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  • How to design a game engine in an object-oriented language?

    - by chuzzum
    Whenever I try and write a game in any object-oriented language, the first problem I always face (after thinking about what kind of game to write) is how to design the engine. Even if I'm using existing libraries or frameworks like SDL, I still find myself having to make certain decisions for every game, like whether to use a state machine to manage menus, what kind of class to use for resource loading, etc. What is a good design and how would it be implemented? What are some tradeoffs that have to be made and their pros/cons?

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  • How to model the components of a non Information System?

    - by Adel C Kod
    So I am working on a project that's related to the Kernel code(specifically related to the TCP/IP stack of the kernel). I need to build some models to describe the functionality and components of my system. Initially I thought about Class Diagram, it can describe the general architecture of my system but it doesn't make sense since my code is VERY structured(written in standard C). I also thought about DFDs, they'd describe the processes of my system, and how the data is flowing. But they contain something which doesn't really fit in; data-storages. I have no databases here(at all). For the functionality, other team members suggested using Activity and Sequence diagrams, which is kinda okay with me, but what about the system components? So basically my question is; I want to describe the components of my system; what do you suggest as a meaningful diagram to follow? (Again, the project is a research low-level systems-oriented project with almost no user-interface at all)

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  • How should I model an economy-based game in code?

    - by Matthew G.
    I'd like to create an economy game based on an ancient civilization. I'm not sure how to design it. If I were working on a smaller game, like a copy of "Space Invaders," I'd have no problem structuring it like this: Main Control Class Graphics Class Player Class Enemy class I don't understand how I'd do this for larger projects like my economy game. Do I create a country class that contains a bunch of towns? Do the towns contain a lot building class, most contain classes of people? Do I make a path finding class that the player can access to get around?

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  • Entity Framework 5, separating business logic from model - Repository?

    - by bnice7
    I am working on my first public-facing web application and I’m using MVC 4 for the presentation layer and EF 5 for the DAL. The database structure is locked, and there are moderate differences between how the user inputs data and how the database itself gets populated. I have done a ton of reading on the repository pattern (which I have never used) but most of my research is pushing me away from using it since it supposedly creates an unnecessary level of abstraction for the latest versions of EF since repositories and unit-of-work are already built-in. My initial approach is to simply create a separate set of classes for my business objects in the BLL that can act as an intermediary between my Controllers and the DAL. Here’s an example class: public class MyBuilding { public int Id { get; private set; } public string Name { get; set; } public string Notes { get; set; } private readonly Entities _context = new Entities(); // Is this thread safe? private static readonly int UserId = WebSecurity.GetCurrentUser().UserId; public IEnumerable<MyBuilding> GetList() { IEnumerable<MyBuilding> buildingList = from p in _context.BuildingInfo where p.Building.UserProfile.UserId == UserId select new MyBuilding {Id = p.BuildingId, Name = p.BuildingName, Notes = p.Building.Notes}; return buildingList; } public void Create() { var b = new Building {UserId = UserId, Notes = this.Notes}; _context.Building.Add(b); _context.SaveChanges(); // Set the building ID this.Id = b.BuildingId; // Seed 1-to-1 tables with reference the new building _context.BuildingInfo.Add(new BuildingInfo {Building = b}); _context.GeneralInfo.Add(new GeneralInfo {Building = b}); _context.LocationInfo.Add(new LocationInfo {Building = b}); _context.SaveChanges(); } public static MyBuilding Find(int id) { using (var context = new Entities()) // Is this OK to do in a static method? { var b = context.Building.FirstOrDefault(p => p.BuildingId == id && p.UserId == UserId); if (b == null) throw new Exception("Error: Building not found or user does not have access."); return new MyBuilding {Id = b.BuildingId, Name = b.BuildingInfo.BuildingName, Notes = b.Notes}; } } } My primary concern: Is the way I am instantiating my DbContext as a private property thread-safe, and is it safe to have a static method that instantiates a separate DbContext? Or am I approaching this all wrong? I am not opposed to learning up on the repository pattern if I am taking the total wrong approach here.

