry = (DirectoryEntry)groupPrincipal.GetUnderlyingObject(); do { directoryEntry = directoryEntry.Parent; } while (directoryEntry.SchemaClassName != "domainDNS"); DirectorySearcher searcher = new DirectorySearcher(directoryEntry){ SearchScope=System.DirectoryServices.SearchScope.Subtree, Filter=query, PageSize=10000, SizeLimit = 15000 }; searcher.PropertiesToLoad.Add("objectSid"); searcher.PropertiesToLoad.Add("distinguishedname"); using (SearchResultCollection result = searcher.FindAll()) { foreach (var obj in result) { if (obj != null) { var valueProp = ((SearchResult)obj).Properties["objectSid"]; foreach (var atributeValue in valueProp) { SecurityIdentifier value = (new SecurityIdentifier((byte[])atributeValue, 0)); results.Add(value); } } } } } } } catch (Exception e) { WriteSystemError(e); } return results; } I tested it on usual users with query: "(&(objectClass=user)(memberof:1.2.840.113556.1.4.1941:={0})(uSNChanged>={1})(uSNChanged<={2}))" and it is work, I test with objectClass=* ... nothing help... But If I call groupPrincipal.GetMembers,I get all foreing user account from group. BUT groupPrincipal.GetMembers HAS MEMORY LEAK. Any Idea how to fix my query????

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  • Silverlight WCF serialization DataContract(IsReference=true) problem

    - by Ciaran
    Hi, I'm have a Silverlight 3 UI that access WCF services which in turn access respositories that use NHibernate. To overcome some NHibernate lazy loading issues with WCF I'm using my own DataContract surrogate as described here: http://timvasil.com/blog14/post/2008/02/WCF-serialization-with-NHibernate.aspx. In here I'm setting preserveObjectReferences = true My model contains cycles (i.e. Customer with IList[Order]) When I retrieve an object from my service it works fine, however when I try and send that same object back to the wcf service I get the error: System.ServiceModel.CommunicationException was unhandled by user code Message=There was an error while trying to serialize parameter http://tempuri.org/:searchCriteria. The InnerException message was 'Object graph ...' contains cycles and cannot be serialized if references are not tracked. Consider using the DataContractAttribute with the IsReference property set to true.' So cyclical references are now a problem in Silverlight, so I try change my DataContract to be [DataContract(IsReference=true)] but now when I try to retrieve an object from my service I get the following exception: System.ExecutionEngineException was unhandled Message=Exception of type 'System.ExecutionEngineException' was thrown. InnerException: Any ideas?

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  • Entity Framework + AutoMapper ( Entity to DTO and DTO to Entity )

    - by vbobruisk
    Hello. i got some problems using EF with AutoMapper. =/ for example : i got 2 related entities ( Customers and Orders ) and theyr DTO classes : class CustomerDTO { public string CustomerID {get;set;} public string CustomerName {get;set;} public IList< OrderDTO Orders {get;set;} } class OrderDTO { public string OrderID {get;set;} public string OrderDetails {get;set;} public CustomerDTO Customers {get;set;} } //when mapping Entity to DTO the code works Customers cust = getCustomer(id); Mapper.CreateMap< Customers, CustomerDTO (); Mapper.CreateMap< Orders, OrderDTO (); CustomerDTO custDTO = Mapper.Map(cust); //but when i try to map back from DTO to Entity it fails with AutoMapperMappingException. Mapper.Reset(); Mapper.CreateMap< CustomerDTO , Customers (); Mapper.CreateMap< OrderDTO , Orders (); Customers customerModel = Mapper.Map< CustomerDTO ,Customers (custDTO); // exception is thrown here Am i doeing something wrong ? Thanks in Advance !

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  • Passing List of Strings or Array of strings into Unity Injection Constructor (Config-Based)

    - by miguel
    I cannot seem to get unity working when attempting to pass in an array of strings into a constructor parameter list, while using XML configuration. When I try the following: <typeConfig ...> <constructor ...> <param ... parameterType="System.String[]"> <array> <value.../> <value.../> </array> </param> </constructor> </typeConfig> for a c'tor which looks like this: void Foo(string[] inputParams_){ ... } It always fails in Unity's FindConstructor(...) method stating that it cannot find a c'tor mathcing the parameter type of String.String Does anyone know how to pass an array of stings successfully into this type of c'tor? If not, how can I do so with a list of strings, if the c'tor were to accept an IList? Thanks!

