MVC3 - Server Error in '/' Application. The resource cannot be found.

Problem:

MVC3 – You added your HttpPost method in your Controller, and you get:

Server Error in '/' Application.

---

The resource cannot be found.

Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly. 

Requested URL: /Movies/Edit/1

Code:

        [HttpPost]

        public ActionResult Edit(Movie model)

        {

            try

            {

                var movie = db.Movies.Find(model.ID);

                UpdateModel(movie);

                db.SaveChanges();

                return RedirectToAction("Details", new {id=model.ID});

            }

            catch (Exception)

            {

                ModelState.AddModelError("", "Edit Failure, see inner exception");

            }

            return View(model);

        }

Solution:

You forgot to add the Get method to the Controller class:

Code:

        public ActionResult Edit(int id)

        {

            var movie = db.Movies.Find(id);

            if (movie == null)

                RedirectToAction("Index");

           

            return View(movie);

        }

SqlServer: Saving changes is not permitted. The changes you have made require the followign tables to be dropped and re-created

Problem:

Saving changes is not permitted.  The changes you have made require the following tables to be dropped and re-created.  You have either made changes to a table that can’t be re-created or enabled the option Prevent saving changes that require the table to be re-created.

Solution:

This is different than the default in Sql Server 2005, where you can automatically drop and recreate a table in the designer.  Solution is simple, and doesn't require you to lose your changes.

Screenshots:

In Sql Server Management Studio 2008, go to tools à options, in the options window, left pane Designers, and on the right side uncheck Prevent saving changes that require table re-creation.

System.InvalidOperationException was unhandled by user code The model backing the 'SomeContext' context has changed since the database was created

Problem:
Received the following exception when adding a field to an Entity class:

System.InvalidOperationException was unhandled by user code

  Message=The model backing the 'MovieDBContext' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance. For example, the DropCreateDatabaseIfModelChanges strategy will automatically delete and recreate the database, and optionally seed it with new data.

  Source=EntityFramework

Full Stack Trace at the end.

Code the exception occurred:

        MovieDBContext db = new MovieDBContext();

        public ActionResult Index()

        {

            var movies = from m in db.Movies

                         where m.ReleaseDate > new DateTime(1984, 6, 1)

                         select m;

            return View(movies.ToList());

        }

Solution:

Update the table in Sql Server to have the additional column you added to your entitiy class.

Full Stack Trace:

  StackTrace:

       at System.Data.Entity.Database.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context)

       at System.Data.Entity.Database.DbDatabase.<>c__DisplayClass8.b__5()

       at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)

       at System.Data.Entity.Database.DbDatabase.Initialize(Boolean force)

       at System.Data.Entity.Internal.InternalContext.Initialize()

       at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)

       at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()

       at System.Data.Entity.Internal.Linq.InternalSet`1.get_Provider()

       at System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider()

       at System.Linq.Queryable.Where[TSource](IQueryable`1 source, Expression`1 predicate)

       at MvcMovie.Controllers.MoviesController.Index() in xxxx\visual studio 2010\Projects\MovieApp\MvcMovie\Controllers\MoviesController.cs:line 16

       at lambda_method(Closure , ControllerBase , Object[] )

       at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)

       at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)

       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)

       at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.b__12()

       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)

System.ServiceModel.CommunicationException was unhandled Exception

Problem:

Message=The underlying connection was closed: The connection was closed unexpectedly.

I was making a WCF client/service, I ran it for the first time and got that exception.  So, my WCF service had an OperationContract to return a DataTable like so:

[ServiceContract]
    public interface IUserService
    {
        [OperationContract]
        DataTable GetApprovedUser();
    }

And it was implemented like this:

public DataTable GetApprovedUser()
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("UserId", typeof (Int64));
            dt.Columns.Add("IsApproved", typeof (bool));

            DataRow newUser = dt.NewRow();
            newUser["UserId"] = 1000;
            newUser["IsApproved"] = true;
            dt.Rows.Add(newUser);
            newUser = dt.NewRow();
            newUser["UserId"] = 1001;
            newUser["IsApproved"] = true;
            dt.Rows.Add(newUser);
            newUser = dt.NewRow();
            newUser["UserId"] = 1002;
            newUser["IsApproved"] = false;
            dt.Rows.Add(newUser);
            newUser = dt.NewRow();
            newUser["UserId"] = 1003;
            newUser["IsApproved"] = true;
            dt.Rows.Add(newUser);

            return dt;
        }

And my Client:

            ServiceReference1.UserServiceClient proxy = new ServiceReference1.UserServiceClient();

            string User = proxy.Authenticate("theuser", "somecrypt");

            foreach(DataRow userRow in proxy.GetApprovedUser().Tables[0].Rows)