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  • Basic modelling of radar

    - by Hawk66
    I'm currently researching how to model/simulate radar for my naval simulation. Since the emphasis is on modelling ASW or submarines in general, I need only a basic radar model - at least for the beginning. So, does anybody know a resource for such a simple model? The model should take signal strength of the sensor, the size of the target and the terrain (height/ground clutter) into account. Thanks.

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  • How do you know when to split an object method into 2 or more other methods?

    - by blacktie24
    Hi, I know this is a very basic question, but I sometimes find myself struggling to figure out when to split a single object method into multiple methods. For example, I am trying to set up an ACL using Zend_Acl and Zend_Auth, as shown in this tutorial: http://devzone.zend.com/article/1665. However, I am wondering if the My_Plugin_Auth::preDispatch() method should invoke calls to a method called authenticate() and a method called authorize(), instead of having everything lumped in under preDispatch(). I was thinking that this would make the code more readable and encapsulate the logic into its smaller parts, but i'm not sure if this is reason enough.

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  • How can I explain object-oriented programming to someone who's only coded in Fortran 77? [closed]

    - by Zonedabone
    Possible Duplicate: How can I explain object-oriented programming to someone who’s only coded in Fortran 77? My mother did her college thesis in Fortran, and now (over a decade later) needs to learn c++ for fluids simulations. She is able to understand all of the procedural programming, but no matter how hard I try to explain objects to her, it doesn't stick. (I do a lot of work with Java, so I know how objects work) I think I might be explaining it in too high-level ways, so it isn't really making sense to someone who's never worked with them at all and grew up in the age of purely functional programming. Is there any simple way I can explain them to her that will help her understand? Thanks for the help in advance.

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  • What's a good model for continuous manager <-> programmer feedback?

    - by MebAlone
    Is it important for managers to give devs regular feedback on how they're doing and vice versa? I say vice versa because I consider employees to be responsible to their manager, and managers to be responsible to their employees. Everyone seems to think this is a good idea but in practice I rarely see it happen because so many shops are "agile" now and that usually means a daily standup plus a weekly kickoff, etc. So one-on-ones just don't happen. In my last position I had my first one-on-one w/ my manager 6 months after I'd been w/ the company. It turned out there was lots of misunderstanding, misalignment and confusion built up and snowballed. Not really surprising when there's no direct personal communication for that long.

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  • ASP.NET 4.0 and the Entity Framework 4 - Part 1 - Create a Database using Model-First Development

    This is the first in a series of articles that will develop an ASP.NET application that uses the Entity Framework 4. This article will demonstrate how to use Visual Studio 2010 and the Entity Framework 4 to create a database in a step-by-step approach. The database created in this article will then be used in future articles to demonstrate how to add, update, delete, and select records using the Entity Framework.

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  • What's the importance of restoring SQL Server system databases (model, master, etc.)?

    - by Zero Subnet
    I had to restore some production databases to a different drive on the same Microsoft SQL Server 2005 machine. That worked fine and the application using the databases is back online. However, i have not restored the system (or default?) databases that SQL Server creates on its own (model, master, etc.). My question is, what is the role of these databases? and how important it is that i restore them?

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  • How do I fix the audio on my laptop. model Fujitsu B6220

    - by user89756
    I reinstalled Ubuntu 12.04 on my laptop because the Unity desktop was freezing. Reinstalling 12.04 seems to have fixed the freezing problem, but now the audio does not work. When I go to SettingsAudio and under the Output tab it only has the option for Digital Output. There is no option for Analog Output. The sound card show up under lspci as: "00:1b.0 Audio device: Intel Corporation N10/ICH 7 Family High Definition Audio Controller (rev 02)" What would be the command to reinstall the audio subsystem? If that would fix it...

