Cause of the error

Why Xcode shows you an error like below even if you set the DatabaseIdentifier properly.

Member 'mysql' in 'DatabaseIdentifier<>' produces result of type 'DatabaseIdentifier', but context expects 'DatabaseIdentifier<>'

Causes are

• Something wrong the code inside of closure.
• No code inside of closure yet.

So, if you write code properly inside the closure, the error will be gone.

Patterns with the error.

let result = context.container.withNewConnection(to: .mysql){
    conn in            
}

let result = context.container.withNewConnection(to: .mysql){
    conn in
    return 1            
}

etc.

Patterns without the error.

let result = context.container.withNewConnection(to: .mysql){
    conn in            
    return conn.raw("select * from talbeA;").all()
}

Xcode might not be able to show the error properly if the code inside the closure is wrong. I spent a lot of time because of this error😭 I hope this article helps someone like me.