            {

                Console.WriteLine(string.Format("User: {0}, IsApproved: ", userRow["UserId"], userRow["IsApproved"]));

            }

Solution:

Turns out that DataTables are not serializable, so I tried wrapping the DataTable in a DataSet like this:

Interface:

    [ServiceContract]

    public interface IUserService

    {

        [OperationContract]

        void DoWork();

        [OperationContract]

        string Authenticate(string userName, string aCryptKey);

        [OperationContract]

        DataSet GetApprovedUser();

    }

Implementation:

        public DataSet GetApprovedUser()

        {

            DataSet ds = new DataSet();

            DataTable dt = new DataTable();

            ds.Tables.Add(dt);

            dt.Columns.Add("UserId", typeof (Int64));

            dt.Columns.Add("IsApproved", typeof (bool));

            DataRow newUser = dt.NewRow();

            newUser["UserId"] = 1000;

            newUser["IsApproved"] = true;

            dt.Rows.Add(newUser);

            newUser = dt.NewRow();

            newUser["UserId"] = 1001;

            newUser["IsApproved"] = true;

            dt.Rows.Add(newUser);

            newUser = dt.NewRow();

            newUser["UserId"] = 1002;

            newUser["IsApproved"] = false;

            dt.Rows.Add(newUser);

            newUser = dt.NewRow();

            newUser["UserId"] = 1003;

            newUser["IsApproved"] = true;

            dt.Rows.Add(newUser);

            return ds;

        }

And that fixed it.

For those interested, here was the full stack trace:

  Message=The underlying connection was closed: The connection was closed unexpectedly.

  Source=mscorlib

  StackTrace:

    Server stack trace:

       at System.ServiceModel.Channels.HttpChannelUtilities.ProcessGetResponseWebException(WebException webException, HttpWebRequest request, HttpAbortReason abortReason)

       at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)

       at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)

       at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)

       at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)

       at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)

       at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)

    Exception rethrown at [0]:

       at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)

       at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)

       at WCRTestClient.ServiceReference1.IUserService.GetApprovedUser()

       at WCRTestClient.ServiceReference1.UserServiceClient.GetApprovedUser() in xxxx\visual studio 2010\Projects\Test WCF\WCRTestClient\Service References\ServiceReference1\Reference.cs:line 64

       at WCRTestClient.Program.Main(String[] args) in xxxx\visual studio 2010\Projects\Test WCF\WCRTestClient\Program.cs:line 15

       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.Net.WebException

       Message=The underlying connection was closed: The connection was closed unexpectedly.

       Source=System

       StackTrace:

            at System.Net.HttpWebRequest.GetResponse()

            at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)

C#: Parallel ForEach AggregateException

When working with Parallel.ForEach, you'll at some point want to handle exceptions cleanly.  I found that the AggregateException class to be very helpful.  Check out the following example to see how it works:

private static void AggregateExceptionDemo()
        {
            byte[] myData = new byte[500];
            Random r = new Random();
            r.NextBytes(myData);

            try
            {
                DoWorkInParallel(myData);
            }
            catch (AggregateException ae)
            {
                foreach (var ex in ae.InnerExceptions)
                {
                    if (ex is ArgumentException)
                        Console.WriteLine(ex.Message);
                    else
                        throw ex;
                }
            }
        }



        private static void DoWorkInParallel(byte[] myData)
        {
            // Use ConcurrentQueue to enable safe enqueueing from multiple threads.
            var exceptions = new ConcurrentQueue();

            // Execute the complete loop and capture all exceptions.
            Parallel.ForEach(myData, d =>
            {
                try
                {
                    // Cause a few exceptions, but not too many.
                    if (d < 0x3)
                        throw new ArgumentException(String.Format("value is {0:x}. Elements must be greater than 0x3.", d));
                    else
                        Console.Write(d + " ");
                }
                // Store the exception and continue with the loop.                    
                catch (Exception e) { exceptions.Enqueue(e); }
            });

            // Throw the exceptions here after the loop completes.
            if (exceptions.Count < 0) throw new AggregateException(exceptions);
        }

C#: Parallel.ForEach Simple Example

The Parallel ForEach feature of .Net 4.0 makes threading even easier.  There is no reason to not try to take advantage of today’s multi-core hardware.  Thread synchronization aside, here’s a very simple sample:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ThreadingSamples
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> numbers = new List<int>();
            for (int i = 0; i < 100; i++)
                numbers.Add(i);

            Parallel.ForEach(numbers, number =>
                {
                    Console.WriteLine(number);
                }
                );

        }
    }
}