OData+EF on inherited back-navigations

[raffaeler]

This is the same issue reported here: https://entityframework.codeplex.com/workitem/2903

We have troubles using OData queries on a service based on EntityFramework.
The problem arises when we try to expand inherited back-navigation properties.
In attachment you can find a minimal example which reproduces the problem.

We have entities in the following hierarchy:
Base-->Derived-->DerivedDerived-->DerivedDerivedDerived
A back-navigation is declared on "Base" and queried on all four entity-types just to find that it only works on "Base" and "DerivedDerivedDerived" (i.e. only the least and most extended types).

The queries we tried are:
[...]/odata/Base?$expand=BackNav
[...]/odata/Derived?$expand=BackNav
[...]/odata/DerivedDerived?$expand=BackNav
[...]/odata/DerivedDerivedDerived?$expand=BackNav

Only cases 1 and 4 are working.

Cases 2 and 3 throw exception:
{ "error":{ "code":"","message":"An error has occurred.","innererror":{ "message":"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata.metadata=minimal'.","type":"System.InvalidOperationException","stacktrace":"","internalexception":{ "message":"An error occurred while preparing the command definition. See the inner exception for details.","type":"System.Data.Entity.Core.EntityCommandCompilationException","stacktrace":" at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition..ctor(DbProviderFactory storeProviderFactory, DbCommandTree commandTree, DbInterceptionContext interceptionContext, IDbDependencyResolver resolver, BridgeDataReaderFactory bridgeDataReaderFactory, ColumnMapFactory columnMapFactory)\r\n at ...

OdataTest.zip

[Lingxi-Li]

I noticed the use of the System.Web.OData namespace. Should investigate from the WebApi.OData level. Forwarded to OData/WebApi#792.