Effort throws InvalidOperationException: Sequence contains more than one matching element

c# effort entity-framework

Question

I'm using Effort in a regular way by creating a connection and passing it to DB Context:

public class InMemoryContextInitializer
{
    public void BeforeAllTests()
    {
        Effort.Provider.EffortProviderConfiguration.RegisterProvider();
    }

    public DbConnection BeforeEachTest()
    {
        return Effort.DbConnectionFactory.CreateTransient();
    }

    public void AfterEachTest(DbConnection prevUsedConnection)
    {
        prevUsedConnection.Dispose();
    }
}

and something like this:

    private static InMemoryContextInitializer _testHarness;
    private DbConnection _conn;
    private MyDbContext _myContext;

    [ClassInitialize]
    public static void BeforeAllTests(TestContext testCtx)
    {
        _testHarness = new InMemoryContextInitializer();
        _testHarness.BeforeAllTests(); // registers provider
    }

    [TestInitialize]
    public void BeforeTest()
    {
        _conn = _testHarness.BeforeEachTest();
        _myContext = new MyDbContext(_conn);
    }

    [TestCleanup]
    public void AfterTest()
    {
        _testHarness.AfterEachTest(_conn);
    }

All my Effort tests pass just fine except one which throws this:

System.Data.DataException: An exception occurred while initializing the database. See the InnerException for details. ---> 
System.Data.Entity.Infrastructure.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---> 
System.Data.Entity.Core.UpdateException: An error occurred while updating the entries. See the inner exception for details. ---> 
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> 
NMemory.Exceptions.NMemoryException: Error code: GenericError ---> 
System.InvalidOperationException: Sequence contains more than one matching element

    at System.Linq.Enumerable.SingleOrDefault(IEnumerable`1 source, Func`2 predicate)
   at NMemory.Tables.TableCollection.FindTable(Type entityType)
   at NMemory.Utilities.TableCollectionExtensions.FindTable(TableCollection tableCollection)
   at NMemory.Execution.CommandExecutor.ExecuteInsert(T entity, IExecutionContext context)
   at NMemory.Tables.DefaultTable`2.InsertCore(TEntity entity, Transaction transaction)
   at Effort.Internal.DbManagement.Engine.ExtendedTable`2.InsertCore(TEntity entity, Transaction transaction)
   at NMemory.Tables.Table`2.Insert(TEntity entity, Transaction transaction)
 --- End of inner exception stack trace ---
    at NMemory.Tables.Table`2.Insert(TEntity entity, Transaction transaction)
   at Effort.Internal.Common.DatabaseReflectionHelper.WrapperMethods.InsertEntity(ITable`1 table, TEntity entity, Transaction transaction)
 --- End of inner exception stack trace ---
    at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Effort.Internal.Common.DatabaseReflectionHelper.InsertEntity(ITable table, Object entity, Transaction transaction)
   at Effort.Internal.CommandActions.InsertCommandAction.CreateAndInsertEntity(ITable table, IList`1 memberBindings, Transaction transaction)
   at Effort.Internal.CommandActions.InsertCommandAction.ExecuteNonQuery(ActionContext context)
   at Effort.Provider.EffortEntityCommand.ExecuteNonQuery()
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<NonQuery>b__0(DbCommand t, DbCommandInterceptionContext`1 c)
   at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch(TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
   at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteNonQuery()
   at System.Data.Entity.Core.Mapping.Update.Internal.DynamicUpdateCommand.Execute(Dictionary`2 identifierValues, List`1 generatedValues)
   at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
 --- End of inner exception stack trace ---
    at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.<Update>b__2(UpdateTranslator ut)
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update(T noChangesResult, Func`2 updateFunction)
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update()
   at System.Data.Entity.Core.Objects.ObjectContext.<SaveChangesToStore>b__35()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction(Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesToStore(SaveOptions options, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction)
   at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClass2a.<SaveChangesInternal>b__27()
   at System.Data.Entity.Infrastructure.DefaultExecutionStrategy.Execute(Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesInternal(SaveOptions options, Boolean executeInExistingTransaction)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChanges(SaveOptions options)
   at System.Data.Entity.Internal.InternalContext.SaveChanges()
 --- End of inner exception stack trace ---
    at System.Data.Entity.Internal.InternalContext.SaveChanges()
   at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
   at System.Data.Entity.DbContext.SaveChanges()
   at System.Data.Entity.Migrations.History.HistoryRepository.BootstrapUsingEFProviderDdl(VersionedModel versionedModel)
   at System.Data.Entity.Internal.InternalContext.<SaveMetadataToDatabase>b__7()
   at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
   at System.Data.Entity.Internal.InternalContext.SaveMetadataToDatabase()
   at System.Data.Entity.Internal.DatabaseCreator.CreateDatabase(InternalContext internalContext, Func`3 createMigrator, ObjectContext objectContext)
   at System.Data.Entity.Internal.InternalContext.CreateDatabase(ObjectContext objectContext, DatabaseExistenceState existenceState)
   at System.Data.Entity.Database.Create(DatabaseExistenceState existenceState)
   at System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context)
   at System.Data.Entity.Internal.InternalContext.<>c__DisplayClassf`1.<CreateInitializationAction>b__e()
   at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
 --- End of inner exception stack trace ---
    at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
   at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization()
   at System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c)
   at System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase()
   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 System.Linq.Queryable.Count(IQueryable`1 source)

   at Model.MyProj... my test method call stack here

I use multiple DB contexts in these tests and it all works except for this case:

var query = db.MyEntities.Count(); // will throw the exception above ONLY FOR SOME DB CONTEXTS

In fact any operation on this context like Add will throw.

I could not find anyone having the same problem on Effort website or by googling. Maybe it's a bug? I'm using the latest version of Effort - 1.1.4 and Entity Framework - 6.1.3.

I checked for any special thing about DbContext or the entity class and didn't find anything.

Popular Answer

I had this issue and found that using a separate connection (Effort.DbConnectionFactory.CreatePersistent) for each context solved the issue.

In my case, each context operates over entirely different tables, so there shouldn't have been a conflict in Effort / NMemory - so I think the bug report is sound - but this information may unblock people in the meantime.

The trade off is that this could be warning you that you actually do have two contexts operating on the same table, which would be bad - so you'll have to watch out for this too.




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