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• linq where clause and count result in null exception.

  - by nestling

  The code below works unless p.School.SchoolName turns out to be null, in which case it results in a NullReferenceException. if (ExistingUsers.Where(p => p.StudentID == item.StaffID && p.School.SchoolName == item.SchoolID).Count() > 0) { // Do stuff. } ExistingUsers is a list of users: public List<User> ExistingUsers; Here is the relevant portion of the stacktrace: System.NullReferenceException: Object reference not set to an instance of an object. at System.Linq.Enumerable.WhereListIterator1.MoveNext() at System.Linq.Enumerable.Count[TSource](IEnumerable1 source) How should I handle this where clause? Thanks very much in advance.

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• Rails - embedded polymorphic comment list + add comment form - example?

  - by odigity

  Hey, all. Working on my first Rails app. I've searched all around - read a bunch of tutorials, articles, and forum posts, watched some screencasts, and I've found a few examples that come close to what I'm trying to do (notably http://railscasts.com/episodes/154-polymorphic-association and ep 196 about nested model forms), but not exactly. I have two models (Podcast and BlogPost) that need to be commentable, and I have a Comment model that is polymorphically related to both. The railscasts above had a very similar example (ep 154), but Ryan used a full set of nested routes, so there were specific templates for adding and editing comments. What I want to do is show the list of comments right on the Podcast or BlogPost page, along with an Add Comment form at the bottom. I don't need a separate add template/route, and I don't need the ability to edit, only delete. This is a pretty common design on the web, but I can't find a Rails example specifically about this pattern. Here's my current understanding: I need routes for the create and delete actions, of course, but there are no templates associated with those. I'm also guessing that the right approach is to create a partial that can be included at the bottom of both the Podcast and BlogPost show template. The logical name for the partial seems to me to be something like _comments.html.haml. I know it's a common convention to have the object passed to the partial be named after the template, but calling the object 'comments' seems to not match my use case, since what I really need to pass is the commentable object (Podcast or BlogPost). So, I guess I'd use the locals option for the render partial call? (:commentable = @podcast). Inside the partial, I could call commentable.comments to get the comments collection, render that with a second partial (this time with the conventional use case, calling the partial _comment.html.haml), then create a form that submits to... what? REST-wise, it should be a POST to the collection, which would be /podcast|blogpost/:id/comments, and I think the helper for that is podcast_comments_path(podcast) if it were a podcast - not sure what to do though, since I'm using polymorphic comments. That would trigger the Comment.create action, which would then need to redirect back to the podcast|blogpost path /podcast|blogpost/:id. It's all a bit overwhelming, which is why I was really hoping to find a screencast or example that specifically implements this design.

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• Reference a GNU C (POSIX) DLL built in GCC against Cygwin, from C#/NET

