Trouble enabling OData v4.0 routing in ASP.NET Web API 2.2

Question

I am trying to implement OData routing in my ASP.NET web api. For guidance, I looked at this tutorial: http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/odata-v4/create-an-odata-v4-endpoint.

However, I keep on getting an error message in the MapODataServiceRoute() function. Apparently, the function is expecting a Microsoft.OData.Edm.IEdmModel, and my builder's GetEdmModel() function only returns Microsoft.Data.Edm.IEdmModel.

I did some research online. Microsoft.Data.Edm is a library for the older version of OData. Microsoft.OData.Edm is for OData v4.0, which is why I commented out Microsoft.Data.Edm in WebApiConfig.cs file. Here is my code.

using MyApp.Models;
// using Microsoft.Data.Edm;
using Microsoft.OData.Edm;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Headers;
using System.Web.Http;
using System.Web.Http.OData.Builder;
using System.Web.OData.Extensions;
using System.Web.OData.Routing;

namespace MyAppAPI
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Enable attribute routing
            config.MapHttpAttributeRoutes();

            // Enable OData routing
            config.MapODataServiceRoute(
                routeName: "MyApp",
                routePrefix: "odata",
                model: GetEdmModel());

            // Conventional routing
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            // Uncomment the following line of code to enable query support for actions with an IQueryable or IQueryable<T> return type.
            // To avoid processing unexpected or malicious queries, use the validation settings on QueryableAttribute to validate incoming queries.
            // For more information, visit http://go.microsoft.com/fwlink/?LinkId=279712.
            config.EnableQuerySupport();

            // To disable tracing in your application, please comment out or remove the following line of code
            // For more information, refer to: http://www.asp.net/web-api
            config.EnableSystemDiagnosticsTracing();

            // Trying to get most browsers (i.e. Google Chrome) to return JSON
            config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
        }

        // Configure modesl to use Odata
        public static IEdmModel GetEdmModel()
        {
            ODataConventionModelBuilder builder = new ODataConventionModelBuilder();
            builder.EntitySet<ModelA>("ModelA");
            builder.EntitySet<ModelB>("ModelB");
            return builder.GetEdmModel();
        }

    }
}

However, I am still getting an error message:

Error   1   Cannot implicitly convert type 'Microsoft.Data.Edm.IEdmModel' to 'Microsoft.OData.Edm.IEdmModel'. An explicit conversion exists (are you missing a cast?)

Is there a clean way to get a Microsoft.OData.Edm.IEdmModel? Or am I going to have to just do a cast?

Christopher Spears Christopher Spears · Accepted Answer · 2015-03-25T19:50:11

Replacing System.Web.Http.OData.Builder with System.Web.OData.Builder seems to work.

Here is the link with the explanation: https://devblogs.microsoft.com/aspnet/getting-started-with-asp-net-web-api-2-2-for-odata-v4-0/

I think this line pretty much sums it up though:

The assembly name and the root namespace are now System.Web.OData instead of System.Web.Http.OData.

The headers I am using are now:

using MyApp.Models;
// using Microsoft.Data.Edm;
using Microsoft.OData.Edm;
using System.Net.Http.Headers;
using System.Web.Http;
// using System.Web.Http.OData.Builder;
using System.Web.OData.Builder;
using System.Web.OData.Extensions;

Trouble enabling OData v4.0 routing in ASP.NET Web API 2.2

3 Answers