Handling Exceptions in MVC4 when API Controller creation fails?

Question

I got an error on the creation of an api controller due to that I didn't set up autofac for webapi.

However, I can't seem to catch the exception anywhere.

<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>
Type 'MyWeb.Web.Controllers.MyController' does not have a default constructor
</ExceptionMessage>
<ExceptionType>System.ArgumentException</ExceptionType>
<StackTrace>
at System.Linq.Expressions.Expression.New(Type type) at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType) at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator) at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
</StackTrace>
</Error>

I tried adding WebApi contrib for Elmah, then I added this:

config.Filters.Add(new Elmah.Contrib.WebApi.ElmahHandleErrorApiAttribute());

Didn't make elmah register the exception. I added the following to global.asax:

protected void Application_Error(object sender, EventArgs e)
{
    Exception exception = Server.GetLastError();
    Elmah.ErrorSignal.FromCurrentContext().Raise(exception);
}

Didn't make any difference at all.

How can I handle errors happening before the controllers are called?

Brandon Linton · Accepted Answer · 2013-07-26 14:41:45Z

1

I wonder if this exception is just being added to the content of the HttpResponseMessage but is not actually being thrown as an exception. When implementing a dependency resolver class for use during constructor instantiation, it usually makes sense to attempt resolution, catch exceptions and return null.

For example, in non-API MVC controllers I've often used something like this:

public class UnityDependencyResolver : IDependencyResolver
{
    public readonly IUnityContainer Container;

    public UnityDependencyResolver(IUnityContainer container)
    {
        Container = container;
    }

    #region IDependencyResolver Members

    public object GetService(Type serviceType)
    {
        try
        {
            return Container.Resolve(serviceType);
        }
        catch (Exception ex)
        {
            if (ex.InnerException is TypeInitializationException)
                throw ex.InnerException;

            return null;
        }
    }
    ...

answered Jul 26, 2013 at 14:41

Brandon Linton

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1 Comment

Carl R Over a year ago

It makes sense if it does. I'll have to read up on the mvc source soon.

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