  - by Dale Halliwell

  Here is what I want: I have a huge legacy C/C++ codebase written for POSIX, including some very POSIX specific stuff like pthreads. This can be compiled on Cygwin/GCC and run as an executable under Windows with the Cygwin DLL. What I would like to do is build the codebase itself into a Windows DLL that I can then reference from C# and write a wrapper around it to access some parts of it programatically. I have tried this approach with the very simple "hello world" example at http://www.cygwin.com/cygwin-ug-net/dll.html and it doesn't seem to work. #include <stdio.h> extern "C" __declspec(dllexport) int hello(); int hello() { printf ("Hello World!\n"); return 42; } I believe I should be able to reference a DLL built with the above code in C# using something like: [DllImport("kernel32.dll")] public static extern IntPtr LoadLibrary(string dllToLoad); [DllImport("kernel32.dll")] public static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName); [DllImport("kernel32.dll")] public static extern bool FreeLibrary(IntPtr hModule); [UnmanagedFunctionPointer(CallingConvention.Cdecl)] private delegate int hello(); static void Main(string[] args) { var path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "helloworld.dll"); IntPtr pDll = LoadLibrary(path); IntPtr pAddressOfFunctionToCall = GetProcAddress(pDll, "hello"); hello hello = (hello)Marshal.GetDelegateForFunctionPointer( pAddressOfFunctionToCall, typeof(hello)); int theResult = hello(); Console.WriteLine(theResult.ToString()); bool result = FreeLibrary(pDll); Console.ReadKey(); } But this approach doesn't seem to work. LoadLibrary returns null. It can find the DLL (helloworld.dll), it is just like it can't load it or find the exported function. I am sure that if I get this basic case working I can reference the rest of my codebase in this way. Any suggestions or pointers, or does anyone know if what I want is even possible? Thanks. Edit: Examined my DLL with Dependency Walker (great tool, thanks) and it seems to export the function correctly. Question: should I be referencing it as the function name Dependency Walker seems to find (_Z5hellov)? Edit2: Just to show you I have tried it, linking directly to the dll at relative or absolute path (i.e. not using LoadLibrary): [DllImport(@"C:\.....\helloworld.dll")] public static extern int hello(); static void Main(string[] args) { int theResult = hello(); Console.WriteLine(theResult.ToString()); Console.ReadKey(); } This fails with: "Unable to load DLL 'C:.....\helloworld.dll': Invalid access to memory location. (Exception from HRESULT: 0x800703E6) *Edit 3: * Oleg has suggested running dumpbin.exe on my dll, this is the output: Dump of file helloworld.dll File Type: DLL Section contains the following exports for helloworld.dll 00000000 characteristics 4BD5037F time date stamp Mon Apr 26 15:07:43 2010 0.00 version 1 ordinal base 1 number of functions 1 number of names ordinal hint RVA name 1 0 000010F0 hello Summary 1000 .bss 1000 .data 1000 .debug_abbrev 1000 .debug_info 1000 .debug_line 1000 .debug_pubnames 1000 .edata 1000 .eh_frame 1000 .idata 1000 .reloc 1000 .text Edit 4 Thanks everyone for the help, I managed to get it working. Oleg's answer gave me the information I needed to find out what I was doing wrong. There are 2 ways to do this. One is to build with the gcc -mno-cygwin compiler flag, which builds the dll without the cygwin dll, basically as if you had built it in MingW. Building it this way got my hello world example working! However, MingW doesn't have all the libraries that cygwin has in the installer, so if your POSIX code has dependencies on these libraries (mine had heaps) you can't do this way. And if your POSIX code didn't have those dependencies, why not just build for Win32 from the beginning. So that's not much help unless you want to spend time setting up MingW properly. The other option is to build with the Cygwin DLL. The Cygwin DLL needs an initialization function init() to be called before it can be used. This is why my code wasn't working before. The code below loads and runs my hello world example. //[DllImport(@"hello.dll", EntryPoint = "#1",SetLastError = true)] //static extern int helloworld(); //don't do this! cygwin needs to be init first [DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)] static extern IntPtr GetProcAddress(IntPtr hModule, string procName); [DllImport("kernel32", SetLastError = true)] static extern IntPtr LoadLibrary(string lpFileName); public delegate int MyFunction(); static void Main(string[] args) { //load cygwin dll IntPtr pcygwin = LoadLibrary("cygwin1.dll"); IntPtr pcyginit = GetProcAddress(pcygwin, "cygwin_dll_init"); Action init = (Action)Marshal.GetDelegateForFunctionPointer(pcyginit, typeof(Action)); init(); IntPtr phello = LoadLibrary("hello.dll"); IntPtr pfn = GetProcAddress(phello, "helloworld"); MyFunction helloworld = (MyFunction)Marshal.GetDelegateForFunctionPointer(pfn, typeof(MyFunction)); Console.WriteLine(helloworld()); Console.ReadKey(); } Thanks to everyone that answered~~

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• How to play multiple audio sources simultaneously in Silverlight

