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  • Get Application Title from Windows Phone

    - by psheriff
    In a Windows Phone application that I am currently developing I needed to be able to retrieve the Application Title of the phone application. You can set the Deployment Title in the Properties of your Windows Phone Application, however getting to this value programmatically can be a little tricky. This article assumes that you have Visual Studio 2010 and the Windows Phone tools installed along with it. The Windows Phone tools must be downloaded separately and installed with Visual Studio2010. You may also download the free Visual Studio2010 Express for Windows Phone developer environment. The WMAppManifest.xml File First off you need to understand that when you set the Deployment Title in the Properties windows of your Windows Phone application, this title actually gets stored into an XML file located under the \Properties folder of your application. This XML file is named WMAppManifest.xml. A portion of this file is shown in the following listing. <?xml version="1.0" encoding="utf-8"?><Deployment  http://schemas.microsoft.com/windowsphone/2009/deployment"http://schemas.microsoft.com/windowsphone/2009/deployment"  AppPlatformVersion="7.0">  <App xmlns=""       ProductID="{71d20842-9acc-4f2f-b0e0-8ef79842ea53}"       Title="Mobile Time Track"       RuntimeType="Silverlight"       Version="1.0.0.0"       Genre="apps.normal"       Author="PDSA, Inc."       Description="Mobile Time Track"       Publisher="PDSA, Inc."> ... ...  </App></Deployment> Notice the “Title” attribute in the <App> element in the above XML document. This is the value that gets set when you modify the Deployment Title in your Properties Window of your Phone project. The only value you can set from the Properties Window is the Title. All of the other attributes you see here must be set by going into the XML file and modifying them directly. Note that this information duplicates some of the information that you can also set from the Assembly Information… button in the Properties Window. Why Microsoft did not just use that information, I don’t know. Reading Attributes from WMAppManifest I searched all over the namespaces and classes within the Windows Phone DLLs and could not find a way to read the attributes within the <App> element. Thus, I had to resort to good old fashioned XML processing. First off I created a WinPhoneCommon class and added two static methods as shown in the snippet below: public class WinPhoneCommon{  /// <summary>  /// Returns the Application Title   /// from the WMAppManifest.xml file  /// </summary>  /// <returns>The application title</returns>  public static string GetApplicationTitle()  {    return GetWinPhoneAttribute("Title");  }   /// <summary>  /// Returns the Application Description   /// from the WMAppManifest.xml file  /// </summary>  /// <returns>The application description</returns>  public static string GetApplicationDescription()  {    return GetWinPhoneAttribute("Description");  }   ... GetWinPhoneAttribute method here ...} In your Windows Phone application you can now simply call WinPhoneCommon.GetApplicationTitle() or WinPhone.GetApplicationDescription() to retrieve the Title or Description properties from the WMAppManifest.xml file respectively. You notice that each of these methods makes a call to the GetWinPhoneAttribute method. This method is shown in the following code snippet: /// <summary>/// Gets an attribute from the Windows Phone WMAppManifest.xml file/// To use this method, add a reference to the System.Xml.Linq DLL/// </summary>/// <param name="attributeName">The attribute to read</param>/// <returns>The Attribute's Value</returns>private static string GetWinPhoneAttribute(string attributeName){  string ret = string.Empty;   try  {    XElement xe = XElement.Load("WMAppManifest.xml");    var attr = (from manifest in xe.Descendants("App")                select manifest).SingleOrDefault();    if (attr != null)      ret = attr.Attribute(attributeName).Value;  }  catch  {    // Ignore errors in case this method is called    // from design time in VS.NET  }   return ret;} I love using the new LINQ to XML classes contained in the System.Xml.Linq.dll. When I did a Bing search the only samples I found for reading attribute information from WMAppManifest.xml used either an XmlReader or XmlReaderSettings objects. These are fine and work, but involve a little extra code. Instead of using these, I added a reference to the System.Xml.Linq.dll, then added two using statements to the top of the WinPhoneCommon class: using System.Linq;using System.Xml.Linq; Now, with just a few lines of LINQ to XML code you can read to the App element and extract the appropriate attribute that you pass into the GetWinPhoneAttribute method. Notice that I added a little bit of exception handling code in this method. I ignore the exception in case you call this method in the Loaded event of a user control. In design-time you cannot access the WMAppManifest file and thus an exception would be thrown. Summary In this article you learned how to retrieve the attributes from the WMAppManifest.xml file. I use this technique to grab information that I would otherwise have to hard-code in my application. Getting the Title or Description for your Windows Phone application is easy with just a little bit of LINQ to XML code. NOTE: You can download the complete sample code at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "Get Application Title from Windows Phone" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free video on Silverlight entitled Silverlight XAML for the Complete Novice - Part 1.  

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  • I'm getting this exception : Unresolved compilation problems

    - by Stephan
    I get this exception after i removed from my project the jars (pdfbox ,bouncycastle etc) and moved them to another folder but i included them in the build path ... at the first line eclipse shows this error( the constructor PDFParser(InputStream) refers to missing type InputStream) -altought FileInputStream is extended from InputStream- and i don't know why? FileInputStream in = new FileInputStream(path); PDFParser parser = new PDFParser(in); PDFTextStripper textStripper = new PDFTextStripper(); parser.parse(); String text = textStripper.getText(new PDDocument(parser.getDocument())); any ideas? ** Exception in thread "AWT-EventQueue-0" java.lang.Error: Unresolved compilation problems: The constructor PDFParser(InputStream) refers to the missing type InputStream The constructor PDFTextStripper() refers to the missing type IOException The method parse() from the type PDFParser refers to the missing type IOException The method getText(PDDocument) from the type PDFTextStripper refers to the missing type IOException The method getDocument() from the type PDFParser refers to the missing type IOException The method getDocument() from the type PDFParser refers to the missing type IOException The method close() from the type COSDocument refers to the missing type IOException **

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  • How to return a dynamic value from a Mocha mock in Ruby

