如何避免使用移动服务与 Azure 主数据库建立不必要的连接？

Question

以下代码：

    private void IsolateIssue()
    {
        using (var context = new SomeName.Models.MobileServiceContext())
        {
            System.Diagnostics.Debug.WriteLine(context.Database.Connection.ConnectionString);
            var numberOfItems = context.TodoItems.Count();
        }
    }

导致错误（调用 var numberOfItems 时）：

“System.Data.SqlClient.SqlException”类型的异常发生在 EntityFramework.dll 但未在用户代码中处理 附加 信息：无法打开登录请求的数据库“master”。这 登录失败。用户“SomeLoginName”登录失败。

这是我的连接字符串：

"数据源=ServerName.database.windows.net；初始 目录=SomeDataBaseName；用户 ID=SomeLoginName;Password=SomePassword};异步 处理=True;TrustServerCertificate=False;"

很明显是连接不上master数据库。给定用户名和密码，我也无法使用 LinqPad 连接到主数据库（当我尝试时，我得到了类似的错误）。但是，它根本不应该连接到主数据库。当我尝试使用 Linqpad 登录 SomeDataBaseName 时，我成功获得了 todoItems 的数量（17）。这证明根本不需要为了给定的目的访问主数据库。

首先，我必须确保我可以获取移动服务中的商品数量。我怎么做？初始 Catalog 显示它应该连接到 SomeDataBaseName 并且不需要连接到主数据库来获取项目数。我如何避免它试图这样做？

如果有帮助，这里是堆栈跟踪：

StackTrace " 在 System.Data.SqlClient.SqlInternalConnection.OnError（SqlException 异常，布尔 breakConnection，Action1 wrapCloseInAction)\r\n at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)\r\n at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)\r\n at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)\r\n at System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK)\r\n at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)\r\n at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)\r\n at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)\r\n at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData)\r\n at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)\r\n at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)\r\n at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)\r\n at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)\r\n at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)\r\n at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource1 重试，DbConnectionOptions userOptions，DbConnectionInternal& 连接）\r\n 在 System.Data.ProviderBase.DbConnectionFactory.TryGetConnection( DbConnection owningConnection, TaskCompletionSource1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)\r\n at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource1 retry, DbConnectionOptions userOptions)\r\n 在 System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource1 retry, DbConnectionOptions userOptions)\r\n at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource1 retry)\r\n 在 System.Data。 SqlClient.SqlConnection.TryOpen（TaskCompletionSource1 retry)\r\n at System.Data.SqlClient.SqlConnection.Open()\r\n at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.<Open>b__36(DbConnection t, DbConnectionInterceptionContext c)\r\n at System.Data.Entity.Infrastructure.Interception.InternalDispatcher1.Dispatch[TTarget,TInterceptionContext]（TTarget 目标，Action2 operation, TInterceptionContext interceptionContext, Action3 正在执行，Action3 executed)\r\n at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext)\r\n at System.Data.Entity.SqlServer.SqlProviderServices.<>c__DisplayClass34.<UsingConnection>b__32()\r\n at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()\r\n at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func1 操作）\r\n 在 System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy .Execute(Action 操作)\r\n at System.Data.Entity.SqlServer.SqlProviderServices.UsingConnection(DbConnection sqlConnection, Action1 act)\r\n at System.Data.Entity.SqlServer.SqlProviderServices.UsingMasterConnection(DbConnection sqlConnection, Action1 act)\r\n at System.Data.Entity.SqlServer.SqlProviderServices.DropDatabase(SqlConnection sqlConnection, Nullable1 commandTimeout, String databaseName)\r\n at System.Data.Entity.SqlServer.SqlProviderServices.DbDeleteDatabase(DbConnection connection, Nullable1 commandTimeout, StoreItemCollection storeItemCollection)\r\n 在 System.Data.Entity.Core.Common.DbProviderServices.DeleteDatabase(DbConnection 连接, Nullable@987654330 @1.InitializeDatabase(TContext 上下文)\r\n 在 System.Data.Entity.Internal.InternalContext.c__DisplayClassf1.<CreateInitializationAction>b__e()\r\n at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)\r\n at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization()\r\n at System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c)\r\n at System.Data.Entity.Internal.RetryAction1.PerformAction(TInput 输入)\r\n 在 System.Data.Entity.Internal.LazyInternalContext .InitializeDatabaseAction(Action1 action)\r\n at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase()\r\n at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)\r\n at System.Data.Entity.Internal.Linq.InternalSet1.Initialize()\r\n 在 System.Data.Entity.Internal.Linq.InternalSet1.get_InternalContext()\r\n at System.Data.Entity.Infrastructure.DbQuery1.System.Linq.IQueryable.get_Provider()\r\n 在 System.Linq .Queryable.Count[TSource](IQueryable`1 源)\r\n

Answer 1

我在你的堆栈中看到了这个：System.Data.Entity.DropCreateDatabaseIfModelChanges。我相信 EF 需要访问主数据库才能删除并重新创建您的数据库。

这篇博文提到了ClearDatabaseSchemaIfModelChanges 初始化器，它可以做你想做的事：http://blogs.msdn.com/b/azuremobile/archive/2014/06/07/fresh-updates-to-azure-mobile-services-net.aspx