  - by Shurup

  I want to play simultaneous multiply audio sources in Silverlight. So I've created a prototype in Silverlight 4 that should play a two mp3 files containing the same ticks sound with an intervall 1 second. So these files must be sounded as one sound if they will be played together with any whole second offsets (0 and 1, 0 and 2, 1 and 1 seconds, etc.) I my prototype I use two MediaElement (me and me2) objects. DateTime startTime; private void Play_Clicked(object sender, RoutedEventArgs e) { me.SetSource(new FileStream(file1), FileMode.Open))); me2.SetSource(new FileStream(file2), FileMode.Open))); var timer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(1) }; timer.Tick += RefreshData; timer.Start(); } First file should be played at 00:00 sec. and the second in 00:02 second. void RefreshData(object sender, EventArgs e) { if(me.CurrentState != MediaElementState.Playing) { startTime = DateTime.Now; me.Play(); return; } var elapsed = DateTime.Now - startTime; if(me2.CurrentState != MediaElementState.Playing && elapsed >= TimeSpan.FromSeconds(2)) { me2.Play(); ((DispatcherTimer)sender).Stop(); } } The tracks played every time different and not simultaneous as they should (as one sound). Addition: I've tested a code from the Bobby's answer. private void Play_Clicked(object sender, RoutedEventArgs e) { me.SetSource(new FileStream(file1), FileMode.Open))); me2.SetSource(new FileStream(file2), FileMode.Open))); // This code plays well enough. // me.Play(); // me2.Play(); // But adding the 2 second offset using the timer, // they play no simultaneous. var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(2) }; timer.Tick += (source, arg) => { me2.Play(); ((DispatcherTimer)source).Stop(); }; timer.Start(); } Is it possible to play them together using only one MediaElement or any implementation of MediaStreamSource that can play multiply sources?

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• Psuedo-Backwards Builder Pattern?

  - by Avid Aardvark

  In a legacy codebase I have a very large class with far too many fields/responsibilities. Imagine this is a Pizza object. It has highly granular fields like: hasPepperoni hasSausage hasBellPeppers I know that when these three fields are true, we have a Supreme pizza. However, this class is not open for extension or change, so I can't add a PizzaType, or isSupreme(), etc. Folks throughout the codebase duplicate the same "if(a && b && c) then isSupreme)" logic all over place. This issue comes up for quite a few concepts, so I'm looking for a way to deconstruct this object into many subobjects, e.g. a pseudo-backwards Builder Pattern. PizzaType pizzaType = PizzaUnbuilder.buildPizzaType(Pizza); //PizzaType.SUPREME Dough dough = PizzaUnbuilder.buildDough(Pizza); Is this the right approach? Is there a pattern for this already? Thanks!

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• How to improve the builder pattern?

  - by tangens

  Motivation Recently I searched for a way to initialize a complex object without passing a lot of parameter to the constructor. I tried it with the builder pattern, but I don't like the fact, that I'm not able to check at compile time if I really set all needed values. Traditional builder pattern When I use the builder pattern to create my Complex object, the creation is more "typesafe", because it's easier to see what an argument is used for: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) ... .build(); But now I have the problem, that I can easily miss an important parameter. I can check for it inside the build() method, but that is only at runtime. At compile time there is nothing that warns me, if I missed something. Enhanced builder pattern Now my idea was to create a builder, that "reminds" me if I missed a needed parameter. My first try looks like this: public class Complex { private String m_first; private String m_second; private String m_third; private Complex() {} public static class ComplexBuilder { private Complex m_complex; public ComplexBuilder() { m_complex = new Complex(); } public Builder2 setFirst( String first ) { m_complex.m_first = first; return new Builder2(); } public class Builder2 { private Builder2() {} Builder3 setSecond( String second ) { m_complex.m_second = second; return new Builder3(); } } public class Builder3 { private Builder3() {} Builder4 setThird( String third ) { m_complex.m_third = third; return new Builder4(); } } public class Builder4 { private Builder4() {} Complex build() { return m_complex; } } } } As you can see, each setter of the builder class returns a different internal builder class. Each internal builder class provides exactly one setter method and the last one provides only a build() method. Now the construction of an object again looks like this: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) .build(); ...but there is no way to forget a needed parameter. The compiler wouldn't accept it. Optional parameters If I had optional parameters, I would use the last internal builder class Builder4 to set them like a "traditional" builder does, returning itself. Questions Is this a well known pattern? Does it have a special name? Do you see any pitfalls? Do you have any ideas to improve the implementation - in the sense of fewer lines of code?

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• ICommand.CanExecute being passed null even though CommandParameter is set...