    - by Vivek
    The gist of my problem is as follows:- I'm writing a Mocha mock in Ruby for the method represented as "post_to_embassy" below. It is not really our concern, for the purpose of describing the problem, what the actual method does. But I need the mock to return a dynamic value. The proc '&prc' below is executing rightly in place of the actual method. But the "with" method in Mocha only allows for boolean values to be returned. So the code below outputs nil. I need it to output the value being passed through orderInfoXml. Does anyone know of an alternate method I can use? require 'rubygems' require 'mocha' include Mocha::API class EmbassyInterface def post_to_embassy(xml) puts "This is from the original class:-" puts xml return xml end end orderInfoXml = "I am THE XML" mock = EmbassyInterface.new prc = Proc.new do |orderXml| puts "This is from the mocked proc:-" puts orderXml orderXml end mock.stubs(:post_to_embassy).with(&prc) mock_result = mock.post_to_embassy(orderInfoXml) p mock_result #p prc.call("asd") output:- This is from the mocked proc:- I am THE XML nil

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  • Merge Records in Session bean by using ADF Drag/Drop

    - by shantala.sankeshwar
    This article describes how to merge multiple selected records in Session Bean using ADF drag & drop feature. Below described is simple use case that shows how exactly this can be achieved. Here we will have table & user input field.Table shows  EMP records & user input field accepts Salary.When we drag & drop multiple records on user input field,the selected records get updated with the new Salary provided. Steps: Let us suppose that we have created Java EE Web Application with Entities from Emp table.Then create EJB Session Bean & generate Data control for the same. Write a simple code in sessionEJBBean & expose this method to local interface :  public void updateEmprecords(List empList, Object sal) {       Emp emp = null;       for (int i = 0; i < empList.size(); i++)       {        emp = em.find(Emp.class, empList.get(i));         emp.setSal((BigDecimal)sal);       }      em.merge(emp);   } Now let us create updateEmpRecords.jspx page in viewController project & Drop empFindAll object as ADF Table Define custom SelectionListener method for the table :   public void selectionListener(SelectionEvent selectionEvent)     {     // This method gets the Empno of the selected record & stores in the list object      UIXTable table = (UIXTable)selectionEvent.getComponent();      FacesCtrlHierNodeBinding fcr      =(FacesCtrlHierNodeBinding)table.getSelectedRowData();      Number empNo = (Number)fcr.getAttribute("empno") ;      this.getSelectedRowsList().add(empNo);     }Set table's selectedRowKeys to #{bindings.empFindAll.collectionModel.selectedRow}"Drop inputText on the same jspx page that accepts Salary .Now we would like to drag records from the above table & drop that on the inputtext field.This feature can be achieved by inserting dragSource operation inside the table & dropTraget operation inside the inputText:<af:dragSource discriminant="tab"/> //Insert this inside the table<af:inputText label="Enter Salary" id="it13" autoSubmit="true"       binding="# {test.deptValue}">       <af:dropTarget dropListener="#{test.handleTableDrop}">       <af:dataFlavor        flavorClass="org.apache.myfaces.trinidad.model.RowKeySet"    discriminant="tab"/>       </af:dropTarget>       <af:convertNumber/> </af:inputText> In the above code when the user drags & drops multiple records on inputText,the dropListener method gets called.Goto the respective page definition file & create updateEmprecords method action& execute action dropListener method code:        public DnDAction handleTableDrop(DropEvent dropEvent)        {          //Below code gets the updateEmprecords method,passes parameters & executes method            DataFlavor<RowKeySet> df = DataFlavor.getDataFlavor(RowKeySet.class);            RowKeySet droppedKeySet = dropEvent.getTransferable().getData(df);            if (droppedKeySet != null && droppedKeySet.size() > 0)           {                  DCBindingContainer bindings =                  (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry();                  OperationBinding updateEmp;                  updateEmp= bindings.getOperationBinding("updateEmprecords");                  updateEmp.getParamsMap().put("sal",                  this.getDeptValue().getAttributes().get("value"));                            updateEmp.getParamsMap().put("empList", this.getSelectedRowsList());                  updateEmp.execute(); //Below code performs execute operation to refresh the updated records                 OperationBinding executeBinding;                 executeBinding= bindings.getOperationBinding("Execute");                 executeBinding.execute(); AdfFacesContext.getCurrentInstance().addPartialTarget(dropEvent.getDragComponent());                this.getSelectedRowsList().clear();          }                 return DnDAction.NONE;        }Run updateEmpRecords.jspx page & enter any Salary say '5000'.Select multiple records in table & drop these selected records on the inputText Salary. Note that all the selected records salary value gets updated to 5000.Technorati Tags: ADF Drag and drop,EJB Session bean,ADF table,inputText,DropEvent  

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  • Fun With the Chrome JavaScript Console and the Pluralsight Website

