将 JSONAPI.NET 升级到最新版本 (0.3.0-pre-1) 后无法查询单个资源答案

【问题标题】：Can not query a single resource after upgrading JSONAPI.NET to latest version (0.3.0-pre-1)将 JSONAPI.NET 升级到最新版本 (0.3.0-pre-1) 后无法查询单个资源
【发布时间】：2015-02-24 09:37:41
【问题描述】：

将 JSONAPI.NET 升级到最新版本 (0.3.0-pre-1) 后，我无法查询单个资源（即 /{controller}/{id}）。我可以查询所有多个资源端点（即 /{controller}）。

它可能与JSONAPI.EntityFramework.Http.ApiController 有关，因为我使用System.Web.Http.ApiController 创建了一个控制器并且它工作正常。我使用了相同的 DbContext。

我已经关注/尝试了来自JSONAPI.TodoMVC.API 的所有代码。

这是我得到的错误：

{
"errors": [
    {
        "id": "6b49c8a9-d7b4-473e-80cd-c771fe1e7d13",
        "status": "500",
        "title": "System.AggregateException",
        "detail": "One or more errors occurred.",
        "inner": {
            "id": null,
            "status": "500",
            "title": "System.ArgumentException",
            "detail": "The Type AssetClass was not found in the DbContext with Type ApiContext",
            "inner": {
                "id": null,
                "status": "500",
                "title": "System.ArgumentException",
                "detail": "The member with identity 'ConeTec.DataServices.Web.Areas.WebApi.Models.AssetClass' does not exist in the metadata collection.\r\nParameter name: identity",
                "inner": null,
                "stackTrace": "   at System.Data.Entity.Core.Metadata.Edm.ItemCollection.GetItem[T](String identity, Boolean ignoreCase)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetKeyNames(Type type)"
            },
            "stackTrace": "   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetKeyNames(Type type)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetKeyProperties(Type type)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetByIdAsync(Type type, Object[] idValues)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.<GetByIdAsync>d__0`1.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at JSONAPI.Http.ApiController`1.<Get>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Threading.Tasks.TaskHelpersExtensions.<CastToObject>d__3`1.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()"
        }
   }
]

}

知道为什么会出现此错误吗？

谢谢！

S'pht'Kr @S'pht'Kr

csantero @csantero

这是完整的错误跟踪：

{
"errors": [
    {
        "id": "57a5f40e-b170-407f-982a-c7cad64539e9",
        "status": "500",
        "title": "System.AggregateException",
        "detail": "One or more errors occurred.",
        "inner": {
            "id": null,
            "status": "500",
            "title": "System.ArgumentException",
            "detail": "The Type AssetClass was not found in the DbContext with Type ApiContext",
            "inner": {
                "id": null,
                "status": "500",
                "title": "System.ArgumentException",
                "detail": "The member with identity 'ConeTec.DataServices.Web.Areas.WebApi.Models.AssetClass' does not exist in the metadata collection.\r\nParameter name: identity",
                "inner": null,
                "stackTrace": "   at System.Data.Entity.Core.Metadata.Edm.ItemCollection.GetItem[T](String identity, Boolean ignoreCase)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetKeyNames(Type type)"
            },
            "stackTrace": "   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetKeyNames(Type type)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetKeyProperties(Type type)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.GetByIdAsync(Type type, Object[] idValues)\r\n   at JSONAPI.EntityFramework.EntityFrameworkMaterializer.<GetByIdAsync>d__0`1.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at JSONAPI.Http.ApiController`1.<Get>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Threading.Tasks.TaskHelpersExtensions.<CastToObject>d__3`1.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()"
        },
        "stackTrace": "   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)\r\n   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)\r\n   at System.Threading.Tasks.Task.Wait()\r\n   at ConeTec.DataServices.Web.Filters.ApiUserContextAttribute.ExecuteActionFilterAsync(HttpActionContext actionContext, CancellationToken cancellationToken, Func`1 continuation) in c:\\CDS\\ConeTecGeoDb\\ConeTec.DataServices.Web\\Filters\\UserContextAttribute.cs:line 160\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<ExecuteActionFilterAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<ExecuteActionFilterAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()"
    }
]