  - by chaiguy

  I have a tricky problem where I am binding a ContextMenu to a set of ICommand-derived objects, and setting the Command and CommandParameter properties on each MenuItem via a style: <ContextMenu ItemsSource="{Binding Source={x:Static OrangeNote:Note.MultiCommands}}"> <ContextMenu.Resources> <Style TargetType="MenuItem"> <Setter Property="Header" Value="{Binding Path=Title}" /> <Setter Property="Command" Value="{Binding}" /> <Setter Property="CommandParameter" Value="{Binding Source={x:Static OrangeNote:App.Screen}, Path=SelectedNotes}" /> ... However, while ICommand.Execute( object ) gets passed the set of selected notes as it should, ICommand.CanExecute( object ) (which is called when the menu is created) is getting passed null. I've checked and the selected notes collection is properly instantiated before the call is made (in fact it's assigned a value in its declaration, so it is never null). I can't figure out why CanEvaluate is getting passed null.

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• java.lang.NoSuchMethodError: main when starting HelloWorld with Eclipse Scala plugin

  - by Matt Sheppard

  I've just been playing with Scala, and installed the Eclipse plugin as described at http://www.scala-lang.org/node/94, but after entering the "Hello World" test example and setting up the run configuration as described, I get the following error Exception in thread "main" java.lang.NoSuchMethodError: main For reference the code is package hello object HelloWorld extends Application { println("Hello World!") } I've tinkered a bit with the obvious solutions (adding a main method, adding a singleton object with a main method) but I'm clearly doing something wrong. Can anyone get their test example to work, or point out what I am doing wrong?

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• Custom Control Not Playing Nice With PropertyGrid

  - by lumberjack4

  I have a class that is implementing a custom ToolStripItem. Everything seems to work great until I try to add the item to a ContextMenuStrip at design time. If I try to add my custom control straight from the ContextMenuStrip the PropertyGrid freezes up and will not let me modify my Checked or Text properties. But if I go into the ContextMenuStrip PropertyGrid and add my custom control through the Items(...) property, I can modify the custom control just fine within that dialog. I'm not sure if I'm missing an attribute somewhere of if its a problem with the underlying code. Here is a copy of the CustomToolStripItem class. As you can see, its a very simple class. [ToolStripItemDesignerAvailability(ToolStripItemDesignerAvailability.ContextMenuStrip)] public class CustomToolStripItem : ToolStripControlHost { #region Public Properties [Description("Gets or sets a value indicating whether the object is in the checked state")] [ReadOnly(false)] public bool Checked { get { return checkBox.Checked; } set { checkBox.Checked = value; } } [Description("Gets or sets the object's text")] [ReadOnly(false)] public override string Text { get { return checkBox.Text; } set { checkBox.Text = value; } } #endregion Public Properties #region Public Events public event EventHandler CheckedChanged; #endregion Public Events #region Constructors public CustomToolStripItem() : base(new FlowLayoutPanel()) { // Setup the FlowLayoutPanel. controlPanel = (FlowLayoutPanel)base.Control; controlPanel.BackColor = Color.Transparent; // Add the child controls. checkBox.AutoSize = true; controlPanel.Controls.Add(checkBox); ContextMenuStrip strip = new ContextMenuStrip(); } #endregion Constructors #region Protected Methods protected override void OnSubscribeControlEvents(Control control) { base.OnSubscribeControlEvents(control); checkBox.CheckedChanged += new EventHandler(CheckChanged); } protected override void OnUnsubscribeControlEvents(Control control) { base.OnUnsubscribeControlEvents(control); checkBox.CheckedChanged -= new EventHandler(CheckChanged); } #endregion Protected Methods #region Private Methods private void CheckChanged(object sender, EventArgs e) { // Throw the CustomToolStripItem's CheckedChanged event EventHandler handler = CheckedChanged; if (handler != null) { handler(sender, e); } } #endregion Private Methods #region Private Fields private FlowLayoutPanel controlPanel; private CheckBox checkBox = new CheckBox(); #endregion Private Fields }

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• Problem with core data migration mapping model