    - by Steve Michelotti
    Originally posted on: http://geekswithblogs.net/michelotti/archive/2013/07/24/fun-with-the-chrome-javascript-console-and-the-pluralsight-website.aspxI’m currently working on my third course for Pluralsight. Everyone already knows that Scott Allen is a “dominating force” for Pluralsight but I was curious how many courses other authors have published as well. The Pluralsight Authors page - http://pluralsight.com/training/Authors – shows all 146 authors and you can click on any author’s page to see how many (and which) courses they have authored. The problem is: I don’t want to have to click into 146 pages to get a count for each author. With this in mind, I figured I could write a little JavaScript using the Chrome JavaScript console to do some “detective work.” My first step was to figure out how the HTML was structured on this page so I could do some screen-scraping. Right-click the first author - “Inspect Element”. I can see there is a primary <div> with a class of “main” which contains all the authors. Each author is in an <h3> with an <a> tag containing their name and link to their page:     This web page already has jQuery loaded so I can use $ directly from the console. This allows me to just use jQuery to inspect items on the current page. Notice this is a multi-line command. In order to use multiple lines in the console you have to press SHIFT-ENTER to go to the next line:     Now I can see I’m extracting data just fine. At this point I want to follow each URL. Then I want to screen-scrape this next page to see how many courses each author has done. Let’s take a look at the author detail page:       I can see we have a table (with a css class of “course”) that contains rows for each course authored. This means I can get the number of courses pretty easily like this:     Now I can put this all together. Back on the authors page, I want to follow each URL, extract the returned HTML, and grab the count. In the code below, I simply use the jQuery $.get() method to get the author detail page and the “data” variable that is in the callback contains the HTML. A nice feature of jQuery is that I can simply put this HTML string inside of $() and I can use jQuery selectors directly on it in conjunction with the find() method:     Now I’m getting somewhere. I have every Pluralsight author and how many courses each one has authored. But that’s not quite what I’m after – what I want to see are the authors that have the MOST courses in the library. What I’d like to do is to put all of the data in an array and then sort that array descending by number of courses. I can add an item to the array after each author detail page is returned but the catch here is that I can’t perform the sort operation until ALL of the author detail pages have executed. The jQuery $.get() method is naturally an async method so I essentially have 146 async calls and I don’t want to perform my sort action until ALL have completed (side note: don’t run this script too many times or the Pluralsight servers might think your an evil hacker attempting a DoS attack and deny you). My C# brain wants to use a WaitHandle WaitAll() method here but this is JavaScript. I was able to do this by using the jQuery Deferred() object. I create a new deferred object for each request and push it onto a deferred array. After each request is complete, I signal completion by calling the resolve() method. Finally, I use a $.when.apply() method to execute my descending sort operation once all requests are complete. Here is my complete console command: 1: var authorList = [], 2: defList = []; 3: $(".main h3 a").each(function() { 4: var def = $.Deferred(); 5: defList.push(def); 6: var authorName = $(this).text(); 7: var authorUrl = $(this).attr('href'); 8: $.get(authorUrl, function(data) { 9: var courseCount = $(data).find("table.course tbody tr").length; 10: authorList.push({ name: authorName, numberOfCourses: courseCount }); 11: def.resolve(); 12: }); 13: }); 14: $.when.apply($, defList).then(function() { 15: console.log("*Everything* is complete"); 16: var sortedList = authorList.sort(function(obj1, obj2) { 17: return obj2.numberOfCourses - obj1.numberOfCourses; 18: }); 19: for (var i = 0; i < sortedList.length; i++) { 20: console.log(authorList[i]); 21: } 22: });   And here are the results:     WOW! John Sonmez has 44 courses!! And Matt Milner has 29! I guess Scott Allen isn’t the only “dominating force”. I would have assumed Scott Allen was #1 but he comes in as #3 in total course count (of course Scott has 11 courses in the Top 50, and 14 in the Top 100 which is incredible!). Given that I’m in the middle of producing only my third course, I better get to work!

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  • Perl equivalent to Java's "throws" clause

    - by Konerak
    Is there a way in Perl to declare that a method can throw an error (or die)? EDIT: What interests me the most is a way to get the compiler or IDE to tell me I have an unchecked exception somewhere in my code. I always loved how in Java, a method could handle an Exception and/or throw it. The method signature allows to put "throws MyException", so a good IDE/compiler would know that if you use said method somewhere in your code, you'd have to check for the Exception or declare your function to "throws" the Exception further. I'm unable to find something alike in Perl. A collegue of mine wrote a method which "dies" on incorrect input, but I forget to eval-if($@) it... offcourse the error was only discovered while a user was running the application. (offcourse I doubt if there is any existing IDE that could find these kind of things for Perl, but atleast perl -cw should be able to, no?)

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  • Like Html.RenderAction() but without reinstantiating the controller object

    - by Jørn Schou-Rode
    I like to use the RenderAction extension method on the HtmlHelper object to render sidebars and the like in pages, as it allows me to keep the data access code for each such part in separate methods on the controller. Using an abstract controller base, I can define a default "sidebar strategy", which can then be refined by overriding the method in a concrete controller, when needed. The only "problem" I have with this approach, is that the RenderAction is built in a way where it always creates a news instance of the controller class, even when rendering actions from the controller already in action. Some of my controllers does some data lookup in their Initialize method, and using the RenderAction method in the view causes this to occur several times in the same request. Is there some alternative to RenderAction which will reuse the controller object if the action method to be invoked is on the same controller class as the "parent" action?

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  • Can the Perl compiler tell me if I have an unchecked exception in my code?

    - by Konerak
    Is there a way in Perl to declare that a method can throw an error (or die)? EDIT: What interests me the most is a way to get the compiler or IDE to tell me I have an unchecked exception somewhere in my code. I always loved how in Java, a method could handle an Exception and/or throw it. The method signature allows to put "throws MyException", so a good IDE/compiler would know that if you use said method somewhere in your code, you'd have to check for the Exception or declare your function to "throws" the Exception further. I'm unable to find something alike in Perl. A collegue of mine wrote a method which "dies" on incorrect input, but I forget to eval-if($@) it... offcourse the error was only discovered while a user was running the application. (offcourse I doubt if there is any existing IDE that could find these kind of things for Perl, but atleast perl -cw should be able to, no?)

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  • Another ArrayIndexOutOfBoundsException in ListView

    - by synic
    This one is different than the other one I posted. Any ideas? java.lang.IndexOutOfBoundsException: Invalid location 14, size is 1 at java.util.ArrayList.get(ArrayList.java:341) at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:188) at android.widget.AbsListView.obtainView(AbsListView.java:1256) at android.widget.ListView.makeAndAddView(ListView.java:1668) at android.widget.ListView.fillUp(ListView.java:667) at android.widget.ListView.fillGap(ListView.java:613) at android.widget.AbsListView.trackMotionScroll(AbsListView.java:2531) at android.widget.AbsListView$FlingRunnable.run(AbsListView.java:2353) at android.os.Handler.handleCallback(Handler.java:587) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:123) at android.app.ActivityThread.main(ActivityThread.java:4595) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:521) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) at dalvik.system.NativeStart.main(Native Method)

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  • How to get a handle/reference to the current controller object inside a rails functional test?