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  • Mimicking Network Databases in SQL

    Unlike the hierarchical database model, which created a tree structure in which to store data, the network model formed a generalized 'graph' structure that describes the relationships between the nodes. Nowadays, the relational model is used to solve the problems for which the network model was created, but the old 'network' solutions are still being implemented by programmers, even when they are less effective.

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  • Multiplayer in a game. How to design it object wise?

    - by Ninetou
    I was suggested on StackOverflow to ask this question here. I'm working on a simple game and I was thinking of adding multiplayer feature but I'm a bit stuck. I'm not sure what approach should I take, keeping in mind good programming practices. I have a Player object which is created for each player but then I have many other classes that would have to be able to access them. The thing is, if I initialise them in, let's say my main method, then I can't relate to different instances of player class from other classes. The only solution to my problem that comes to my mind is using some form of global objects but afaik using anything globally in apps is usually not a good practice. Any suggestions/ideas?

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  • Difficult to replicate objects (object Customer) on the list? [migrated]

    - by gandolf
    I wrote a program that does work with files like delete and update, store, and search And all customers But I have a problem with the method is LoadAll Once the data are read from the file and then Deserialize the object becomes But when I want to save the list of objects in the list are repeated. How can I prevent the duplication in this code? var customerStr = File.ReadAllLines (address); The code is written in CustomerDataAccess class DataAccess Layer. Project File The main problem with the method LoadAll Code: public ICollection<Customer> LoadAll() { var alldata = File.ReadAllLines(address); List<Customer> lst = new List<Customer>(); foreach (var s in alldata) { var objCustomer = customerSerializer.Deserialize(s); lst.Add(objCustomer); } return lst; }

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  • Call Webservice without adding a WebReference - with Complex Types

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

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  • xamlparser error after clickonce deployment.Application crashing after installation

    - by black sensei
    Hello Good People, I've built an WPF application with visual studio 2008 and created an installer for it.Works fine so far.I realized it lacks the automatic updates feature, and after trying several solutions, i decided to give a try to clickonce deployment.After a successful deployment on a network server, i 've noticed that the application crashes after installation of the downloaded app.It complains about this: Cannot create instance of 'Login' defined in assembly 'MyApplication, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. Exception has been thrown by the target of an invocation. Error in markup file 'MyApplication;component/login.xaml' Line 1 Position 9. here is the stacktrace at System.Windows.Markup.XamlParseException.ThrowException(String message, Exception innerException, Int32 lineNumber, Int32 linePosition, Uri baseUri, XamlObjectIds currentXamlObjectIds, XamlObjectIds contextXamlObjectIds, Type objectType) at System.Windows.Markup.XamlParseException.ThrowException(ParserContext parserContext, Int32 lineNumber, Int32 linePosition, String message, Exception innerException) at System.Windows.Markup.BamlRecordReader.ThrowExceptionWithLine(String message, Exception innerException) at System.Windows.Markup.BamlRecordReader.CreateInstanceFromType(Type type, Int16 typeId, Boolean throwOnFail) at System.Windows.Markup.BamlRecordReader.GetElementAndFlags(BamlElementStartRecord bamlElementStartRecord, Object& element, ReaderFlags& flags, Type& delayCreatedType, Int16& delayCreatedTypeId) at System.Windows.Markup.BamlRecordReader.BaseReadElementStartRecord(BamlElementStartRecord bamlElementRecord) at System.Windows.Markup.BamlRecordReader.ReadElementStartRecord(BamlElementStartRecord bamlElementRecord) at System.Windows.Markup.BamlRecordReader.ReadRecord(BamlRecord bamlRecord) at System.Windows.Markup.BamlRecordReader.Read(Boolean singleRecord) at System.Windows.Markup.TreeBuilderBamlTranslator.ParseFragment() at System.Windows.Markup.TreeBuilder.Parse() at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream) at System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc) at System.Windows.Application.LoadComponent(Uri resourceLocator, Boolean bSkipJournaledProperties) at System.Windows.Application.DoStartup() at System.Windows.Application.<.ctorb__0(Object unused) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at myApplication.App.Main() here is just the region the debugger is pointing to <Window x:Class="MyApplication.Login" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:MyApplication" xmlns:UI="clr-namespace:UI;assembly=UI" Title="My Application" Height="400" Width="550" ResizeMode="NoResize" WindowStyle="ThreeDBorderWindow" WindowStartupLocation="CenterScreen" Name="Logine" Loaded="Logine_Loaded" Closed="Logine_Closed" Icon="orLogo.ico"> But the installer version as in the msi from setup project works fine.so i cannot see where the error is comming from since i can have design view. Question 1 : Does any one have a similar issue, or is that a known issue? Question 2 : If it's a known issue then what are alternative.I might give up on the clickonce but then i my automatic update feature will be lost (as in there is none which is not ovekill or seriously outdated that i can find right now). thanks for reading this and for pointing me to the right direction.