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  • how to map SubclassMap and HasManyToMany in Fluent NHibernate

    - by Davide Orazio Montersino
    Hi everyone. My problem is fluent nhibernate mapping a many to many relationship, they end up referencing a non existent Id. public UserMap() { Id(x => x.Id); Map(x => x.Name); Map(x => x.Password); Map(x => x.Confirmed); HasMany(x => x.Nodes).Cascade.SaveUpdate(); HasManyToMany<Node>(x => x.Events).Cascade.SaveUpdate().Table("RSVPs"); } public EventMap() { Map(x => x.Starts); Map(x => x.Ends); HasManyToMany<User>(x => x.Rsvps).Cascade.SaveUpdate().Table("RSVPs"); } public NodeMap() { Id(x => x.Id); Map(x => x.Title); Map(x => x.Body).CustomSqlType("text"); Map(x => x.CreationDate); References(x => x.Author).Cascade.SaveUpdate(); Map(x => x.Permalink).Unique().Not.Nullable(); } Those are my classes -notice that Event inherits from Node: public class Event : Node//, IEvent { private DateTime _starts = DateTime.MinValue; private DateTime _ends = DateTime.MaxValue; public virtual IList<User> Rsvps { get; set; } } The problem is, the generated RSVPs table is like that: Event_id User_id Node_id Of course the Event table has no ID - only a Node_id. When trying to save a relationship it will try to save a NULL event_id thus generating an error.

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  • nHibernate Mapping with Oracle Varchar2 Data Types

    - by Blake Blackwell
    I am new to nHibernate and having some issues getting over the learning curve. My current question involves passing a string value as a parameter to a stored sproc. The error I get is: Input string is not in correct format. My mapping file looks like this: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="MyCompany.MyProject.Core" namespace="MyCompany.MyProject.Core" > <class name="MyCompany.MyProject.Core.MyTable" table="My_Table" lazy="false"> <id name="Id" column="Id"></id> <property name="Name" column="Name" /> </class> <sql-query name="sp_GetTable" callable="true"> <query-param name="int_Id" type="int"/> <query-param name="vch_MyId" type="String"/> <return class="MyCompany.MyProject.Core.MyTable" /> call procedure MYPKG.MYPROC(:int_Id,:vch_MyId) </sql-query> </hibernate-mapping> When I debug nHibernate it looks like it is not an actual string value, but instead just an object value. Not sure about that though... EDIT: Adding additional code for clarification: UNIT Test List<ProcedureParameter> parms = new List<ProcedureParameter>(); parms.Add( new ProcedureParameter { ParamName = "int_Id", ParamValue = 1} ); parms.Add( new ProcedureParameter { ParamName = "vch_MyId", ParamValue = "{D18BED07-84AB-494F-A94F-6F894E284227}" } ); try { IList<MyTable> myTables = _context.GetAllByID<MyTable>( "sp_GetTable", parms ); Assert.AreNotEqual( 0, myTables.Count ); } catch( Exception ex ) { throw ex; } Data Context Method IQuery query = _session.GetNamedQuery( queryName ); foreach( ProcedureParameter parm in parms ) { query.SetParameter(parm.ParamName, "'" + parm.ParamValue + "'"); } return query.List<T>(); Come to think of it, it may have something to do with my DataContext method.

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  • How can I write a clean Repository without exposing IQueryable to the rest of my application?

    - by Simucal
    So, I've read all the Q&A's here on SO regarding the subject of whether or not to expose IQueryable to the rest of your project or not (see here, and here), and I've ultimately decided that I don't want to expose IQueryable to anything but my Model. Because IQueryable is tied to certain persistence implementations I don't like the idea of locking myself into this. Similarly, I'm not sure how good I feel about classes further down the call chain modifying the actual query that aren't in the repository. So, does anyone have any suggestions for how to write a clean and concise Repository without doing this? One problem I see, is my Repository will blow up from a ton of methods for various things I need to filter my query off of. Having a bunch of: IEnumerable GetProductsSinceDate(DateTime date); IEnumberable GetProductsByName(string name); IEnumberable GetProductsByID(int ID); If I was allowing IQueryable to be passed around I could easily have a generic repository that looked like: public interface IRepository<T> where T : class { T GetById(int id); IQueryable<T> GetAll(); void InsertOnSubmit(T entity); void DeleteOnSubmit(T entity); void SubmitChanges(); } However, if you aren't using IQueryable then methods like GetAll() aren't really practical since lazy evaluation won't be taking place down the line. I don't want to return 10,000 records only to use 10 of them later. What is the answer here? In Conery's MVC Storefront he created another layer called the "Service" layer which received IQueryable results from the respository and was responsible for applying various filters. Is this what I should do, or something similar? Have my repository return IQueryable but restrict access to it by hiding it behind a bunch of filter classes like GetProductByName, which will return a concrete type like IList or IEnumerable?