    - by Dave Paroulek
    I must be missing something very simple, but can't find the answer to this. I have a method named foo inside bar_controller. I simply want to call that method from inside a functional test. Here's my controller: class BarsController < ApplicationController def foo # does stuff end end Here's my functional test: class BarsControllerTest << ActionController::TestCase def "test foo" do # run foo foo # assert stuff end end When I run the test I get: NameError: undefined local variable or method `foo' for #<BarsControllerTest:0x102f2eab0> All the documentation on functional tests describe how to simulate a http get request to the bar_controller which then runs the method. But I'd just like to run the method without hitting it with an http get or post request. Is that possible? There must be a reference to the controller object inside the functional test, but I'm still learning ruby and rails so need some help.

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  • Using Delegates in C# (Part 1)

    - by rajbk
    This post provides a very basic introduction of delegates in C#. Part 2 of this post can be read here. A delegate is a class that is derived from System.Delegate.  It contains a list of one or more methods called an invocation list. When a delegate instance is “invoked” with the arguments as defined in the signature of the delegate, each of the methods in the invocation list gets invoked with the arguments. The code below shows example with static and instance methods respectively: Static Methods 1: using System; 2: using System.Linq; 3: using System.Collections.Generic; 4: 5: public delegate void SayName(string name); 6: 7: public class Program 8: { 9: [STAThread] 10: static void Main(string[] args) 11: { 12: SayName englishDelegate = new SayName(SayNameInEnglish); 13: SayName frenchDelegate = new SayName(SayNameInFrench); 14: SayName combinedDelegate =(SayName)Delegate.Combine(englishDelegate, frenchDelegate); 15: 16: combinedDelegate.Invoke("Tom"); 17: Console.ReadLine(); 18: } 19: 20: static void SayNameInFrench(string name) { 21: Console.WriteLine("J'ai m'appelle " + name); 22: } 23: 24: static void SayNameInEnglish(string name) { 25: Console.WriteLine("My name is " + name); 26: } 27: } We have declared a delegate of type SayName with return type of void and taking an input parameter of name of type string. On line 12, we create a new instance of this delegate which refers to a static method - SayNameInEnglish.  SayNameInEnglish has the same return type and parameter list as the delegate declaration.  Once a delegate is instantiated, the instance will always refer to the same target. Delegates are immutable. On line 13, we create a new instance of the delegate but point to a different static method. As you may recall, a delegate instance encapsulates an invocation list. You create an invocation list by combining delegates using the Delegate.Combine method (there is an easier syntax as you will see later). When two non null delegate instances are combined, their invocation lists get combined to form a new invocation list. This is done in line 14.  On line 16, we invoke the delegate with the Invoke method and pass in the required string parameter. Since the delegate has an invocation list with two entries, each of the method in the invocation list is invoked. If an unhandled exception occurs during the invocation of one of these methods, the exception gets bubbled up to the line where the invocation was made (line 16). If a delegate is null and you try to invoke it, you will get a System.NullReferenceException. We see the following output when the method is run: My name is TomJ'ai m'apelle Tom Instance Methods The code below outputs the same results as before. The only difference here is we are creating delegates that point to a target object (an instance of Translator) and instance methods which have the same signature as the delegate type. The target object can never be null. We also use the short cut syntax += to combine the delegates instead of Delegate.Combine. 1: public delegate void SayName(string name); 2: 3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Translator translator = new Translator(); 9: SayName combinedDelegate = new SayName(translator.SayNameInEnglish); 10: combinedDelegate += new SayName(translator.SayNameInFrench); 11:  12: combinedDelegate.Invoke("Tom"); 13: Console.ReadLine(); 14: } 15: } 16: 17: public class Translator { 18: public void SayNameInFrench(string name) { 19: Console.WriteLine("J'ai m'appelle " + name); 20: } 21: 22: public void SayNameInEnglish(string name) { 23: Console.WriteLine("My name is " + name); 24: } 25: } A delegate can be removed from a combination of delegates by using the –= operator. Removing a delegate from an empty list or removing a delegate that does not exist in a non empty list will not result in an exception. Delegates are invoked synchronously using the Invoke method. We can also invoke them asynchronously using the BeginInvoke and EndInvoke methods which are compiler generated.

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  • Lazy loading of child throwing session error

    - by Thomas Buckley
    I'm the following error when calling purchaseService.updatePurchase(purchase) inside my TagController: SEVERE: Servlet.service() for servlet [PurchaseAPIServer] in context with path [/PurchaseAPIServer] threw exception [Request processing failed; nested exception is org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.app.model.Purchase.tags, no session or session was closed] with root cause org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.app.model.Purchase.tags, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368) at org.hibernate.collection.PersistentSet.add(PersistentSet.java:212) at com.app.model.Purchase.addTags(Purchase.java:207) at com.app.controller.TagController.createAll(TagController.java:79) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:212) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) TagController: @RequestMapping(value = "purchases/{purchaseId}/tags", method = RequestMethod.POST, params = "manyTags") @ResponseStatus(HttpStatus.CREATED) public void createAll(@PathVariable("purchaseId") final Long purchaseId, @RequestBody final Tag[] entities) { Purchase purchase = purchaseService.getById(purchaseId); Set<Tag> tags = new HashSet<Tag>(Arrays.asList(entities)); purchase.addTags(tags); purchaseService.updatePurchase(purchase); } Purchase: @Entity @XmlRootElement public class Purchase implements Serializable { /** * */ private static final long serialVersionUID = 6603477834338392140L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @OneToMany(mappedBy = "purchase", fetch = FetchType.LAZY, cascade={CascadeType.ALL}) private Set<Tag> tags; @JsonIgnore public Set<Tag> getTags() { if (tags == null) { tags = new LinkedHashSet<Tag>(); } return tags; } public void setTags(Set<Tag> tags) { this.tags = tags; } ... } Tag: @Entity @XmlRootElement public class Tag implements Serializable { /** * */ private static final long serialVersionUID = 5165922776051697002L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(fetch = FetchType.LAZY) @JoinColumns({@JoinColumn(name = "PURCHASEID", referencedColumnName = "ID")}) private Purchase purchase; @JsonIgnore public Purchase getPurchase() { return purchase; } public void setPurchase(Purchase purchase) { this.purchase = purchase; } } PurchaseService: @Service public class PurchaseService implements IPurchaseService { @Autowired private IPurchaseDAO purchaseDAO; public PurchaseService() { } @Transactional public List<Purchase> getAll() { return purchaseDAO.findAll(); } @Transactional public Purchase getById(Long id) { return purchaseDAO.findOne(id); } @Transactional public void addPurchase(Purchase purchase) { purchaseDAO.save(purchase); } @Transactional public void updatePurchase(Purchase purchase) { purchaseDAO.update(purchase); } } TagService: @Service public class TagService implements ITagService { @Autowired private ITagDAO tagDAO; public TagService() { } @Transactional public List<Tag> getAll() { return tagDAO.findAll(); } @Transactional public Tag getById(Long id) { return tagDAO.findOne(id); } @Transactional public void addTag(Tag tag) { tagDAO.save(tag); } @Transactional public void updateTag(Tag tag) { tagDAO.update(tag); } } Any ideas on how I can fix this? (I want to avoid using EAGER loading). Do I need to setup some form of session management for transactions? Thanks

