Sequence Contains more than one element.

Question

Hi guys I am using EF in my application. Initially the database wasn't created yet in the DB server instead my application will create it based on my model. So here's the problem when I run the program I'm encountering this error Count '_temp.Count' threw an exception of type 'System.InvalidOperationException' int {System.InvalidOperationException} Sequence Contains more than one element. I need your help guys. Thanks in advance.

Nattudurai Eswaramurthy · Answer

HI Single and SingleOrDefault are designed to throw if more that one match exists in the sequence. A consequence of this is that the entire sequence must be iterated prior to completion. It does not sound like this is what you want. Try FirstOrDefault instead: Feature f = o . Features . FirstOrDefault ( e => e . vcr_LinkName == PageLink && e . bit_Activate == true ); This will (generally) perform better because it completes as soon as a match is found. Please mark this answer as accepted answer if it resolves your problem.

boycoto · Answer

Hi Vulpes still remember my post on employee profile? I made some modification I added a repository on my project. public virtual TObject Create(TObject TObject) { var newEntry = DbSet.Add(TObject); return newEntry; } public virtual int Commit() { if (!shareContext) return _database.SaveChanges(); return 0; } To insert the record to the database from csv try { foreach(Employee ep in profile) { _employeeData.Create(ep); } _employeeData.Commit(); } catch(Exception ex) { System.Diagnostics.Debug.Write(ex.StackTrace); }

Vulpes · Answer

As Nattudurai said the Single() extension method requires there to be exactly one matching element. If there's more than one it throws an exception. So if you just want to get one element use First() instead.

boycoto · Answer

Here's the stack trace at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source) at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.GetQualifiedTableName(XDocument model String entitySetName) at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer. b__6d( f__AnonymousType2c`2 h__TransparentIdentifier62) at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext() at System.Linq.Enumerable. d__31`3.MoveNext() at System.Linq.Enumerable. d__71`1.MoveNext() at System.Linq.Enumerable. d__71`1.MoveNext() at System.Linq.Enumerable. d__81`1.MoveNext() at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff(XDocument sourceModel XDocument targetModel String connectionString) at System.Data.Entity.Internal.InternalContext.ModelMatches(XDocument model) at System.Data.Entity.Internal.ModelCompatibilityChecker.CompatibleWithModel(InternalContext internalContext ModelHashCalculator modelHashCalculator Boolean throwIfNoMetadata) at System.Data.Entity.Internal.InternalContext.CompatibleWithModel(Boolean throwIfNoMetadata) at System.Data.Entity.Database.CompatibleWithModel(Boolean throwIfNoMetadata) at System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context) at System.Data.Entity.Internal.InternalContext. c__DisplayClass8. b__6() at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() at System.Data.Entity.Internal.LazyInternalContext. 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.Initialize() 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.Internal.Linq.InternalSet`1.ActOnSet(Action action EntityState newState Object entity String methodName) at System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity) at System.Data.Entity.DbSet`1.Add(TEntity entity) at UpdateRepository`1.Create(TObject TObject) in

boycoto · Answer

I'm loading a bulk of data into an entity and uses foreach loop to store each record to the database.