Entity Framework “The data reader is incompatible with the specified complex type.”

I recently had this problem with a site I’m working on. I’m using Entity framework to access a bunch of legacy stored procedures, originally in MySQL but ported over to MSSQL. Having added the sprocs to EF and let it auto-generate it’s magic, I was shocked to find one of my calls throwing the following exception;

System.Data.EntityCommandExecutionException: The data reader is incompatible with the specified 'ChinookModel.GetVehicleDescFromModelId_Result1'. A member of the type, 'ivaluationid1', does not have a corresponding column in the data reader with the same name.
   at System.Data.Query.InternalTrees.ColumnMapFactory.GetMemberOrdinalFromReader(DbDataReader storeDataReader, EdmMember member, EdmType currentType, Dictionary`2 renameList)
   at System.Data.Query.InternalTrees.ColumnMapFactory.GetColumnMapsForType(DbDataReader storeDataReader, EdmType edmType, Dictionary`2 renameList)
   at System.Data.Query.InternalTrees.ColumnMapFactory.CreateColumnMapFromReaderAndType(DbDataReader storeDataReader, EdmType edmType, EntitySet entitySet, Dictionary`2 renameList)
   at System.Data.Query.InternalTrees.ColumnMapFactory.CreateFunctionImportStructuralTypeColumnMap(DbDataReader storeDataReader, FunctionImportMapping mapping, EntitySet entitySet, StructuralType baseStructuralType)
   at System.Data.EntityClient.EntityCommandDefinition.FunctionColumnMapGenerator.System.Data.EntityClient.EntityCommandDefinition.IColumnMapGenerator.CreateColumnMap(DbDataReader reader)
   at System.Data.Objects.ObjectContext.CreateFunctionObjectResult[TElement](EntityCommand entityCommand, EntitySet entitySet, EdmType edmType, MergeOption mergeOption)
   at System.Data.Objects.ObjectContext.ExecuteFunction[TElement](String functionName, MergeOption mergeOption, ObjectParameter[] parameters)
   at System.Data.Objects.ObjectContext.ExecuteFunction[TElement](String functionName, ObjectParameter[] parameters)
   at Chinook.Model.ChinookEntities.GetVehicleDescFromModelId(Nullable`1 modelid) in C:\_Dev\Chinook\Source\Chinook.Model\Chinook.Designer.cs:line 160
   at Chinook.Model.GlassGuideDataProvider.GetVehicleFromModelId(Int32 ModelId) in C:\_Dev\Chinook\Source\Chinook.Model\GlassGuideDataProvider.cs:line 104
   at Chinook.Services.VehicleDataLookup.GetVehicleForRegistration(String reg) in C:\_Dev\Chinook\Source\Chinook\Services\VehicleDataLookup.asmx.cs:line 81

It seemed to be moaning that one of the columns in the complex type I set for it to use as the return type, doesn’t match to a column actually being returned, despite entity framework having auto generated that type itself! The cause was, as is generally the case, user error. Inspecting the sproc a bit closer I noticed one of the columns was being returned twice, using the same name. EF generated me a call with an iValuation and iValuation1 column, but failed to match iValuation1 because in reality both columns were simply called iValuation! So a simple, and kind of obvious fix, but worth noting to stop someone else loose a little more hair when they’re confonted with this error!

  1. #1 by Aaron on December 20, 2012 - 02:18

    Thanks for this. I DID check the stored proc several times, but overlooked a similar error. Reading this made me take a closer look.

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