  - by dpratt

  I have an iphone app that uses Core Data to do storage. I have successfully deployed it, and now I'm working on the second version. I've run into a problem with the data model that will require a few very simple data transformations at the time that the persistent store gets upgraded, so I can't just use the default inferred mapping model. My object model is stored in an .xcdatamodeld bundle, with versions 1.0 and 1.1 next to each other. Version 1.1 is set as the active version. Everything works fine when I use the default migration behavior and set NSInferMappingModelAutomaticallyOption to YES. My sqlite storage gets upgraded from the 1.0 version of the model, and everything is good except for, of course, the few transformations I need done. As an additional experimental step, I added a new Mapping Model to the core data model bundle, and have made no changes to what xcode generated. When I run my app (with an older version of the data store), I get the following * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Object's persistent store is not reachable from this NSManagedObjectContext's coordinator' What am I doing wrong? Here's my code for to get the managed object model and the persistent store coordinator. - (NSPersistentStoreCoordinator *)persistentStoreCoordinator { if (_persistentStoreCoordinator != nil) { return _persistentStoreCoordinator; } _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"gti_store.sqlite"]]; NSError *error; NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:options error:&error]) { NSLog(@"Eror creating persistent store coodinator - %@", [error localizedDescription]); } return _persistentStoreCoordinator; } - (NSManagedObjectModel *)managedObjectModel { if(_managedObjectModel == nil) { _managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain]; NSDictionary *entities = [_managedObjectModel entitiesByName]; //add a sort descriptor to the 'Foo' fetched property so that it can have an ordering - you can't add these from the graphical core data modeler NSEntityDescription *entity = [entities objectForKey:@"Foo"]; NSFetchedPropertyDescription *fetchedProp = [[entity propertiesByName] objectForKey:@"orderedBar"]; NSSortDescriptor* sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"index" ascending:YES] autorelease]; NSArray* sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil]; [[fetchedProp fetchRequest] setSortDescriptors:sortDescriptors]; } return _managedObjectModel; }

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• I keep on getting "save operation failure" after any change on my XCode Data Model

  - by Philip Schoch

  I started using Core Data for iPhone development. I started out by creating a very simple entity (called Evaluation) with just one string property (called evaluationTopic). I had following code for inserting a fresh string: - (void)insertNewObject { // Create a new instance of the entity managed by the fetched results controller. NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity]; NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context]; // If appropriate, configure the new managed object. [newManagedObject setValue:@"My Repeating String" forKey:@"evaluationTopic"]; // Save the context. NSError *error; if (![context save:&error]) { // Handle the error... } [self.tableView reloadData]; } This worked perfectly fine and by pushing the +button a new "My Repeating String" would be added to the table view and be in persistent store. I then pressed "Design - Add Model Version" in XCode. I added three entities to the existing entity and also added new properties to the existing "Evaluation" entity. Then, I created new files off the entities by pressing "File - New File - Managed Object Classes" and created a new .h and .m file for my four entities, including the "Evaluation" entity with Evaluation.h and Evaluation.m. Now I changed the model version by setting "Design - Data Model - Set Current Version". After having done all this, I changed my insertMethod: - (void)insertNewObject { // Create a new instance of the entity managed by the fetched results controller. NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity]; Evaluation *evaluation = (Evaluation *) [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context]; // If appropriate, configure the new managed object. [evaluation setValue:@"My even new string" forKey:@"evaluationSpeechTopic"]; // Save the context. NSError *error; if (![context save:&error]) { // Handle the error... } [self.tableView reloadData]; } This does not work though! Every time I want to add a row the simulator crashes and I get the following: "NSInternalInconsistencyException', reason: 'This NSPersistentStoreCoordinator has no persistent stores. It cannot perform a save operation.'" I had this error before I knew about creating new version after changing anything on the datamodel, but why is this still coming up? Do I need to do any mapping (even though I just added entities and properties that did not exist before?). In the Apple Dev tutorial it sounds very easy but I have been struggling with this for long time, never worked after changing model version.

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• Spring MVC - Cannot map request parameters as a Map parameter in method?

  - by Ken Chen

  What I want to do is passing a map to the method in Controller using @RequestParam, but it seems not working. While this is working in Struts 2. Below is what I am trying: In JSP using JQuery: var order = {}; order['seq'] = "ASC"; var criteria = {}; criteria['label'] = "Directory"; $.post(context + 'menu/list', {"orders" : order, "criterias" : criteria} The parameters I am trying to post is an 'map' object order and criteria for listing menu. In Java: @RequestMapping("/{collection}/list") public @ResponseBody Map<String, ? extends Object> list(@PathVariable String collection, @RequestParam("criterias") Map<String, String> criteria, @RequestParam("orders") Map<String, String> order) { However, when I print out the map criteria & order in Java, it takes all value as below: Criteria: {criterias[label]=Directory, orders[seq]=ASC} Order: {criterias[label]=Directory, orders[seq]=ASC} Can @RequestParam in Spring be used to init a Map parameter?