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  • LINQ self referencing query

    - by Chris
    I have the following SQL query: select p1.[id], p1.[useraccountid], p1.[subject], p1.[message], p1.[views], p1.[parentid], case when p2.[created] is null then p1.[created] else p2.[created] end as LastUpdate from forumposts p1 left join ( select parentid, max(created) as [created] from forumposts group by parentid ) p2 on p2.parentid = p1.id where p1.[parentid] is null order by LastUpdate desc Using the following class: public class ForumPost : PersistedObject { public int Views { get; set; } public string Message { get; set; } public string Subject { get; set; } public ForumPost Parent { get; set; } public UserAccount UserAccount { get; set; } public IList<ForumPost> Replies { get; set; } } How would I replicate such a query in LINQ? I've tried several variations, but I seem unable to get the correct join syntax. Is this simply a case of a query that is too complicated for LINQ? Can it be done using nested queries some how? The purpose of the query is to find the most recently updated posts i.e. replying to a post would bump it to the top of the list. Replies are defined by the ParentID column, which is self-referencing.

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  • Predicate problem in ToSelectList

    - by Stefanvds
    the ToSelectList method I have: public static IList<SelectListItem> ToSelectList<T>(this IEnumerable<T> itemsToMap, Func<T, string> textProperty, Func<T, string> valueProperty, Predicate<T> isSelected) { var result = new List<SelectListItem>(); foreach (var item in itemsToMap) { result.Add(new SelectListItem { Value = valueProperty(item), Text = textProperty(item), Selected = isSelected(item) }); } return result; } when I call this method here: public static List<SelectListItem> lesgeverList(int selectedID) { NASDataContext _db = new NASDataContext(); var lesg = (from l in _db.Lesgevers where l.LG_Naam != "leeg" orderby l.LG_Naam select l).ToSelectList(m => m.LG_Naam + " " + m.LG_Vnaam, m => m.LG_ID.ToString(), m => m.LG_ID == selectedID); return lesg.ToList(); } the selectlist I get has the selectedID as selected. now, when I want to have multiple selected items, I give a list of Lesgevers public static List<SelectListItem> lesgeverList(List<Lesgever> lg) { NASDataContext _db = new NASDataContext(); var test = (from l in _db.Lesgevers where l.LG_Naam != "leeg" && lg.Contains(l) orderby l.LG_Naam, l.LG_Vnaam select l).ToList(); var lesg = (from l in _db.Lesgevers where l.LG_Naam != "leeg" orderby l.LG_Naam, l.LG_Vnaam select l).ToSelectList(m => m.LG_Naam + " " + m.LG_Vnaam, m => m.LG_ID.ToString(), m => lg.Contains(m)); return lesg.ToList(); } the var test does return the Lesgevers that i have in the lg List, in my 'var lesg', there are no selectlistitem's selected at all. where is my mistake? :) how do I fix thix?

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  • NHibernate save / update event listeners: listening for child object saves

    - by James Allen
    I have an Area object which has many SubArea children: public class Area { ... public virtual IList<SubArea> SubAreas { get; set; } } he children are mapped as a uni-directional non-inverse relationship: public class AreaMapping : ClassMap<Area> { public AreaMapping() { HasMany(x => x. SubAreas).Not.Inverse().Cascade.AllDeleteOrphan(); } } The Area is my aggregate root. When I save an area (e.g. Session.Save(area) ), the area gets saved and the child SubAreas automatically cascaded. I want to add a save or update event listener to catch whenever my areas and/or subareas are persisted. Say for example I have an area, which has 5 SubAreas. If I hook into SaveEventListeners: Configuration.EventListeners.SaveEventListeners = new ISaveOrUpdateEventListener[] { mylistener }; When I save the area, Mylistener is only fired once only for area (SubAreas are ignored). I want the 5 SubAreas to be caught aswell in the event listener. If I hook into SaveOrUpdateEventListeners instead: Configuration.EventListeners.SaveOrUpdateEventListeners = new ISaveOrUpdateEventListener[] { mylistener }; When I save the area, Mylistener is not fired at all. Strangely, if I hook into SaveEventListeners and SaveOrUpdateEventListeners: Configuration.EventListeners.SaveEventListeners = new ISaveOrUpdateEventListener[] { mylistener }; Configuration.EventListeners.SaveOrUpdateEventListeners = new ISaveOrUpdateEventListener[] { mylistener }; When I save the area, Mylistener is fired 11 times: once for the area, and twice for each SubArea! (I think because NHIbernate is INSERTing the SubArea and then UPDATING with the area foreign key). Does anyone know what I'm doing wrong here, and how I can get the listener to fire once for each area and subarea?

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