.Net WebApi OData返回Queryable的操作

Question

我希望实现接近RateProduct操作的内容:http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/odata-actions

在该教程中,它被定义为:

[HttpPost]
public int RateProduct([FromODataUri] int key, ODataActionParameters parameters) 
{ 
    // ...
}

ODataModelBuilder modelBuilder = new ODataConventionModelBuilder();
modelBuilder.EntitySet<Product>("Products");

// New Code
ActionConfiguration rateProduct = modelBuilder.Entity<Product>().Action("RateProduct");
rateProduct.Parameter<int>("Rating");
rateProduct.Returns<int>();

但是,我有一个Location实体的用例,它足够聪明,可以返回其周围某个半径范围内的其他位置.它大致应该是这样的:

[HttpPost]
public IQueryable<Location> GetLocationsWithinRadius([FromODataUri] int key, ODataActionParameters parameters) 
{ 
    // Get the Location instance intended to be the center of the radius by using the key
    // Do a radius search around it using (int)parameters["radius"] as the radius
    // return the IQueryable<Location> of all location found within that radius
}

ODataModelBuilder modelBuilder = new ODataConventionModelBuilder();
modelBuilder.EntitySet<Location>("Locations");

// New Code
ActionConfiguration getLocations = modelBuilder.Entity<Location>().Action("GetLocationsWithinRadius");
getLocations.Parameter<int>("radius");
getLocations.Returns<IQueryable<Location>>();

我很乐意让它工作,目前它在返回类型是一个时不起作用IQueryable<Location>.如果返回类型是一个类似int的原语,那么它可以正常工作,否则当我在fiddler中创建一个帖子时会出现以下错误(帖子类似于http://localhost:2663/odata/Locations(2112)/GetLocationsWithinRadiusRequest主体{radius: 50}):

{
  "odata.error":{
    "code":"","message":{
      "lang":"en-US","value":"An error has occurred."
    },"innererror":{
      "message":"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata=minimalmetadata; streaming=true; charset=utf-8'.","type":"System.InvalidOperationException","stacktrace":"","internalexception":{
        "message":"The related entity set could not be found from the OData path. The related entity set is required to serialize the payload.","type":"System.Runtime.Serialization.SerializationException","stacktrace":"   at System.Web.Http.OData.Formatter.Serialization.ODataFeedSerializer.WriteObject(Object graph, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)\r\n   at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.<>c__DisplayClassa.<WriteToStreamAsync>b__9()\r\n   at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)"
      }
    }
  }
}

是否有可能做我想要完成的事情？如果是的话,我敢问,返回后IQueryable<Location>是否可以与odata paramaters组合......(那会很好)？

谢谢

Answer 1

看起来您的操作配置不正确.尝试以下操作,看看它是否有效:

//getLocations.Returns<IQueryable<Location>>();
getLocations.ReturnsCollectionFromEntitySet<Location>("Locations");