5.1.1: ProjectTo, Explicit Expansion creaing problems.

[Thomas Tomiczek]

I am working on mapping OData QueryOptions to Automapper and then Entity Framework.

I am stuck with explicit expansion.

* If I do not define it, obviously all navigation properties do get epxanded. That DOES work.

* If I add explicit expansion like this:

.ForMember(d => d.Portfolio, o => { o.MapFrom(s => s.CustomerPortfolio); o.ExplicitExpansion(); })

 

  then this does work - the navigation does not show up. This does work.

* If I add then property back then explicitly using ProjectTo<T>(expand); with expand being a string array [1] with [1] = "CustomerPortfolio", then I get an EF error:

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":"The specified type member 'Portfolio' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.","type":"System.NotSupportedException","stacktrace":"   at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MemberAccessTranslator.TypedTranslate(ExpressionConverter parent, MemberExpression linq)\r\n   at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)\r\n   at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)\r\n   at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MemberInitTranslator.TypedTranslate(ExpressionConverter 

(that is from OData, but as the stack trace shows this is EF internal).

* If I add the property back via the projected target name ("Portfolio") then I get the following error:

Object reference not set to an instance of an object.

   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)
   at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()
   at System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext()
   at System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider()
   at AutoMapper.QueryableExtensions.ProjectionExpression.To[TResult](IDictionary`2 parameters, IEnumerable`1 memberPathsToExpand)
   at AutoMapper.QueryableExtensions.ProjectionExpression.To[TResult](Object parameters, Expression`1[] membersToExpand)
   at AutoMapper.QueryableExtensions.Extensions.ProjectTo[TDestination](IQueryable source, IConfigurationProvider configuration, Object parameters, Expression`1[] membersToExpand)
   at AutoMapper.QueryableExtensions.Extensions.ProjectTo[TDestination](IQueryable source, Object parameters, Expression`1[] membersToExpand)
   at Red.Web.Api.Code.ODataExtensions.ProjectTo[S,T](IQueryable`1 query, ODataQueryOptions`1 options) in C:\Work\ObjectBrief\Red.Web.Api\Code\ODataExtensions.cs:line 31
   at Red.Web.Api.Controllers.CodPropertyController.Get(ODataQueryOptions`1 options) in C:\Work\ObjectBrief\Red.Web.Api\Controllers\CodPropertyController.cs:line 29
   at lambda_method(Closure , Object , Object[] )
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)

Which is not really helpfull either. It seems that both ways are not working.

Anyone an idea how to get this working? Is this a known/documented bug?

The documentation at https://github.com/AutoMapper/AutoMapper/wiki/Queryable-Extensions

says:

To control which members are expanded during projection, set ExplicitExpansion in the configuration and then pass in the members you want to explicitly expand:

Which would indicate that the second version is correct - but that also generates a not too nice error.