努力拋出 InvalidOperationException：序列包含多個匹配元素

Question

我通過創建連接並將其傳遞給 DB Context 以常規方式使用 Effort：

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

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

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

和這樣的事情：

    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);
    }

我所有的 Effort 測試都通過了，除了一個拋出這個：

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

我在這些測試中使用了多個數據庫上下文，除了這種情況外，其他一切都有效：

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

事實上，在這個上下文上的任何操作，比如Add都會拋出。

我無法在 Effort 網站上或通過谷歌搜索找到任何有同樣問題的人。 也許這是一個錯誤？ 我使用的是最新版本的 Effort - 1.1.4 和 Entity Framework - 6.1.3。

我檢查了有關 DbContext 或實體類的任何特殊內容，但沒有找到任何內容。

Answer 1

我遇到了這個問題，發現為每個上下文使用單獨的連接（ Effort.DbConnectionFactory.CreatePersistent ）解決了這個問題。

就我而言，每個上下文都在完全不同的表上運行，因此 Effort / NMemory 中不應該存在沖突 - 所以我認為錯誤報告是合理的 - 但同時這些信息可能會阻止人們。

權衡是，這可能會警告您，您實際上確實在同一個表上運行了兩個上下文，這很糟糕 - 因此您也必須注意這一點。