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  • Calling Facebook API without authenticating user/"connecting"

    - by Andy
    Hi, I am working with facebook's API and I want to call the links.prevew method. http://wiki.developers.facebook.com/index.php/Links.preview Is it possible to call this method without having my user authenticate or "connect"? For example, not all of my users have hooked up their facebook accounts to my website, but I still want to use this API method. I am getting the following error: Fatal error: Uncaught Exception: 453: A session key is required for calling this method thrown in /public_html/libs/facebook.php on line 413 But on the wiki it says that the method does not require a session key? If it is not possible to make API calls without such a key, is there anyway I can make calls on behalf of my account or my applications account (rather then a users account)? Any help is appreciated, thanks!

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  • Checking who is connected to your server, with PowerShell.

    - by Fatherjack
    There are many occasions when, as a DBA, you want to see who is connected to your SQL Server, along with how they are connecting and what sort of activities they are carrying out. I’m going to look at a couple of ways of getting this information and compare the effort required and the results achieved of each. SQL Server comes with a couple of stored procedures to help with this sort of task – sp_who and its undocumented counterpart sp_who2. There is also the pumped up version of these called sp_whoisactive, written by Adam Machanic which does way more than these procedures. I wholly recommend you try it out if you don’t already know how it works. When it comes to serious interrogation of your SQL Server activity then it is absolutely indispensable. Anyway, back to the point of this blog, we are going to look at getting the information from sp_who2 for a remote server. I wrote this Powershell script a week or so ago and was quietly happy with it for a while. I’m relatively new to Powershell so forgive both my rather low threshold for entertainment and the fact that something so simple is a moderate achievement for me. $Server = 'SERVERNAME' $SMOServer = New-Object Microsoft.SQLServer.Management.SMO.Server $Server # connection and query stuff         $ConnectionStr = "Server=$Server;Database=Master;Integrated Security=True" $Query = "EXEC sp_who2" $Connection = new-object system.Data.SQLClient.SQLConnection $Table = new-object "System.Data.DataTable" $Connection.connectionstring = $ConnectionStr try{ $Connection.open() $Command = $Connection.CreateCommand() $Command.commandtext = $Query $result = $Command.ExecuteReader() $Table.Load($result) } catch{ # Show error $error[0] | format-list -Force } $Title = "Data access processes (" + $Table.Rows.Count + ")" $Table | Out-GridView -Title $Title $Connection.close() So this is pretty straightforward, create an SMO object that represents our chosen server, define a connection to the database and a table object for the results when we get them, execute our query over the connection, load the results into our table object and then, if everything is error free display these results to the PowerShell grid viewer. The query simply gets the results of ‘EXEC sp_who2′ for us. Depending on how many connections there are will influence how long the query runs. The grid viewer lets me sort and search the results so it can be a pretty handy way to locate troublesome connections. Like I say, I was quite pleased with this, it seems a pretty simple script and was working well for me, I have added a few parameters to control the output and give me more specific details but then I see a script that uses the $SMOServer object itself to provide the process information and saves having to define the connection object and query specifications. $Server = 'SERVERNAME' $SMOServer = New-Object Microsoft.SQLServer.Management.SMO.Server $Server $Processes = $SMOServer.EnumProcesses() $Title = "SMO processes (" + $Processes.Rows.Count + ")" $Processes | Out-GridView -Title $Title Create the SMO object of our server and then call the EnumProcesses method to get all the process information from the server. Staggeringly simple! The results are a little different though. Some columns are the same and we can see the same basic information so my first thought was to which runs faster – so that I can get my results more quickly and also so that I place less stress on my server(s). PowerShell comes with a great way of testing this – the Measure-Command function. All you have to do is wrap your piece of code in Measure-Command {[your code here]} and it will spit out the time taken to execute the code. So, I placed both of the above methods of getting SQL Server process connections in two Measure-Command wrappers and pressed F5! The Powershell console goes blank for a while as the code is executed internally when Measure-Command is used but the grid viewer windows appear and the console shows this. You can take the output from Measure-Command and format it for easier reading but in a simple comparison like this we can simply cross refer the TotalMilliseconds values from the two result sets to see how the two methods performed. The query execution method (running EXEC sp_who2 ) is the first set of timings and the SMO EnumProcesses is the second. I have run these on a variety of servers and while the results vary from execution to execution I have never seen the SMO version slower than the other. The difference has varied and the time for both has ranged from sub-second as we see above to almost 5 seconds on other systems. This difference, I would suggest is partly due to the cost overhead of having to construct the data connection and so on where as the SMO EnumProcesses method has the connection to the server already in place and just needs to call back the process information. There is also the difference in the data sets to consider. Let’s take a look at what we get and where the two methods differ Query execution method (sp_who2) SMO EnumProcesses Description - Urn What looks like an XML or JSON representation of the server name and the process ID SPID Spid The process ID Status Status The status of the process Login Login The login name of the user executing the command HostName Host The name of the computer where the  process originated BlkBy BlockingSpid The SPID of a process that is blocking this one DBName Database The database that this process is connected to Command Command The type of command that is executing CPUTime Cpu The CPU activity related to this process DiskIO - The Disk IO activity related to this process LastBatch - The time the last batch was executed from this process. ProgramName Program The application that is facilitating the process connection to the SQL Server. SPID1 - In my experience this is always the same value as SPID. REQUESTID - In my experience this is always 0 - Name In my experience this is always the same value as SPID and so could be seen as analogous to SPID1 from sp_who2 - MemUsage An indication of the memory used by this process but I don’t know what it is measured in (bytes, Kb, Mb…) - IsSystem True or False depending on whether the process is internal to the SQL Server instance or has been created by an external connection requesting data. - ExecutionContextID In my experience this is always 0 so could be analogous to REQUESTID from sp_who2. Please note, these are my own very brief descriptions of these columns, detail can be found from MSDN for columns in the sp_who results here http://msdn.microsoft.com/en-GB/library/ms174313.aspx. Where the columns are common then I would use that description, in other cases then the information returned is purely for interpretation by the reader. Rather annoyingly both result sets have useful information that the other doesn’t. sp_who2 returns Disk IO and LastBatch information which is really useful but the SMO processes method give you IsSystem and MemUsage which have their place in fault diagnosis methods too. So which is better? On reflection I think I prefer to use the sp_who2 method primarily but knowing that the SMO Enumprocesses method is there when I need it is really useful and I’m sure I’ll use it regularly. I’m OK with the fact that it is the slower method because Measure-Command has shown me how close it is to the other option and that it really isn’t a large enough margin to matter.

