如何创建从.NET服务到远程PostgreSQL服务器的连接

Question

我无法使用某些连接字符串从C#.NET代码连接到远程PostgreSQL服务器。（我的连接字符串包含基本信息，如主机地址，端口，用户名，密码，数据库名）。

我的连接字符串:server=host_address；port=host_port；用户id=postgres_username；password=postgres_password；database=postgres_database_name；

注意：我使用的是npgsql.NET程序集

我得到的错误是：

No connection could be made because the target machine actively refused it
 Npgsql.NpgsqlConnector.Connect(NpgsqlTimeout timeout)
   at Npgsql.NpgsqlConnector.<RawOpen>d__153.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnector.<Open>d__149.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.ConnectorPool.<AllocateLong>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnection.<>c__DisplayClass32_0.<<Open>g__OpenLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnection.Open()

Answer 1

在我看来，您试图连接的机器可能有端口阻塞，请检查是否是这样。如果不是，则可以按照Npsql文档（https://www.npgsql.org/doc/index.html）中的语法检查字符串连接，如下所示：

var connString = "Host=myserver;Username=mylogin;Password=mypass;Database=mydatabase";

在这里可以找到连接字符串参数。