EDM 模型根上的 ASP.NET Web API OData 操作

Question

我正在使用 OData 构建 Web API 服务，并希望将方法公开为服务中的操作，如下所示。

http://myServer/odata/myAction

我目前正在按如下方式映射 OData 路由：

Dim modelBuilder As ODataModelBuilder = New ODataConventionModelBuilder
modelBuilder.EntitySet(Of Product)("Products")

Dim myAction = modelBuilder.Action("myAction")
myAction.Parameter(Of String)("Parameter1")
myAction.Returns(Of Boolean)()

Dim model As IEdmModel = modelBuilder.GetEdmModel
config.Routes.MapODataRoute("ODataRoute", "odata", model)

This wonderful tutorial 展示了如何将动作与这样的实体相关联：

http://myServer/odata/Products(1)/myAction

按照教程，我可以在创建模型后在 ProductsController 类中编写操作的方法，使用以下代码行：

Dim myAction = modelBuilder.Entity(Of Product).Action("myAction")

但是，如果我不想将动作与实体相关联，我应该在哪里编写动作的方法？有没有我需要写的 DefaultController 类？

Answer 1

我们目前不提供开箱即用的支持，但您自己很容易做到这一点。下面的示例（这个不错的示例实际上来自尚未公开的 Mike Wasson :-)）

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// CreateMovie is a non-bindable action. 
// You invoke it from the service root: ~/odata/CreateMovie
ActionConfiguration createMovie = modelBuilder.Action("CreateMovie");
createMovie.Parameter<string>("Title");
createMovie.ReturnsFromEntitySet<Movie>("Movies");

// Add a custom route convention for non-bindable actions.
// (Web API does not have a built-in routing convention for non-bindable actions.)
IList<IODataRoutingConvention> conventions = ODataRoutingConventions.CreateDefault();
conventions.Insert(0, new NonBindableActionRoutingConvention("NonBindableActions"));

// Map the OData route.
Microsoft.Data.Edm.IEdmModel model = modelBuilder.GetEdmModel();
config.Routes.MapODataRoute("ODataRoute", "odata", model, new DefaultODataPathHandler(), conventions);

--------------------------------------------------------------

// Implements a routing convention for non-bindable actions.
// The convention maps "MyAction" to Controller:MyAction() method, where the name of the controller 
// is specified in the constructor.
public class NonBindableActionRoutingConvention : IODataRoutingConvention
{
    private string _controllerName;

    public NonBindableActionRoutingConvention(string controllerName)
    {
        _controllerName = controllerName;
    }

    // Route all non-bindable actions to a single controller.
    public string SelectController(ODataPath odataPath, System.Net.Http.HttpRequestMessage request)
    {
        if (odataPath.PathTemplate == "~/action")
        {
            return _controllerName;
        }
        return null;
    }

    // Route the action to a method with the same name as the action.
    public string SelectAction(ODataPath odataPath, System.Web.Http.Controllers.HttpControllerContext controllerContext, ILookup<string, System.Web.Http.Controllers.HttpActionDescriptor> actionMap)
    {
        if (controllerContext.Request.Method == HttpMethod.Post)
        {
            if (odataPath.PathTemplate == "~/action")
            {
                ActionPathSegment actionSegment = odataPath.Segments.First() as ActionPathSegment;
                IEdmFunctionImport action = actionSegment.Action;

                if (!action.IsBindable && actionMap.Contains(action.Name))
                {
                    return action.Name;
                }
            }
        }
        return null;
    }
}

--------------------------------------------------

// Controller for handling non-bindable actions.
[ODataFormatting]
[ApiExplorerSettings(IgnoreApi = true)]
public class NonBindableActionsController : ApiController
{
    MoviesContext db = new MoviesContext();

    [HttpPost]
    public Movie CreateMovie(ODataActionParameters parameters)
    {
        if (!ModelState.IsValid)
        {
            throw new HttpResponseException(HttpStatusCode.BadRequest);
        }

        string title = parameters["Title"] as string;

        Movie movie = new Movie()
        {
            Title = title
        };

        db.Movies.Add(movie);
        db.SaveChanges();
        return movie;
    }

    protected override void Dispose(bool disposing)
    {
        db.Dispose();
        base.Dispose(disposing);
    }
}