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  • ObjectContext.SaveChanges() fails with SQL CE

    - by David Veeneman
    I am creating a model-first Entity Framework 4 app that uses SQL CE as its data store. All is well until I call ObjectContext.SaveChanges() to save changes to the entities in the model. At that point, SaveChanges() throws a System.Data.UpdateException, with an inner exception message that reads as follows: Server-generated keys and server-generated values are not supported by SQL Server Compact. I am completely puzzled by this message. Any idea what is going on and how to fix it? Thanks. Here is the Exception dump: System.Data.UpdateException was unhandled Message=An error occurred while updating the entries. See the inner exception for details. Source=System.Data.Entity StackTrace: at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache) at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) at System.Data.Objects.ObjectContext.SaveChanges() at FsDocumentationBuilder.ViewModel.Commands.SaveFileCommand.Execute(Object parameter) in D:\Users\dcveeneman\Documents\Visual Studio 2010\Projects\FsDocumentationBuilder\FsDocumentationBuilder\ViewModel\Commands\SaveFileCommand.cs:line 68 at MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated) at System.Windows.Controls.Primitives.ButtonBase.OnClick() at System.Windows.Controls.Button.OnClick() at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e) at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e) at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent) at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e) at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args) at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted) at System.Windows.Input.InputManager.ProcessStagingArea() at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport) at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel) at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at FsDocumentationBuilder.App.Main() in D:\Users\dcveeneman\Documents\Visual Studio 2010\Projects\FsDocumentationBuilder\FsDocumentationBuilder\obj\x86\Debug\App.g.cs:line 50 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: System.Data.EntityCommandCompilationException Message=An error occurred while preparing the command definition. See the inner exception for details. Source=System.Data.Entity StackTrace: at System.Data.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree commandTree) at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.CreateCommand(UpdateTranslator translator, Dictionary`2 identifierValues) at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.Execute(UpdateTranslator translator, EntityConnection connection, Dictionary`2 identifierValues, List`1 generatedValues) at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) InnerException: System.NotSupportedException Message=Server-generated keys and server-generated values are not supported by SQL Server Compact. Source=System.Data.SqlServerCe.Entity StackTrace: at System.Data.SqlServerCe.SqlGen.DmlSqlGenerator.GenerateReturningSql(StringBuilder commandText, DbModificationCommandTree tree, ExpressionTranslator translator, DbExpression returning) at System.Data.SqlServerCe.SqlGen.DmlSqlGenerator.GenerateInsertSql(DbInsertCommandTree tree, List`1& parameters, Boolean isLocalProvider) at System.Data.SqlServerCe.SqlGen.SqlGenerator.GenerateSql(DbCommandTree tree, List`1& parameters, CommandType& commandType, Boolean isLocalProvider) at System.Data.SqlServerCe.SqlCeProviderServices.CreateCommand(DbProviderManifest providerManifest, DbCommandTree commandTree) at System.Data.SqlServerCe.SqlCeProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree) at System.Data.Common.DbProviderServices.CreateCommandDefinition(DbCommandTree commandTree) at System.Data.Common.DbProviderServices.CreateCommand(DbCommandTree commandTree) at System.Data.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree commandTree) InnerException:

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  • Survey Data Model - How to avoid EAV and excessive denormalization?

