Question

尝试将Microsoft OData v4堆栈与Mongo C＃驱动程序集成。我想公开一个Mongo集合并针对ExtraElements词典中包含的字段启用OData $ filter操作。

我创建了一个最小的问题示例。从Visual Studio 2015中的空WebAPI项目开始，我创建了以下模型：

  public class TestEntity
  {
    [BsonId, BsonRepresentation(BsonType.ObjectId)]
    public string _id { get; set; }

    public string Id { get; set; }

    [BsonExtraElements]
    public Dictionary<string, object> ExtraElements { get; set; }
  }

我通过在WebApiConfig.Register()方法末尾添加以下内容，通过OData公开了EDM EntitySet：

  // OData
  var edmBuilder = new ODataConventionModelBuilder();
  edmBuilder.EntitySet<TestEntity>("test");

  config.MapODataServiceRoute("odata", "odata", edmBuilder.GetEdmModel());

最后，我创建了一个简单的TestController：

  public class TestController : ODataController
  {
    [EnableQuery(AllowedFunctions = Microsoft.AspNet.OData.Query.AllowedFunctions.All)]
    public IQueryable<TestEntity> Get()
    {
      var mongo = new MongoClient();
      var db = mongo.GetDatabase("test");
      var collection = db.GetCollection<TestEntity>("test");
      var result = collection.AsQueryable() as IQueryable<TestEntity>;
      return result;
    }
  }

我在Mongo集合中添加了一个实际对象：

> db.test.insert( {Id:'test', Name:'testName'})                                                   WriteResult({ "nInserted" : 1 })
> db.test.find()

{“ _id”：ObjectId（“ 5c266040fd7e5a3c63b33cd8”），“ Id”：“ test”，“ Name”：“ testName”}

现在，只要不尝试在ExtraElements上使用$ filter，我就可以查询find：

http://localhost:63927/odata/test

{"@odata.context":"http://localhost:63927/odata/$metadata#test","value":[{"Id":"test","Name":"testName","_id":"5c266040fd7e5a3c63b33cd8"}]}

但是，如果我尝试针对Name（其中一个ExtraElements）进行过滤，则会发生以下错误：

http://localhost:63927/odata/test？$ filter = Name％20eq％20％27testName％27

Message: Convert(IIF((({document}{ExtraElements} != null) AndAlso {document}{ExtraElements}.ContainsKey(\"Name\")), {document}{ExtraElements}.Item[\"Name\"], null)) is not supported.

Exception: System.InvalidOperationException

Stack Trace:
   at MongoDB.Driver.Linq.Translators.PredicateTranslator.GetFieldExpression(Expression expression)
   at MongoDB.Driver.Linq.Translators.PredicateTranslator.TranslateComparison(Expression variableExpression, ExpressionType operatorType, ConstantExpression constantExpression)
   at MongoDB.Driver.Linq.Translators.PredicateTranslator.Translate(Expression node)
   at MongoDB.Driver.Linq.Translators.PredicateTranslator.Translate(Expression node, IBsonSerializerRegistry serializerRegistry)
   at MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslateWhere(WhereExpression node)
   at MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslatePipeline(PipelineExpression node)
   at MongoDB.Driver.Linq.Translators.QueryableTranslator.Translate(Expression node, IBsonSerializerRegistry serializerRegistry, ExpressionTranslationOptions translationOptions)
   at MongoDB.Driver.Linq.MongoQueryProviderImpl`1.Execute(Expression expression)
   at MongoDB.Driver.Linq.MongoQueryableImpl`2.GetEnumerator()
   at Microsoft.AspNet.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteResourceSet(IEnumerable enumerable, IEdmTypeReference resourceSetType, ODataWriter writer, ODataSerializerContext writeContext)
   at Microsoft.AspNet.OData.Formatter.ODataOutputFormatterHelper.WriteToStream(Type type, Object value, IEdmModel model, ODataVersion version, Uri baseAddress, MediaTypeHeaderValue contentType, IWebApiUrlHelper internaUrlHelper, IWebApiRequestMessage internalRequest, IWebApiHeaders internalRequestHeaders, Func`2 getODataMessageWrapper, Func`2 getEdmTypeSerializer, Func`2 getODataPayloadSerializer, Func`1 getODataSerializerContext)
   at Microsoft.AspNet.OData.Formatter.ODataMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__1b.MoveNext()

如果我将public string Name { get; set; }之类的属性添加到TestEntity类中，则过滤将按预期进行，但是，我正在寻找一种允许对BsonExtraElements进行过滤的解决方案。

为什么通过OData对ExtraElements应用$ filter时，Mongo IQueryable为什么抛出InvalidOperationException？

0 个答案: