Error using dynamic keyword in asp.net mvc 4

Question

I am getting this long error when i accpet the parameter as dynamic on my server side action method in mvc 4.

{"Message":"An error has occurred.","ExceptionMessage":"'Newtonsoft.Json.Linq.JObject' does not contain a definition for 'TournamentId'","ExceptionType":"Microsoft.CSharp.RuntimeBinder.RuntimeBinderException","StackTrace":" at CallSite.Target(Closure , CallSite , Object )\r\n at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)\r\n at ManagerDeTorneos.Web.Controllers.TournamentDateController.Create(Object data) in F:\Prince\Projects\Juan\trunk\ManagerDeTorneos.Web\Controllers\TournamentDateController.cs:line 133\r\n at lambda_method(Closure , Object , Object[] )\r\n at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c_DisplayClass13.b_c(Object instance, Object[] methodParameters)\r\n at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)\r\n at System.Threading.Tasks.TaskHelpers.RunSynchronously[TResult](Func`1 func, CancellationToken cancellationToken)"}

[HttpPost]
public HttpResponseMessage AddMatch(dynamic data)
{
    int tournamentDateId = (int)data.TournamentDateId.Value;
    var tournamentDate = Catalog.TournamentDateRepository.GetById(tournamentDateId);
    if (tournamentDate == null)
    {
        throw ExceptionHelper.NotFound("Fecha no encontrada!");
    }

In The above method data Contains tournamentId as sent from ajax call as JSON.Stringify({'TournamentId':'5'}).

Can anybody tell me what is the cause of error. I even replaced the dll of Newtonsoft.Json as well

I am not sure, but instead of dynamic, passing object as action method parameter is a good idea.. — Paritosh
– Paritosh, Commented Jun 19, 2013 at 13:04

Kapil Garg · Accepted Answer · 2013-06-24 08:45:33Z

1

You are right dan but i fixed my issue by removing that dll from GAC. May be in GAC it was using old assembly

answered Jun 24, 2013 at 8:45

Kapil Garg

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1 Comment

Sabby62 Over a year ago

This saved me alot of time. Had no clue why this error was happening but now it works fine! Thanks

Dan · Accepted Answer · 2013-06-19 13:03:02Z

The error is caused by the fact that you typed your parameter as dynamic, which means that the model binder doesn't know what to make it. It's the same as if you were to declare it as an object. Since you are providing JSON, it serializes the object as a Json.Net JObject. Just because you define it as a dynamic doesn't mean that it's going to magically take whatever shape you need it to.

Change it to a concrete type - something that matches the structure of the provided JSON:

public class TournamentInfo
{
    public int TournamentId { get; set; }
}

[HttpPost]
public HttpResponseMessage AddMatch(TournamentInfo data)
{
    int tournamentDateId = data.TournamentId;
    var tournamentDate = Catalog.TournamentDateRepository.GetById(tournamentDateId);
    if (tournamentDate == null)
    {
        throw ExceptionHelper.NotFound("Fecha no encontrada!");
    }

This way, the binder knows what it's supposed to turn the JSON into, and since TournamentInfo matches the structure of the JSON, it won't have any trouble serializing it.

Don't misuse dynamic. It was not introduced into C# so developers could stop defining classes.

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