    - by AlexDPC
    Hi everyone, My database skills are mediocre at best and I have to design a data model for survey data. I have spent some thoughts on this and right now I feel that I am stuck between some kind of EAV model and a design involving hundreds of tables, each with hundreds of columns (and thousands of records). There must be a better way to do this and I hope that the wise folks on this forum can help me. I have already searched various forums, but I couldn't really find a solution. If it has already been given elsewhere, please excuse me and provide me with a link so I can read it up. Some assumptions about the data I have to deal with: Each survey consists of 1 to n questionnaires Each questionnaire consists of 100-2,000 questions (please ignore that 2,000 questions really sound like a lot to answer...) Questions can be of various types: multiple-choice, free text, a number (like age, income, percentages, ...) Each survey involves 10-200 countries (These are not the respondents. The respondents are actually people in the countries.) Depending on the type of questionnaire, each questionnaire is answered by 100-20,000 respondents per country. A country can adapt the questionnaires for a survey, i.e. add, remove or edit questions The data for one country is gathered in a separate database in that country. There is no possibility for online integration from the start. The data for all countries has to be integrated later. This means for example, if a country has deleted a question, that data must somehow be derived from what they sent in order to achieve a uniform design across all countries I will have to write the integration and cleaning software, which will need to work with every country's data In the end the data needs to be exported to flat files, one rectangular grid per country and questionnaire. I have already discussed this topic with people from various backgrounds and have not come to a good solution yet. I mainly got two kinds of opinions. The domain experts, who are used to working with flat files (spreadsheet-style) for data processing and analysis vote for a denormalized structure with loads of tables and columns as I described above (1 table per country and questionnaire). This sounds terrible to me, because I learned that wide tables are to be avoided, it will be annoying to determine which columns are actually in a table when working with it, the database will become cluttered with hundreds of tables (or I even need to set up multiple databases, each with a similar yet a bit differetn design), etc. O-O-programmers vote for a strongly "normalized" design, which would effectively lead to a central table containing all the answers from all respondents to all questions. This table would either need to contain a column of type sql_variant type or multiple answer columns with different types to store answers of different types (multiple choice, free text, ..). The former would essentially be a EAV model. I tend to follow Joe Celko here, who strongly discourages its use (he calls it OTLT or "One True Lookup Table"). The latter would imply that each row would contain null cells for the not applicable types by design. Another alternative I could think of would be to create one table per answer type, i.e., one for multiple-choice questions, one for free text questions, etc.. That's not so generic, it would lead to a lot of union joins, I think and I would have to add a table if a new answer type is invented. Sorry for boring you with all this text and thank you for your input! Cheers, Alex PS: I asked the same question here: http://www.eggheadcafe.com/community/aspnet/13/10242616/survey-data-model--how-to-avoid-eav-and-excessive-denormalization.aspx

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  • Another design-related C++ question

