Efcore: [Question] Where do column names get generated?

Created on 2 May 2019 · 24Comments · Source: dotnet/efcore

Describe what is not working as expected.

I am losing many hours and sleep debugging a showstopping issue for me. I have tried creating a repro test case, but the test case consistently passes. I'm looking for guidance on how I can find what line of code assigns column names to entities in the change tracking engine. Ideally I'd like to add a Breakpoint there, and instead of loading the EFCore nuget package, load the GItHub source locally and figure out how this is happening. - Either My stack trace is happening too late for me to see that there is a model mapping error somewhere, or EFCore has multiple places where it can generate a column name, and those places are not consistent.

If you are seeing an exception, include the full exceptions details (message and stack trace).

Error Message:
Microsoft.EntityFrameworkCore.DbUpdateException : An error occurred while updating the entries. See the inner exception for details.
---- System.Data.SqlClient.SqlException : Invalid column name 'GoodChild_ChildId'.
   at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.Execute(IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute(DbContext _, ValueTuple`2 parameters)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute(IEnumerable`1 commandBatches, IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(IReadOnlyList`1 entriesToSave)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(Boolean acceptAllChangesOnSuccess)
   at Microsoft.EntityFrameworkCore.DbContext.SaveChanges(Boolean acceptAllChangesOnSuccess)
   at JohnZabroski.Data.Context.DbContextBase.SaveChanges(Boolean acceptAllChangesOnSuccess)
   at JohnZabroski.Data.Testing.Specifications.PersistenceSpecification`1.Verify(VerifyParameters parameters, TEntity entity)
   at JohnZabroski.Data.Testing.Configurations.EntityConfigurationTestBase`1.TestConfiguration()
----- Inner Stack Trace -----
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlDataReader.TryConsumeMetaData()
   at System.Data.SqlClient.SqlDataReader.get_MetaData()
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)
   at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior)
   at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.Execute(IRelationalConnection connection, DbCommandMethod executeMethod, IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.ExecuteReader(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.Execute(IRelationalConnection connection)

Steps to reproduce

I can't yet reproduce the issue. Creating a smaller issue, the problem does not show up. I suspect it has something to do with proxies, since the failure happens in my test suite with AutoFixture.

Further technical details

EF Core version: 2.2.4
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Windows 10 Pro
IDE: Visual Studio 2017 15.9.11

closed-question customer-reported

Source

jzabroski

All 24 comments

Hmm... I made some progress... immediately after filing this, I modified the my modelBuilder logic slightly and it worked - after 35 hours of debugging. Going to perform the Ostrich move now and stick my head in the sand.

The problem appears to be specific to having to, under certain conditions (that I cannot figure out), in a TPH you need to re-map the Id column for every child class and the parent base class.

Specifically, on the base class I do:

builder.HasKey(x => x.Id);
            builder.Property<long>(x => x.Id).HasColumnName("ChildId").UseSqlServerIdentityColumn<long>().ValueGeneratedOnAdd();

on the child classes, do:

builder.Property(x => x.Id).HasColumnName("ChildId"); // I'm not sure why doing this is necessary, and it seems to be required to do on all leaf entities

I have a hunch the primary reason I cannot reproduce this might have to do something with the fact that in the non-repro test case, I am generating the DB using EF, whereas in the repro (real world) code, I am using FluentMigrator. Specifically, when the column names are not picked by EF, and you are defining a foreign key relationship, you have to explicitly define the column names on every property on every entity participating in that key relationship (that is to say, both sides of the relationship). I'm not sure exactly why that would be the case, but the documentation on foreign key modeling says:

By convention, foreign key constraints are named FK_<dependent type name>_<principal type name>_<foreign key property name>. For composite foreign keys <foreign key property name> becomes an underscore separated list of foreign key property names.

It seems like somehow I am hitting this code path in the system, when I should not necessarily hit it. Perhaps Table-per-hierarchy is triggering this code path?

jzabroski on 2 May 2019

@jzabroski I am guessing that ChildId is defined on an abstract base class. Then you are hitting https://github.com/aspnet/EntityFrameworkCore/issues/14055. But in general we add the prefix if you have two properties with the same name defined on different types mapped to the same table. It's safer to assume they should be mapped to different columns.

FYI you can call modelBuilder.Model.ToDebugString(); at the end of OnModelCreating to print out the whole model in case this helps with debugging.