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  • Best way to access database from android

    - by Brandon Delany
    I am working on a Android app and I have a dilemma. I have a list of Objects. I have to update each of these objects with a database. I have 2 methods: Method 1: I can loop through the Objects. For each object I can connect to the server, update it, and then move on to the next Object, and so forth. Method 2: I can store the Objects in a list, send the whole list to the server, update it on the server side, then return a list of updated objects. My questions are: Which method is faster? Which method is easier on the phone's battery? By the way, Method 1 is easier for me to code :). Thank you.

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  • Multi-Threading in .NET

    - by AIC
    Hi all.. I wrote this program, that is supposed to read about 5000 email address and send an pre-defined html mail. I am using the background worker component. The problem is this: I have wired up the method who is supposed to send the mail. But I am calling another method that is supposed to append the body html to the salutation, like public string GiveMeFullHtml(string personname) ... "Dear Mr. John Doe" + HTML ... It seems that when it hits this method call, operation completes. IUt only sends the first mail and completes. I think because the HTML string method is on another thread or sth like that. Can you give me a little insight. Do I have to get everything done in the very same method when using multi-threading? Thanks in advance

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  • Why does GetClusterShape return null when the cluster specification was retrieved through the GetClu

    - by Markus Olsson
    Suppose I have a virtual earth shape layer called shapeLayer1 (my creative energy is apparently at an alltime low). When i call the GetClusteredShapes method I get an array of VEClusterSpecification objects that represent each and every one of my currently visible clusters; no problem there. But when I call the GetClusterShape() method it returns null... null! Why on earth would it do that? I used firebug to confirm that the private variable of the VEClusterSpecification that's supposed to hold a reference to the shape is indeed null so it's not the method that's causing the problem. Some have suggested that this is actually documented behavior Returns null if a VEClusterSpecification object was returned from the VEShapeLayer.GetClusteredShapes Method But looking at the current MSDN documentation for the VEShape class it says: Returns if a VEClusterSpecification object was returned from the VEShapeLayer.GetClusteredShapes Method Is this a bug or a feature? Is there any known workarounds or (if it is a bug) some plan on when they are going to fix it?

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  • Strange thing about .NET 4.0 filesystem enumeration functionality

    - by codymanix
    I just read a page of "Whats new .NET Framework 4.0". I have trouble understanding the last paragraph: To remove open handles on enumerated directories or files Create a custom method (or function in Visual Basic) to contain your enumeration code. Apply the MethodImplAttribute attribute with the NoInlining option to the new method. For example: [MethodImplAttribute(MethodImplOptions.NoInlining)] Private void Enumerate() Include the following method calls, to run after your enumeration code: * The GC.Collect() method (no parameters). * The GC.WaitForPendingFinalizers() method. Why the attribute NoInlining? What harm would inlining do here? Why call the garbage collector manually, why not making the enumerator implement IDisposable in the first place? I suspect they use FindFirstFile()/FindNextFile() API calls for the imlementation, so FindClose() has to be called in any case if the enumeration is done.

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  • Creating ADF Faces Comamnd Button at Runtime

    - by Frank Nimphius
    Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} In ADF Faces, the command button is an instance of RichCommandButton and can be created at runtime. While creating the button is not difficult at all, adding behavior to it requires knowing about how to dynamically create and add an action listener reference. The example code below shows two methods: The first method, handleButtonPress is a public method exposed on a managed bean. public void handleButtonPress(ActionEvent event){   System.out.println("Event handled");   //optional: partially refresh changed components if command   //issued as a partial submit } The second method is called in response to a user interaction or on page load and dynamically creates and adds a command button. When the button is pressed, the managed bean method – the action handler – defined above is called. The action handler is referenced using EL in the created MethodExpression instance. If the managed bean is in viewScope, backingBeanScope or pageFlowsScope, then you need to add these scopes as a prefix to the EL (as you would when configuring the managed bean reference at design time) //Create command button and add it as a child to the parent component that is passed as an //argument to this method private void reateCommandButton(UIComponent parent){   RichCommandButton edit = new RichCommandButton();   //make the request partial   edit.setPartialSubmit(true);   edit.setText("Edit");                             //compose the method expression to invoke the event handler   FacesContext fctx = FacesContext.getCurrentInstance();   Application application = fctx.getApplication();   ExpressionFactory elFactory = application.getExpressionFactory();   ELContext elContext = facesCtx.getELContext();   MethodExpression methodExpressio = null;   //Make sure the EL expression references a valid managed bean method. Ensure   //the bean scope is properly addressed    methodExpression =  elFactory.createMethodExpression(                              elContext,"#{myRequestScopeBean.handleButtonPress}",                             Object.class,new Class[] {ActionEvent.class});   //Create the command buttonaction listener reference   MethodExpressionActionListener al = null;          al= new MethodExpressionActionListener(methodExpression);    edit.addActionListener(al);     //add new command button to parent component and PPR the component for     //the button to show    parent.getChildren().add(edit);    AdfFacesContext adfFacesContext = AdfFacesContext.getCurrentInstance();     adfFacesContext.addPartialTarget(parent);  }