    - by Kotti
    Hi! I am trying to find some optimal solutions in C++ coding patterns, and this is one of my game engine - related questions. Take a look at the game object declaration (I removed almost everything, that has no connection with the question). // Abstract representation of a game object class Object : public Entity, IRenderable, ISerializable { // Object parameters // Other not really important stuff public: // @note Rendering template will never change while // the object 'lives' Object(RenderTemplate& render_template, /* params */) : /*...*/ { } private: // Object rendering template RenderTemplate render_template; public: /** * Default object render method * Draws rendering template data at (X, Y) with (Width, Height) dimensions * * @note If no appropriate rendering method overload is specified * for any derived class, this method is called * * @param Backend & b * @return void * @see */ virtual void Render(Backend& backend) const { // Render sprite from object's // rendering template structure backend.RenderFromTemplate( render_template, x, y, width, height ); } }; Here is also the IRenderable interface declaration: // Objects that can be rendered interface IRenderable { /** * Abstract method to render current object * * @param Backend & b * @return void * @see */ virtual void Render(Backend& b) const = 0; } and a sample of a real object that is derived from Object (with severe simplifications :) // Ball object class Ball : public Object { // Ball params public: virtual void Render(Backend& b) const { b.RenderEllipse(/*params*/); } }; What I wanted to get is the ability to have some sort of standard function, that would draw sprite for an object (this is Object::Render) if there is no appropriate overload. So, one can have objects without Render(...) method, and if you try to render them, this default sprite-rendering stuff is invoked. And, one can have specialized objects, that define their own way of being rendered. I think, this way of doing things is quite good, but what I can't figure out - is there any way to split the objects' "normal" methods (like Resize(...) or Rotate(...)) implementation from their rendering implementation? Because if everything is done the way described earlier, a common .cpp file, that implements any type of object would generally mix the Resize(...), etc methods implementation and this virtual Render(...) method and this seems to be a mess. I actually want to have rendering procedures for the objects in one place and their "logic implementation" - in another. Is there a way this can be done (maybe alternative pattern or trick or hint) or this is where all this polymorphic and virtual stuff sucks in terms of code placement?

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  • Linked List Design

    - by Jim Scott
    The other day in a local .NET group I attend the following question came up: "Is it a valid interview question to ask about Linked Lists when hiring someone for a .NET development position?" Not having a computer sciense degree and being a self taught developer my response was that I did not feel it was appropriate as I in 5 years of developer with .NET had never been exposed to linked lists and did not hear any compeling reason for a use for one. However the person commented that it is a very common interview question so I decided when I left that I would do some reasearch on linked lists and see what I might be missing. I have read a number of posts on stack overflow and various google searches and decided the best way to learn about them was to write my own .NET classes to see how they worked from the inside out. Here is my class structure Single Linked List Constructor public SingleLinkedList(object value) Public Properties public bool IsTail public bool IsHead public object Value public int Index public int Count private fields not exposed to a property private SingleNode firstNode; private SingleNode lastNode; private SingleNode currentNode; Methods public void MoveToFirst() public void MoveToLast() public void Next() public void MoveTo(int index) public void Add(object value) public void InsertAt(int index, object value) public void Remove(object value) public void RemoveAt(int index) Questions I have: What are typical methods you would expect in a linked list? What is typical behaviour when adding new records? For example if I have 4 nodes and I am currently positioned in the second node and perform Add() should it be added after or before the current node? Or should it be added to the end of the list? Some of the designs I have seen explaining things seem to expose outside of the LinkedList class the Node object. In my design you simply add, get, remove values and know nothing about any node object. Should the Head and Tail be placeholder objects that are only used to define the head/tail of the list? I require my Linked List be instantiated with a value which creates the first node of the list which is essentially the head and tail of the list. Would you change that ? What should the rules be when it comes to removing nodes. Should someone be able to remove all nodes? Here is my Double Linked List Constructor public DoubleLinkedList(object value) Properties public bool IsHead public bool IsTail public object Value public int Index public int Count Private fields not exposed via property private DoubleNode currentNode; Methods public void AddFirst(object value) public void AddLast(object value) public void AddBefore(object existingValue, object value) public void AddAfter(object existingValue, object value) public void Add(int index, object value) public void Add(object value) public void Remove(int index) public void Next() public void Previous() public void MoveTo(int index)

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  • I can't Open my excel file in c#