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• How to embed PDF in a web page using Acrobat Reader instead of Acrobat.

  - by Lachlan Roche

  I have a pdf form that uses Acrobat 8 features. The form contains Javascript that interacts with the hosting web page. Some of my Windows users have both Adobe Acrobat and Acrobat Reader installed, and need Adobe Acrobat to be the default handler for pdf files. The users with Adobe Acrobat 7 are unable to use the form, even though they might have Acrobat Reader 8 or 9 installed. Currently, the PDF is embedded like this: <object id="host" data="/path/to/document.pdf" type="application/pdf" width="900" height="550" ></object>

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• NDepend query methods/types in framework assembly being used by other assemblies/types

  - by icelava

  I am trying to determine which types or methods in a base framework assembly are being used by other assemblies in the application system. I cannot seem to find a straight-cut query to do that. What i have to do is first determine which assemblies are directly using the framework assembly, then manually list them in a second query SELECT TYPES FROM ASSEMBLIES "IBM.Data.DB2" WHERE IsDirectlyUsedBy "ASSEMBLY:FirstDirectUsedByAssebmly" OR IsDirectlyUsedBy "ASSEMBLY:SecondDirectUsedByAssebmly" OR IsDirectlyUsedBy "ASSEMBLY:ThirdDirectUsedByAssebmly" OR IsDirectlyUsedBy "ASSEMBLY:FourthDirectUsedByAssebmly" Is there a better/faster way to query for this? Additionally, the query results are focused on the matched types only. The Dependency graph or matrix exported only shows details of those. I do not know how to render a graph that shows those types or methods plus show the dependent types/methods from other assemblies that are consuming them?

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• Running a Java daemon with a GWT front-end served by embedded Jetty

  - by BinaryMuse

  Greetings, coders, Background Info and Code I am trying to create a daemon-type program (e.g., it runs constantly, polling for things to do) that is managed by a GWT application (servlets in a WAR) which is in turn served by an embedded Jetty server (using a WebAppContext). I'm having problems making the GWT application aware of the daemon object. For testing things, I currently have two projects: The daemon and embedded Jetty server in one (EmbJetTest), and the GWT application in another (DefaultApp). This is the current state of the code: First, EmbJetTest creates an embedded Jetty server like so, using a ServletContextListener to inject the daemon object into the web application context: EmbJetTest.server = new Server(8080); // Create and start the daemon Daemon daemon = new Daemon(); Thread thread = new Thread(daemon); thread.start(); // war handler WebAppContext waContext = new WebAppContext(); waContext.setContextPath("/webapp"); waContext.setWar("./apps/DefaultApp.war"); waContext.addEventListener(new DaemonLoader(daemon)); // Add it to the server EmbJetTest.server.setHandler(waContext); EmbJetTest.server.setThreadPool(new QueuedThreadPool(10)); // Start the server; join() blocks until we shut down EmbJetTest.server.start(); EmbJetTest.server.join(); // Stop the daemon thread daemon.stopLoop(); Daemon is a very simple object with a couple properties, at the moment. DaemonLoader is the following ServletContextListener implementation: private Daemon daemon; public DaemonLoader(Daemon daemon) { this.daemon = daemon; } @Override public void contextDestroyed(ServletContextEvent arg0) { } @Override public void contextInitialized(ServletContextEvent arg0) { arg0.getServletContext().setAttribute("daemon", this.daemon); } Then, in one of my servlets in the GWT application, I have the following code: Daemon daemon = (Daemon) this.getServletContext().getAttribute("daemon"); However, when I visit localhost:8080/webapp/* and invoke the servlet, this code throws a ClassCastException, even though the classes are of the same type. This StackOverflow answer indicates that this is because the two classes are loaded with different classloaders. Question My question is twofold. Am I even on the right track here? Am I going about this completely the wrong way? Something tells me I am, but I can't think of another way to make the daemon available to both applications. Is there a better way to communicate with the daemon from the GWT application? Should the GWT app own the daemon and somehow start the daemon itself? The daemon needs to run even if no one visits the one of the GWT app's servlets--how could I do this? If I am on the right track, how can I get around the classloader issue? Thanks in advance.