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  • Spring/Hibernate: InvocationTargetException when deleting entity

    - by niklassaers
    I'm sorry if this question is a bit vague, but I'm quite confused. I've got a controller that calls a service to delete an entity and then create an entity in its place. In the service, I've got my DAO, and my entity, and I want to delete my entity, so I call DAO.delete(entity); Then, seemingly out of nowhere, I get an InvocationTargetException. The parameters here are: method: public org.springframework.web.servlet.ModelAndView tld.myproject.view.web.controller.MyController.replaceEntity(org.springframework.web.multipart.MultipartFile,javax.servlet.http.HttpServletRequest) target: tld.myproject.view.web.controller.MyController@185918e args: [org.springframework.web.multipart.commons.CommonsMultipartFile@14812a6, org.springframework.web.multipart.support.DefaultMultipartHttpServletRequest@c08a64] ex: java.lang.reflect.InvocationTargetException private Object doInvokeMethod(Method method, Object target, Object[] args) throws Exception { ReflectionUtils.makeAccessible(method); try { return method.invoke(target, args); } catch (InvocationTargetException ex) { ReflectionUtils.rethrowException(ex.getTargetException()); } throw new IllegalStateException("Should never get here"); } Does anyone have a suggestion to what's going on? Anything I can use in my debugging? Cheers Nik

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  • Should a Unit-test replicate functionality or Test output?

    - by Daniel Beardsley
    I've run into this dilemma several times. Should my unit-tests duplicate the functionality of the method they are testing to verify it's integrity? OR Should unit tests strive to test the method with numerous manually created instances of inputs and expected outputs? I'm mainly asking the question for situations where the method you are testing is reasonably simple and it's proper operation can be verified by glancing at the code for a minute. Simplified example (in ruby): def concat_strings(str1, str2) return str1 + " AND " + str2 end Simplified functionality-replicating test for the above method: def test_concat_strings 10.times do str1 = random_string_generator str2 = random_string_generator assert_equal (str1 + " AND " + str2), concat_strings(str1, str2) end end I understand that most times the method you are testing won't be simple enough to justify doing it this way. But my question remains; is this a valid methodology in some circumstances (why or why not)?

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  • Keypress detection wont work after seemingly unrelated code change

    - by LukeZaz
    I'm trying to have the Enter key cause a new 'map' to generate for my game, but for whatever reason after implementing full-screen in it the input check won't work anymore. I tried removing the new code and only pressing one key at a time, but it still won't work. Here's the check code and the method it uses, along with the newMap method: public class Game1 : Microsoft.Xna.Framework.Game { // ... protected override void Update(GameTime gameTime) { // ... // Check if Enter was pressed - if so, generate a new map if (CheckInput(Keys.Enter, 1)) { blocks = newMap(map, blocks, console); } // ... } // Method: Checks if a key is/was pressed public bool CheckInput(Keys key, int checkType) { // Get current keyboard state KeyboardState newState = Keyboard.GetState(); bool retType = false; // Return type if (checkType == 0) { // Check Type: Is key currently down? if (newState.IsKeyDown(key)) { retType = true; } else { retType = false; } } else if (checkType == 1) { // Check Type: Was the key pressed? if (newState.IsKeyDown(key)) { if (!oldState.IsKeyDown(key)) { // Key was just pressed retType = true; } else { // Key was already pressed, return false retType = false; } } } // Save keyboard state oldState = newState; // Return result if (retType == true) { return true; } else { return false; } } // Method: Generate a new map public List<Block> newMap(Map map, List<Block> blockList, Console console) { // Create new map block coordinates List<Vector2> positions = new List<Vector2>(); positions = map.generateMap(console); // Clear list and reallocate memory previously used up by it blockList.Clear(); blockList.TrimExcess(); // Add new blocks to the list using positions created by generateMap() foreach (Vector2 pos in positions) { blockList.Add(new Block() { Position = pos, Texture = dirtTex }); } // Return modified list return blockList; } // ... } and the generateMap code: // Generate a list of Vector2 positions for blocks public List<Vector2> generateMap(Console console, int method = 0) { ScreenTileWidth = gDevice.Viewport.Width / 16; ScreenTileHeight = gDevice.Viewport.Height / 16; maxHeight = gDevice.Viewport.Height; List<Vector2> blockLocations = new List<Vector2>(); if (useScreenSize == true) { Width = ScreenTileWidth; Height = ScreenTileHeight; } else { maxHeight = Height; } int startHeight = -500; // For debugging purposes, the startHeight is set to an // hopefully-unreachable value - if it returns this, something is wrong // Methods of land generation /// <summary> /// Third version land generation /// Generates a base land height as the second version does /// but also generates a 'max change' value which determines how much /// the land can raise or lower by which it now does by a random amount /// during generation /// </summary> if (method == 0) { // Get the land height startHeight = rnd.Next(1, maxHeight); int maxChange = rnd.Next(1, 5); // Amount ground will raise/lower by int curHeight = startHeight; for (int w = 0; w < Width; w++) { // Run a chance to lower/raise ground level int changeBy = rnd.Next(1, maxChange); int doChange = rnd.Next(0, 3); if (doChange == 1 && !(curHeight <= (1 + maxChange))) { curHeight = curHeight - changeBy; } else if (doChange == 2 && !(curHeight >= (29 - maxChange))) { curHeight = curHeight + changeBy; } for (int h = curHeight; h < Height; h++) { // Location variables float x = w * 16; float y = h * 16; blockLocations.Add(new Vector2(x, y)); } } console.newMsg("[INFO] Cur, height change maximum: " + maxChange.ToString()); } /// <summary> /// Second version land generator /// Generates a solid mass of land starting at a random height /// derived from either screen height or provided height value /// </summary> else if (method == 1) { // Get the land height startHeight = rnd.Next(0, 30); for (int w = 0; w < Width; w++) { for (int h = startHeight; h < ScreenTileHeight; h++) { // Location variables float x = w * 16; float y = h * 16; // Add a tile at set location blockLocations.Add(new Vector2(x, y)); } } } /// <summary> /// First version land generator /// Generates land completely randomly either across screen or /// in a box set by Width and Height values /// </summary> else { // For each tile in the map... for (int w = 0; w < Width; w++) { for (int h = 0; h < Height; h++) { // Location variables float x = w * 16; float y = h * 16; // ...decide whether or not to place a tile... if (rnd.Next(0, 2) == 1) { // ...and if so, add a tile at that location. blockLocations.Add(new Vector2(x, y)); } } } } console.newMsg("[INFO] Cur, base height: " + startHeight.ToString()); return blockLocations; } I never touched any of the above code for this when it broke - changing keys won't seem to fix it. Despite this, I have camera movement set inside another Game1 method that uses WASD and works perfectly. All I did was add a few lines of code here: private int BackBufferWidth = 1280; // Added these variables private int BackBufferHeight = 800; public Game1() { graphics = new GraphicsDeviceManager(this); graphics.PreferredBackBufferWidth = BackBufferWidth; // and this graphics.PreferredBackBufferHeight = BackBufferHeight; // this Content.RootDirectory = "Content"; this.graphics.IsFullScreen = true; // and this } When I try adding a console line to be printed in the event the key is pressed, it seems that the If is never even triggered despite the correct key being pressed.

