ODataController 返回 HTTP 406 不可接受

Question

我正在 Web API 2.2 上构建 OData 3 服务。

该服务正在正确返回我的实体的元数据，但在我查询其中一个实际实体时返回 406 Not Available。我已经做了很多研究（我目前正在学习几个教程），但我还没有找到任何真正有效的东西。

这是我的 WebApiConfig：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using System.Web.OData.Builder;
using System.Web.OData.Extensions;

namespace MyProject
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            ODataModelBuilder builder = new ODataConventionModelBuilder();

            builder.EntitySet<MarvelCharacter>("MarvelCharacters");
            config.MapODataServiceRoute(
                routeName: "Marvel",
                routePrefix: "dude",
                model: builder.GetEdmModel());
        }
    }
}

还有我的控制器（不完整，但你明白了）：

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.OData;
using System.Web.Http.OData.Query;
using Microsoft.Data.OData;
using MyProject;

namespace MyProject.Controllers
{
    public class MarvelCharactersController : ODataController
    {
        private static ODataValidationSettings _validationSettings = new ODataValidationSettings();

        // GET: odata/MarvelCharacters
        public IHttpActionResult GetMarvelCharacters(ODataQueryOptions<MarvelCharacter> queryOptions)
        {
            // validate the query.
            try
            {
                queryOptions.Validate(_validationSettings);
            }
            catch (ODataException ex)
            {
                return BadRequest(ex.Message);
            }

            var entities = new myEntities();
            var marvelCharacters = (from c in entities.MarvelCharacters select c).ToList();

            return Ok<IEnumerable<MarvelCharacter>>(marvelCharacters);
        }
    }
}

Answer 1

事实证明，这个问题的答案非常简单，但我能找到的任何文档都没有很好地涵盖。

我试图在 WebAPI 2.2 上实现 OData 3 端点。我正在学习几个不同的教程，一些针对 OData 3，一些针对 OData 4。

我在 WebApiConfig 中使用 OData 4 (System.Web.OData)，在控制器中使用 OData 3 (System.Web.Http.OData)。事实证明，他们在一起玩得不好。

我决定在这里发布答案，以防其他人有类似的问题。

为了增加一点价值，因为无论如何我都混合使用了，所以我决定继续设置对版本 3 和 4 的支持，方法是在我的 WebApiConfig 中为命名空间设置别名，然后创建版本化控制器。

WebApiConfig：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using ODataV3 = System.Web.Http.OData;
using ODataV4 = System.Web.OData;

namespace MyProject
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // OData V3 Route

            ODataV3.Builder.ODataModelBuilder builder3 = new ODataV3.Builder.ODataConventionModelBuilder();

            builder3.EntitySet<MarvelCharacter>("MarvelCharactersV3");
            // The MapODataRoute function is deprecated in WebAPI 2.2,
            // but I haven't found an alternative for supporting OData 3.
            config.Routes.MapODataRoute(
                routeName: "Marvel3",
                routePrefix: "dude3",
                model: builder3.GetEdmModel());

            // ODate V4 Route

            ODataV4.Builder.ODataModelBuilder builder4 = new ODataV4.Builder.ODataConventionModelBuilder();

            builder4.EntitySet<MarvelCharacter>("MarvelCharactersV4");
            ODataV4.Extensions.HttpConfigurationExtensions.MapODataServiceRoute(
                configuration: config,
                routeName: "Marvel4",
                routePrefix: "dude4",
                model: builder4.GetEdmModel());
        }
    }
}

MarvelCharactersV3 (OData 3)：

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.OData; // OData V3
using System.Web.Http.OData.Query;
using Microsoft.Data.OData;
using MyProject;

namespace MyProject.Controllers
{
    public class MarvelCharactersV3Controller : ODataController
    {
        private static ODataValidationSettings _validationSettings = new ODataValidationSettings();

        // GET: odata/MarvelCharacters
        public IHttpActionResult GetMarvelCharactersV3(ODataQueryOptions<MarvelCharacter> queryOptions)
        {
            // validate the query.
            try
            {
                queryOptions.Validate(_validationSettings);
            }
            catch (ODataException ex)
            {
                return BadRequest(ex.Message);
            }

            var entities = new myEntities();
            var marvelCharacters = (from c in entities.MarvelCharacters select c).ToList();

            return Ok<IEnumerable<MarvelCharacter>>(marvelCharacters);
        }
    }
}

MarvelCharactersV4 (OData 4)：

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web.OData; // OData 4
using System.Web.OData.Query;
using Microsoft.Data.OData;
using MyProject;

namespace MyProject.Controllers
{
    public class MarvelCharactersV4Controller : ODataController
    {
        private static ODataValidationSettings _validationSettings = new ODataValidationSettings();

        // GET: odata/MarvelCharacters
        public IHttpActionResult GetMarvelCharactersV4(ODataQueryOptions<MarvelCharacter> queryOptions)
        {
            // validate the query.
            try
            {
                queryOptions.Validate(_validationSettings);
            }
            catch (ODataException ex)
            {
                return BadRequest(ex.Message);
            }

            var entities = new myEntities();
            var marvelCharacters = (from c in entities.MarvelCharacters select c).ToList();

            return Ok<IEnumerable<MarvelCharacter>>(marvelCharacters);
        }
    }
}

它可能不是最好的架构（我可能会创建一个库来整合控制器之间的类似代码），但我已经测试过，我可以通过 OData 3 和 OData 4 成功查询，所以我很满意它暂时。