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• jQuery Javascript array 'contains' functionality?

  - by YourMomzThaBomb

  I'm trying to use the jQuery $.inArray function to iterate through an array and if there's an element whose text contains a particular keyword, remove that element. $.inArray is only returning the array index though if the element's text is equal to the keyword. For example given the following array named 'tokens': - tokens {...} Object [0] "Starbucks^25^http://somelink" String [1] "McDonalds^34^" String [2] "BurgerKing^31^https://www.somewhere.com" String And a call to removeElement(tokens, 'McDonalds'); would return the following array: - tokens {...} Object [0] "Starbucks^25^http://somelink" String [1] "BurgerKing^31^https://www.somewhere.com" String I'm guessing this may be possible using the jQuery $.grep or $.each function, or maybe regex. However, I'm not familiar enough with jQuery to accomplish this. Any help would be appreciated!

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• Javassist: how to create proxy of proxy?

  - by Bozho

  I'm creating proxies with javassist ProxyFactory. When creating a single proxy all works fine. However, when I pass a proxied class to the proxying mechanism, it fails with javassist.bytecode.DuplicateMemberException: duplicate method: setHandler in com.mypackage.Bean_$$_javassist_0_$$_javassist_1 I'm creating the proxies with this: public Object createProxiedInstance(Object originalInstance) throws Exception { Class<?> originalClass = instance.getClass(); ProxyFactory factory = new ProxyFactory(); factory.setSuperclass(originalClass); factory.setHandler(new MethodHandler() {..}); Class<T> proxyClass = factory.createClass(); return proxyClass.newInstance(); } So, how do I create proxies of proxies? Update: The actual problems is that each proxy implements the ProxyObject which defines setHandler(..) method. So the 2nd proxy is trying to redefine the method, instead of overriding it in the subclass.

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• Find a HTML control using FindControl in ASP.NET

  - by Yongwei Xing

  Hi akk I add a select control to a ASPX page like below: hgc = new HtmlGenericControl(); hgc.InnerHtml = @"<select runat='server' id='my_selectlist'> \ <option value='volvo'>Volvo</option> \ <option value='saab'>Saab</option> \ <option value='mercedes'>Mercedes</option> \ <option value='audi'>Audi</option> \ </select>"; Then in a Button click event, I use the code below, try to get the value selected HtmlSelect s = (HtmlSelect)hgc.FindControl("my_selectlist"); label.Text = s.Value; I get a error:"Object reference not set to an instance of an object." Does anyone try it before? Best Regards

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• Dynamically generate PDF and email it using django

  - by Shane

  I have a django app that dynamically generates a PDF (using reportlab + pypdf) from user input on an HTML form, and returns the HTTP response with an application/pdf MIMEType. I want to have the option between doing the above, or emailing the generated pdf, but I cannot figure out how to use the EmailMessage class's attach(filename=None, content=None, mimetype=None) method. The documentation doesn't give much of a description of what kind of object content is supposed to be. I've tried a file object and the above application/pdf HTTP response. I currently have a workaround where my view saves a pdf to disk, and then I attach the resulting file to an outgoing email using the attach_file() method. This seems wrong to me, and I'm pretty sure there is a better way.

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• What does it take to prove this Contract.Requires?

  - by John Gietzen

  I have an application that runs through the rounds in a tournament, and I am getting a contract warning on this simplified code structure: public static void LoadState(IList<Object> stuff) { for(int i = 0; i < stuff.Count; i++) { // Contract.Assert(i < stuff.Count); // Contract.Assume(i < stuff.Count); Object thing = stuff[i]; Console.WriteLine(thing.ToString()); } } The warning is: contracts: requires unproven: index < @this.Count What am I doing wrong? How can I prove this on an IList<T>? Is this a bug in the static analyzer? How would I submit a bug report to Microsoft?

