实体框架,代码优先:避免与天蓝色主数据库的不必要连接

Question

当EF尝试连接到Azure sql数据库时(可能在尝试打开与数据库的连接时,不确定)它会尝试连接/登录到master数据库,问题是为什么？

连接字符串上的用户不允许连接到master数据库,从我可以看到记录的内容,EF尝试用户未能成功登录master数据库时出现错误,但功能上应用程序正常工作(该应用程序不需要访问master db做任何事情).

从我的研究看来,它似乎与这个问题最相似,但是这已经被关闭,因为不可重复,并且不确定在尝试获取ProviderManifestToken时是否会发生这种情况.

因此,如果数据库用户对数据库具有所需权限,并且连接字符串反映了这一点,那么为什么EF会尝试连接到master数据库？

上下文的示例连接字符串

Server=tcp:MyServer;Database=MyDb;User ID=MyDatabaseUser;Password=*****;Trusted_Connection=False;Encrypt=True;Connection Timeout=30;TrustServerCertificate=False;

记录以下错误消息:

15-05-07 04:06:16.404 System.Data.SqlClient.SqlException (0x80131904): The server principal "MyDatabaseUser" is not able to access the database "master" under the current security context.
Database 'master' on server 'MyServer' is not currently available.  Please retry the connection later.  If the problem persists, contact customer support, and provide them the session tracing ID of '69955F47-7746-41560-A03C-807FB9A56478A'.
Login failed for user 'MyDatabaseUser'.
   at System.Data.SqlClient.SqlInternalConnection.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.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK)
   at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)
   at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)
   at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)
   at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData)
   at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext](TTarget target, Action`2 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
   at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext)
   at System.Data.Entity.SqlServer.SqlProviderServices.<>c__DisplayClass33.<UsingConnection>b__32()
   at System.Data.Entity.Infrastructure.DbExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
   at System.Data.Entity.Infrastructure.DbExecutionStrategy.Execute[TResult](Func`1 operation)
ClientConnectionId:5a5e2892-0d1f-471c-a1b7-5f9e5705655f1
ErrorCode: 916
ErrorCode: 40613
ErrorCode: 18456

Answer 1

实体框架正在尝试连接到master数据库,因为Code First会尝试为项目创建数据库(如果该数据库不存在).这只能通过以下方式完成master.

您仍然可以使用Code First并对现有数据库进行操作,但您至少需要更改设置,以便不会尝试创建数据库.您可以将其设置为更新,这没关系.我个人的偏好是关闭所有数据库管理,并自己处理它.

这是通过在DbContext上创建静态重载构造函数来完成的:

public static MyContext() : base(null) {}

此链接讨论可用的不同数据库初始值设定项.上面的静态构造函数不会创建初始化程序.这是另一个讨论相同初始化程序以及创建自定义程序的链接.