}

这是我AssetClassesController的一个例子：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using ConeTec.DataServices.Web.Areas.WebApi.Models;
using JSONAPI.EntityFramework.Http;

namespace ConeTec.DataServices.Web.Areas.WebApi.Controllers {
    public class AssetClassesController : ApiController<AssetClass, ApiContext> {

    }
}

【问题讨论】：

这当然很有趣。如果您尝试具体化不在 DbContext 中的模型类型，则应引发此错误。但是你是说能成功得到/assetclasses/却不能得到/assetclasses/42？ AssetClass 是您的 DbContext 中的实体之一吗？或者这是对其他实体的请求的结果，而 AssetClass 是从成员属性返回的非实体类型？
是的，没错。我可以访问/assetclasses/，但不能访问/assetclasses/42。是的，AssetClass 是在我的 DbContext 中定义的。所有实体都有同样的问题。我刚刚创建了一个新的（没有任何关系），我遇到了同样的问题。如果我的控制器继承自 System.Web.Http.ApiController，一切正常。
这很难。我将不得不仔细查看代码，看看我是否有任何想法。我唯一想到的另一件事是导致它无法加载实体元数据。您可以发布您的ApiController 课程，包括您的using 声明吗？
另一个问题...如果模型对象跨项目或程序集，似乎实体框架的潜在错误可能会发生...AssetClass 是否在与您的ApiController 不同的项目中定义？这可能是一个因素。无论是什么原因造成的，都有一种解决方法。创建EntityFrameworkMaterializer 的子类并覆盖GetById 方法。您可以在其中包含逻辑以通过 ID 获取任何模型。失败的是 EFM 试图弄清楚如何自动做到这一点。明天我会发布更详细的答案。
我按要求发布了我的AssetClassesController。 Models/Controllers/ApiContext 都在同一个项目中。都在一个区域内。

标签： asp.net entity-framework json-api

【解决方案1】：

这个错误应该从https://github.com/SphtKr/JSONAPI.NET/pull/77 开始修复。

【讨论】：

【解决方案2】：

确保您在 ApiContext 类中将 AssetClass 定义为 DBSet<AssetClass> AssetClass

【讨论】：

【解决方案3】：

好的，我正在空中编码……在我的 iPhone 上……但试试看。

创建自己的EntityFrameworkMaterializer 子类并覆盖GetKeyNames 方法，如下所示：

protected override IEnumerable<string> GetKeyNames(Type type)
{
    this.DbContext.MetadataWorkspace.LoadFromAssembly(this.DbContext.GetType().Assembly);
    return base.GetKeyNames(type);
}

然后在您的ApiController 覆盖...

protected override JSONAPI.Core.IMaterializer MaterializerFactory()
{
    return new MyMaterializer(new ApiContext());
}

这样做有一些效率低下，但如果这解决了你的问题，那么我可以弄清楚在图书馆里做什么。

作为备用计划，只需使用重写的 GetKeyNames 方法返回每个模型类型的正确键名列表。（提示：如果这在 0.2.0 中对您有用，那么每次都可以安全地简单地返回 new List<string> { "Id" }...因为我最近发现这就是旧的 GetKeyNames 方法所能做的全部。）;-)

【讨论】：

感谢 S'pht'Kr。按照您的建议从程序集中加载不起作用。我选择了您的另一个建议，即返回new List<string> { "Id" }，它现在正在工作。但是，这似乎不是最佳解决方案；）
不确定是否有帮助，但我的 Web API 位于 Area。
不确定它是否与这个问题有关，但我不能在与IncludeInPayload(true) 的表示中包含关系。你觉得有关系吗？没有返回错误，根本不包括在内。
很可能相关，但未知。我正在阅读领域......据我所知，编译器和运行时对它们一无所知，它们严格来说是 MVC 的东西......意思是，EF 甚至不应该知道它们的区别。但我会进一步研究。
我已经覆盖了EntityFrameworkMaterializer.GetKeyNames 以查看System.Data.Entity.Core.Metadata.Edm.DataSpace.OSpace 而不是System.Data.Entity.Core.Metadata.Edm.DataSpace.CSpace，我现在可以获得单个资源。