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  • .Net Reflection - Calling unexisting methods

    - by Joaozinho das Couves
    Lets say i call method M1 on class A using reflection. The method does not exist. Is there any way to put a handler on class A that says, "someone is trying to execute method M1"? Or Is it possible to add a method dinamically to a class? I want to add a method M1...Mn that always does MyStaticClass.DoAction("M1...Mn"); Something like: string methodName = "M1". A.AddMethod(methodname,x = MyStaticClass.DoAction(x)); Thanks

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  • Django database caching

    - by hekevintran
    I have a Django form that uses an integer field to lookup a model object by its primary key. The form has a save() method that uses the model object referred to by the integer field. The model's manager's get() method is called twice, once in the clean method and once in the save() method: class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is the first call to get MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): id_a = self.cleaned_data['id_a'] # here is the second call to get my_model_object = MyModel.objects.get(id=id_a) # do other stuff I wasn't sure whether this hits the database two times or one time so I returned the object itself in the clean method so that I could avoid a second get() call. Does calling get() hit the database two times? Or is the object cached in the thread? class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is my workaround return MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): # looking up the cleaned value returns the model object my_model_object = self.cleaned_data['id_a'] # do other stuff

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  • Lambda&rsquo;s for .NET made easy&hellip;

    - by mbcrump
    The purpose of my blog is to explain things for a beginner to intermediate c# programmer. I’ve seen several blog post that use lambda expressions always assuming the audience is familiar with them. The purpose of this post is to make them simple and easily understood. Let’s begin with a definition. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. So anonymous function… delegates or expression tree types? I don’t get it??? Confused yet?   Lets break this into a few definitions and jump right into the code. anonymous function – is an "inline" statement or expression that can be used wherever a delegate type is expected. delegate - is a type that references a method. Once a delegate is assigned a method, it behaves exactly like that method. The delegate method can be used like any other method, with parameters and a return value. Expression trees - represent code in a tree-like data structure, where each node is an expression, for example, a method call or a binary operation such as x < y.   Don’t worry if this still sounds confusing, lets jump right into the code with a simple 3 line program. We are going to use a Function Delegate (all you need to remember is that this delegate returns a value.) Lambda expressions are used most commonly with the Func and Action delegates, so you will see an example of both of these. Lambda Expression 3 lines. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Func<int, int> myfunc = x => x *x;             Console.WriteLine(myfunc(6).ToString());             Console.ReadLine();         }       } } Is equivalent to Old way of doing it. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {               Console.WriteLine(myFunc(6).ToString());             Console.ReadLine();         }            static int myFunc(int x)          {              return x * x;            }       } } In the example, there is a single parameter, x, and the expression is x*x. I’m going to stop here to make sure you are still with me. A lambda expression is an unnamed method written in place of a delegate instance. In other words, the compiler converts the lambda expression to either a : A delegate instance An expression tree All lambda have the following form: (parameters) => expression or statement block Now look back to the ones we have created. It should start to sink in. Don’t get stuck on the => form, use it as an identifier of a lambda. A Lamba expression can also be written in the following form: Lambda Expression. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Func<int, int> myFunc = x =>             {                 return x * x;             };               Console.WriteLine(myFunc(6).ToString());             Console.ReadLine();         }       } } This form may be easier to read but consumes more space. Lets try an Action delegate – this delegate does not return a value. Action Delegate example. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Action<string> myAction = (string x) => { Console.WriteLine(x); };             myAction("michael has made this so easy");                                   Console.ReadLine();         }       } } Lambdas can also capture outer variables (such as the example below) A lambda expression can reference the local variables and parameters of the method in which it’s defined. Outer variables referenced by a lambda expression are called captured variables. Capturing Outer Variables using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             string mike = "Michael";             Action<string> myAction = (string x) => {                 Console.WriteLine("{0}{1}", mike, x);          };             myAction(" has made this so easy");                                   Console.ReadLine();         }       } } Lamba’s can also with a strongly typed list to loop through a collection.   Used w a strongly typed list. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             List<string> list = new List<string>() { "1", "2", "3", "4" };             list.ForEach(s => Console.WriteLine(s));             Console.ReadLine();         }       } } Outputs: 1 2 3 4 I think this will get you started with Lambda’s, as always consult the MSDN documentation for more information. Still confused? Hopefully you are not.

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