WebApi OData v3 OperationDescriptor 根据格式返回不同的 Title/Target URI（atom vs json）

Question

考虑以下使用 OData v3.

的简单 ASP.NET Web Api

MyEntity.cs

public class MyEntity
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

MyEntitiesController.cs

public class MyEntitiesController : ODataController
{
    public IEnumerable<MyEntity> Get()
    {
        return new MyEntity[] { new MyEntity() { Id = Guid.NewGuid(), Name = "Name" } };
    }

    [HttpPost]
    public string MyAction()
    {
        return "Hello World!";
    }
}

WebApiConfig.cs

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        var modelBuilder = new ODataConventionModelBuilder();
        modelBuilder.Namespace = "MyNamespace";
        modelBuilder.ContainerName = "MyContainer";
        modelBuilder.EntitySet<MyEntity>("MyEntities");

        var action = modelBuilder.Entity<MyEntity>().Action("MyAction");
        action.Returns<string>();

        foreach (var structuralType in modelBuilder.StructuralTypes)
        {
            // Resets the namespace so that the service contains only 1 namespace.
            structuralType.GetType().GetProperty("Namespace").SetValue(structuralType, "MyNamespace");
        }

        var model = modelBuilder.GetEdmModel();
        config.Routes.MapODataServiceRoute("OData", "odata", model);
    }
}

在客户端，我添加了一个简单的服务参考。

Program.cs

class Program
{
    static void Main(string[] args)
    {
        var contextAtom = new MyContainer(new Uri("http://localhost:63939/odata/"));
        contextAtom.Format.UseAtom();
        var myEntityAtom = contextAtom.MyEntities.First();

        // Outputs: http://localhost:63939/odata/MyEntities(guid'2c2431cd-4afa-422b-805b-8398b9a29fec')/MyAction
        var uriAtom = contextAtom.GetEntityDescriptor(myEntityAtom).OperationDescriptors.First().Target;
        Console.WriteLine(uriAtom);

        // Works fine using ATOM format!
        var responseAtom = contextAtom.Execute<string>(uriAtom, "POST", true);

        var contextJson = new MyContainer(new Uri("http://localhost:63939/odata/"));
        contextJson.Format.UseJson();
        var myEntityJson = contextJson.MyEntities.First();

        // Outputs: http://localhost:63939/odata/MyEntities(guid'f31a8332-025b-4dc9-9bd1-27437ae7966a')/MyContainer.MyAction
        var uriJson = contextJson.GetEntityDescriptor(myEntityJson).OperationDescriptors.First().Target;
        Console.WriteLine(uriJson);

        // Throws an exception using the JSON uri in JSON format!
        var responseJson = contextJson.Execute<string>(uriJson, "POST", true);

        // Works fine using ATOM uri in JSON format!
        var responseJson2 = contextJson.Execute<string>(uriAtom, "POST", true);
    }
}

我的问题是，根据用于查询实体的格式，操作描述符目标 URI 是不同的。来自 ATOM 的目标 URI 工作正常，但来自 JSON 的目标 URI 总是抛出异常。

有没有办法让操作描述符在使用两种格式（ATOM 和 JSON）时工作，而不是手动连接 URI？

请注意，我在使用 OData v4 时遇到了同样的问题，但将 MyNamespace.MyAction 作为标题和目标 URI 而不是 MyContainer.MyAction。

Answer 1

我能够重现这个问题，这是客户端的一个错误。我发现的唯一解决方法是扩展 MyContainer class 以提供调用操作的强类型方法：

namespace <NAMESPACE_OF_MYCONTAINER_CLASS>
{
    public partial class MyContainer
    {
        public double MyAction(Guid id)
        {
            Uri actionUri = new Uri(this.BaseUri,
                String.Format("MyEntities(guid'{0}')/MyAction", id)
                );

            return this.Execute<string>(actionUri, 
                "POST", true).First();
        }
    }
}

如所述here. I have tracked this problem and seems old, I found this post，其中一个人 (Uffe Lauesen) 在他第二个 post 中解释了当他阅读 ActionDescriptor 的标题（而不是目标）属性时的一些奇怪行为 class 当使用 json 格式时。

你还在他们的 github page.

中用 odata.net 打开了一个问题

更新：

我跟踪了这个问题，Atom 格式使用 NoOpEntityMetadataBuilder，它 return 是非计算操作（使用 atom 格式它解析 xml 并从提要中获取操作）。

internal override IEnumerable<ODataAction> GetActions()
{
    DebugUtils.CheckNoExternalCallers();
    return this.entry.NonComputedActions;
}

而不是 Json 格式使用 ODataConventionalEntityMetadataBuilder，其中 returns 计算的动作与 non-computed 动作串联：

internal override IEnumerable<ODataAction> GetActions()
{
    DebugUtils.CheckNoExternalCallers();
    return ODataUtilsInternal.ConcatEnumerables(this.entryMetadataContext.Entry.NonComputedActions, this.MissingOperationGenerator.GetComputedActions());
}

对于计算操作，我们结束了在 EdmLibraryExtensions 中调用此扩展函数：

internal static string FullName(this IEdmEntityContainerElement containerElement)
{
    Debug.Assert(containerElement != null, "containerElement != null");

    return containerElement.Container.Name + "." + containerElement.Name;
}

所以我相信这里最好没有return container.Name，只有containerElement.Name。运行在 github 中解决问题并发布正式版本之前，具有此最小更改的 Microsoft OData 库的补丁版本可以避免该问题。

Answer 2

截止到今天，OData/odata.net github的问题已经分配给某人，但仍然没有消息。

我决定编写自定义 OData 路径处理程序来支持 JSON 操作名称。它与以下 OData 路径模板一起工作 "for me"：~/action、~/entityset/key/action 和 ~/entityset/action.