    - by Ruben Guico
    Hi, Below is my code, i tried to open my excel file in my c# application but the program give's me an error message "Cannot Access "my excel.xls". But when I specify the file path in my string path variable it works, the problem is I need to get the file path from an openFileDialog. using System; using System.IO; using System.Collections.Generic; using System.Text; using System.Data; using System.Windows.Forms; using System.Data.OleDb; using System.Reflection; using MOIE = Microsoft.Office.Interop.Excel; using OFFICE = Microsoft.Office.Core; namespace EmpUploader { public class ExcelCon { private OleDbDataReader reader = null; private OleDbCommand excelCommand = new OleDbCommand(); private OleDbDataAdapter adapter = new OleDbDataAdapter(); private DataTable excelData = new DataTable(); private MOIE.ApplicationClass objExcel = new MOIE.ApplicationClass(); private MOIE.Workbook wb = null; private string myConn = ""; private string strSQL = ""; private string err = ""; private string path2 = ""; private int sheetCount = 0; private OleDbConnection Con = new OleDbConnection(""); #region "excel interop prarameters" private static object xl_missing = Type.Missing; private static object xl_true = true; private static object xl_false = false; private object xl_update_links = xl_missing; private object xl_read_only = xl_missing; private object xl_format = xl_missing; private object xl_password = xl_missing; private object xl_write_res_password = xl_missing; private object xl_ignore_read_only = xl_missing; private object xl_origin = xl_missing; private object xl_delimiter = xl_missing; private object xl_editable = xl_missing; private object xl_notify = xl_missing; private object xl_converter = xl_missing; private object xl_add_to_mru = xl_missing; private object xl_local = xl_missing; private object xl_corrupt_load = xl_missing; #endregion } //MY CODE FOR OPENING THE EXCEL //note that my file path came from an openfiledialog public void InitializeConnection(string path) { //connection string for excel myConn = @"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + path + "; Extended Properties =Excel 8.0"; Con.ConnectionString = myConn; Con.Open(); //this is the sample specified path that worked when i test my application //path = @"C:\shinetsu p5 emp list.xls"; objExcel.Visible = false; wb = objExcel.Workbooks.Open(path, xl_update_links, xl_read_only, xl_format, xl_password, xl_write_res_password, xl_ignore_read_only, xl_origin, xl_delimiter, xl_editable, xl_notify, xl_converter, xl_add_to_mru, xl_local, xl_corrupt_load); sheetCount = wb.Worksheets.Count; } }

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  • Spring's EntityManager not persisting

