Why is the response from my Web API not formed properly?

Question

I have a very basic Web API example that I constructed using the example code from this tutorial:

Code

Relevant Web.config Section

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <handlers>
      <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
      <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
      <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
    </handlers>
  </system.webServer>

Route Configuration

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }
}

View Model

public class Survey
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
}

ApiController

public class SurveysController : ApiController
{
    public IEnumerable<Survey> All()
    {
        using (ITSurveyEntities model = new ITSurveyEntities())
        {
            return new List<Survey>(
                from s in model.Surveys
                select new Survey
                {
                    Id = s.Id,
                    Name = s.Name,
                    Description = s.Description,
                });
        }
    }
}

and it's leveraging ITSurveyEntities, which was a generated ADO.NET Entity Data Model from the database, which only contains a single table right now, Survey.

In short, I don't think I'm trying to do anything special here.

Current Result

When I try and navigate to the API using something like http://localhost:1681/api/surveys, I get a response, but the file is named surveys with no extension. Further, if I try and Save As and give it say a txt extension, the download just fails.

Expected Result

I would expect that the API would return a file names surveys.json, like the example project does with products, and the browser would ask me to open or save the file.

What I've Tried

Comparing Web.config Files

I have compared the Web.config files between my project and the example code from the tutorial that works.

Comparing Routing

I have compared the routing configuration between my project and the example code from the tutorial that works.

Excluding WebDav

I've tried to exclude WebDav because my searches have indicated that it might be the cause. I did that by modifying the Web.config in a manner that matches what's on this blog.

UPDATE 1

Okay, after the guidance by Joe Enos I found that the issue was that the view model was named Survey also and so it was throwing an error about ambiguity between the CLR type and the EDM type.

I resolved that by renaming the view model to SurveyViewModel, and the request to http://localhost:1681/api/surveys now returns a HTTP 200 and downloads the file as expected.

Answer 1

If you take a look at the raw request and response using Fiddler or your browser's dev tools, you should find some clues as to the problem.