CustomODataPathHandler.cs

internal class CustomODataPathHandler : DefaultODataPathHandler
{
    #region Methods

    protected override ODataPathSegment ParseAtEntityCollection(IEdmModel model, ODataPathSegment previous, IEdmType previousEdmType, string segment)
    {
        ODataPathSegment customActionPathSegment;
        if (TryParseCustomAction(model, previousEdmType, segment, out customActionPathSegment))
        {
            return customActionPathSegment;
        }

        return base.ParseAtEntityCollection(model, previous, previousEdmType, segment);
    }

    protected override ODataPathSegment ParseAtEntity(IEdmModel model, ODataPathSegment previous, IEdmType previousEdmType, string segment)
    {
        ODataPathSegment customActionPathSegment;
        if (TryParseCustomAction(model, previousEdmType, segment, out customActionPathSegment))
        {
            return customActionPathSegment;
        }

        return base.ParseAtEntity(model, previous, previousEdmType, segment);
    }

    protected override ODataPathSegment ParseEntrySegment(IEdmModel model, string segment)
    {
        var container = model.EntityContainers().First();
        if (CouldBeCustomAction(container, segment))
        {
            ODataPathSegment customActionPathSegment;
            if (TryParseCustomAction(model, segment, out customActionPathSegment))
            {
                return customActionPathSegment;
            }
        }

        return base.ParseEntrySegment(model, segment);
    }

    private static bool TryParseCustomAction(IEdmModel model, IEdmType previousEdmType, string segment, out ODataPathSegment pathSegment)
    {
        var container = model.EntityContainers().First();
        if (CouldBeCustomAction(container, segment))
        {
            var actionName = segment.Split('.').Last();
            var action = (from f in container.FindFunctionImports(actionName)
                          let parameters = f.Parameters
                          where parameters.Count() >= 1 && parameters.First().Type.Definition.IsEquivalentTo(previousEdmType)
                          select f).FirstOrDefault();

            if (action != null)
            {
                pathSegment = new ActionPathSegment(action);
                return true;
            }
        }

        pathSegment = null;
        return false;
    }

    private static bool TryParseCustomAction(IEdmModel model, string segment, out ODataPathSegment pathSegment)
    {
        var container = model.EntityContainers().First();
        if (CouldBeCustomAction(container, segment))
        {
            var actionName = segment.Split('.').Last();
            var action = (from f in container.FindFunctionImports(actionName)
                          where f.EntitySet == null && !f.IsBindable
                          select f).FirstOrDefault();

            if (action != null)
            {
                pathSegment = new ActionPathSegment(action);
                return true;
            }
        }

        pathSegment = null;
        return false;
    }

    private static bool CouldBeCustomAction(IEdmEntityContainer container, string segment)
    {
        return segment.StartsWith(container.Name + ".", StringComparison.OrdinalIgnoreCase);
    }

    #endregion
}

请注意，由于 JSON 操作名称包含一个点“.”，我必须在 web.config 中添加一个处理程序（以避免与静态文件处理程序冲突）：

web.config

<system.webServer>
  <handlers>
    <add name="UrlRoutingHandler" path="odata/*" verb="*" type="System.Web.Routing.UrlRoutingHandler, System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
  </handlers>
</system.webServer>

此外，WebApiConfig 更改为使用自定义 OData 路径处理程序：

WebApiConfig.cs

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        var modelBuilder = new ODataConventionModelBuilder();
        modelBuilder.Namespace = "MyNamespace";
        modelBuilder.ContainerName = "MyContainer";
        modelBuilder.EntitySet<MyEntity>("MyEntities");

        var action = modelBuilder.Entity<MyEntity>().Action("MyAction");
        action.Returns<string>();

        modelBuilder.Action("Test");

        foreach (var structuralType in modelBuilder.StructuralTypes)
        {
            // Resets the namespace so that the service contains only 1 namespace.
            structuralType.GetType().GetProperty("Namespace").SetValue(structuralType, "MyNamespace");
        }

        var model = modelBuilder.GetEdmModel();
        config.Routes.MapODataServiceRoute("OData", "odata", model, new CustomODataPathHandler(), ODataRoutingConventions.CreateDefault());
    }
}

Answer 3

请查看您的服务web.config。请将以下行中的 path="*." 更新为 path="odata/*"。这是为了处理 url 路径中的点。

<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />

WebApi OData v3 OperationDescriptor 根据格式返回不同的 Title/Target URI（atom vs json）

WebApi OData v3 OperationDescriptor returning different Title/Target URI depending on the format (atom vs json)

c#

json

asp.net-web-api

odata

atom-feed