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• Building an XML editor in java and RichFaces

  - by Mark Lewis

  Hello I'm building an XML editor using the above technologies. In essence, I want to read in a whole XML file to a java object, and refer using this object to each element in the XML node tree (grouped into entries) to display the content locked, have separate padlocks for the user to click to 'unlock' an entry allow overwriting of the data, and to submit this entry. 'Add entry', 'Duplicate entry', 'Delete entry' are also functions I'd like to add. I already use dom4j and XPath to access areas of the XML file so some of the work in theory is already done. Given the above, I was going to use these two together with inplaceInputs to allow the user to edit the XML and JSF validators to check the data coming in. Is this the best way to approach this problem, or is there a more straightforward route than XPathing a whole record? I started looking at jaxb but I'm new at java and jsf but I've got the feeling I won't be by the end.. Thanks

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• Good example usage of get_or _create in Django views and raising a Form error

  - by Rik Wade

  I would like to use get_or_create to check whether an object already exists in my database. If it does not, then it will be created. If it does exist, then I will not create the new object, but need to raise a form error to inform the user that they need to enter different data (for example, a different username). The view contains: p, created = Person.objects.get_or_create( email = registration_form.cleaned_data['email'], defaults = { 'creationDate': datetime.datetime.now(), 'dateOfBirth': datetime.date(1970,1,1) }) So 'p' will contain the existing Person if it exists, or the new Person if not. I would like to act on the boolean value in 'created' in order to skip over saving the Person and re-display the registration_form and raise an appropriate form validation error. The alternative I'm considering is doing a check in a custom Form validation method to see whether a Person exists with the data in the provided 'email' field, and just raising a validation error.

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• How to make the subview in a UIScrollView to refresh when we zoom it?

  - by wolverine

  I have subclassed UIView object inside a uiscrollview which displays a pdf page. I can zoom that page. But when I do so, the inside view is zoomed and is getting blurred. I understood that the inner view shud be refreshed and i called setNeedsDisplay. But no change have happened and its the same even now. Below is the code for drawRect for the subclassed uiview. - (void)drawRect:(CGRect)rect { if(document)//the pdf document object { CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextSaveGState(ctx); CGContextTranslateCTM(ctx, 0.00, [self bounds].size.height); NSLog(@"%f",[self bounds].size.height); CGContextScaleCTM(ctx, 1.0, -1.0); CGContextConcatCTM(ctx, CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, [self bounds], 0, true)); CGContextDrawPDFPage(ctx, page); CGContextRestoreGState(ctx); } }

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• WPF -- Event Threading, GUI updating question

  - by LSTayon

  I'm trying to send two events to the main window so that I can show some kind of animation that will let the user know that I'm updating the data. This is an ObservableCollection object so the OnPropertyChanged is immediately picked up by the bindings on the main window. The sleep is only in there so that the user can see the animation. However, the first OnPropetyChanged is never seen. I'm assuming this is because we're in a single thread here and the timer_Tick has to finish before the GUI updates. Any suggetions? In VB6 land we would use a DoEvents or a Form.Refresh. Thanks! private void timer_Tick(object sender, EventArgs e) { Loading = "Before: " + DateTime.Now.ToString(); OnPropertyChanged("Loading"); LoadData(); Thread.Sleep(1000); //Loading = Visibility.Hidden; Loading = "After: " + DateTime.Now.ToString(); OnPropertyChanged("Loading"); }

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• client ip address in ASP.NET (.asmx) webservices

  - by Zain Shaikh

  I am using ASP.Net (.asmx) web services with Silverlight. since there is no way to find client ip address in Silverlight, therefore I had to log this on service end. these are some methods I have tried: Request.ServerVariables(”REMOTE_HOST”) HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"] HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; Request.UserHostAddress() Request.UserHostName() string strHostName = System.Net.Dns.GetHostName(); string clientIPAddress = System.Net.Dns.GetHostAddresses(strHostName).GetValue(0).ToString(); All the above methods work fine on my local system, but when I publish my service on production server. it starts giving errors. Error: Object reference not set to an instance of an object. StackTrace: at System.Web.Hosting.ISAPIWorkerRequestInProc.GetAdditionalServerVar(Int32 index) at System.Web.Hosting.ISAPIWorkerRequestInProc.GetServerVariable(String name) at System.Web.Hosting.ISAPIWorkerRequest.GetRemoteAddress() at System.Web.HttpRequest.get_UserHostAddress()

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