    - by Fernando Camargo
    Well, my project was using EJB and JPA (with Hibernate), but I had to switch to Spring. Everything was working well before that. The EJB used to inject the EntityManager, controled the transaction, etc. Ok, when I switched to Spring, I had a lot of problems because I'm new on Spring. But after everything is running, I have the problem: the data is never saved on database. I configured my Spring to control the transactions, I have spring beans used in JSF, that has spring services that do the hard work. This services have a EntityManager injected and use @Transactional REQUIRED. This services pass the EntityManager to a DAO that call entityManager.persist(bean). The selects appears to work well, the JTA transaction appears to work well to (I saw in log), but the entity is not saved! Here is the log: INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter: doFilterInternal() (linha 136): Opening JPA EntityManager in OpenEntityManagerInViewFilter INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory: doGetBean() (linha 245): Returning cached instance of singleton bean 'transactionManager' INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: getTransaction() (linha 365): Creating new transaction with name [br.org.cni.pronatec.controller.service.MontanteServiceImpl.adicionarValor]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT; '' INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doBegin() (linha 493): Opened new Session [org.hibernate.impl.SessionImpl@2b2fe2f0] for Hibernate transaction INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doBegin() (linha 504): Preparing JDBC Connection of Hibernate Session [org.hibernate.impl.SessionImpl@2b2fe2f0] INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doBegin() (linha 569): Exposing Hibernate transaction as JDBC transaction [com.sun.gjc.spi.jdbc40.ConnectionHolder40@3bcd4840] INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler: doJoinTransaction() (linha 383): Joined JTA transaction INFO: Hibernate: select hibernate_sequence.nextval from dual INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: processCommit() (linha 752): Initiating transaction commit INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doCommit() (linha 652): Committing Hibernate transaction on Session [org.hibernate.impl.SessionImpl@2b2fe2f0] INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doCleanupAfterCompletion() (linha 734): Closing Hibernate Session [org.hibernate.impl.SessionImpl@2b2fe2f0] after transaction INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.SessionFactoryUtils: closeSession() (linha 800): Closing Hibernate Session INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter: doFilterInternal() (linha 154): Closing JPA EntityManager in OpenEntityManagerInViewFilter INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.EntityManagerFactoryUtils: closeEntityManager() (linha 343): Closing JPA EntityManager In the log, I see it commiting the transaction, but I don't see the insert query (the Hibernate is printing any query). I also see that the Hibernate lookup to get the next value of the sequence ID. But after that, it never really inserts. Here is the spring context configuration: <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="PronatecPU" /> <property name="persistenceXmlLocation" value="classpath:META-INF/persistence.xml" /> <property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver"/> </property> <property name="jpaProperties"> <props> <prop key="hibernate.transaction.factory_class">org.hibernate.transaction.JTATransactionFactory</prop> </props> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" > <property name="transactionManagerName" value="java:/TransactionManager" /> <property name="userTransactionName" value="UserTransaction" /> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> <tx:annotation-driven transaction-manager="transactionManager" /> Here is my persistence.xml: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="PronatecPU" transaction-type="JTA"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>jdbc/pronatec</jta-data-source> <class>br.org.cni.pronatec.model.bean.AgendamentoBuscaSistec</class> <class>br.org.cni.pronatec.model.bean.AgendamentoExportacaoZeus</class> <class>br.org.cni.pronatec.model.bean.AgendamentoImportacaoZeus</class> <class>br.org.cni.pronatec.model.bean.Aluno</class> <class>br.org.cni.pronatec.model.bean.Curso</class> <class>br.org.cni.pronatec.model.bean.DepartamentoRegional</class> <class>br.org.cni.pronatec.model.bean.Dof</class> <class>br.org.cni.pronatec.model.bean.Escola</class> <class>br.org.cni.pronatec.model.bean.Inconsistencia</class> <class>br.org.cni.pronatec.model.bean.Matricula</class> <class>br.org.cni.pronatec.model.bean.Montante</class> <class>br.org.cni.pronatec.model.bean.ParametrosVingentes</class> <class>br.org.cni.pronatec.model.bean.TipoCurso</class> <class>br.org.cni.pronatec.model.bean.Turma</class> <class>br.org.cni.pronatec.model.bean.UnidadeFederativa</class> <class>br.org.cni.pronatec.model.bean.ValorAssistenciaEstudantil</class> <class>br.org.cni.pronatec.model.bean.ValorHora</class> <exclude-unlisted-classes>true</exclude-unlisted-classes> <properties> <property name="current_session_context_class" value="thread"/> <property name="hibernate.show_sql" value="true"/> <property name="hibernate.format_sql" value="true"/> <property name="hibernate.dialect" value="org.hibernate.dialect.OracleDialect"/> <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.SunONETransactionManagerLookup"/> <property name="hibernate.hbm2ddl.auto" value="update"/> </properties> </persistence-unit> </persistence> Here is my service that is injected in the managed bean: @Service @Scope("prototype") @Transactional(propagation= Propagation.REQUIRED) public class MontanteServiceImpl { // more code @PersistenceContext(unitName="PronatecPU", type= PersistenceContextType.EXTENDED) private EntityManager entityManager; // more code // The method that is called by another public method that do something before private void salvarMontante(Montante montante) { montante.setDataTransacao(new Date()); MontanteDao montanteDao = new MontanteDao(entityManager); montanteDao.salvar(montante); } // more code } My MontanteDao inherits from a base DAO, like this: public class MontanteDao extends BaseDao<Montante> { public MontanteDao(EntityManager entityManager) { super(entityManager); } } And the method that is called in BaseDao is this: public void salvar(T bean) { entityManager.persist(bean); } Like you can see, it just pick the injected entityManager and call the persist() method. The transaction is being controlled by the Spring, like is printed in the log, but the insert query is never printed in log and it is never saved. I'm sorry about my bad english. Thanks in advance for who helps.

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