Question

I have the following code that is being copied and pasted in a number of places. The only difference being that there is a single call in the middle of the usings which changes. So I made a

public MyEntity Read(int id)
{
    using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
    {
        sqlConn.Open();
        return MyDataLayer.Select(sqlConn, id);
    }
}

So I came up with this. However, my problem is how do i pass the sqlConn var to the call?

public TResult UsingSqlConnection<TResult>(Func<TResult> myFunction)
{
    using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
    {
        sqlConn.Open();
        return myFunction();
    }
}

public MyEntity Read(int id)
{
    return UsingSqlConnection(() => MyDataLayer.Read(id)); 
   //PROBLEM: Read() requires sqlConn
}

Off the top of my head – it looks like instead of passing it as a param, that I need to create a property for SqlConn in MyDataLayer and assign it in the UsingSqlConnection method using an interface. While i wont rule out that refactor, I am wondering if I am missing something as this is my first attempt with Func delegates in this way.

Answer 1

Func can have parameters:

public TResult UsingSqlConnection<TResult>(Func<SqlConnection, TResult> myFunc)
{
    using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
    {
        sqlConn.Open();
        return myFunc(sqlConn);
    }
}

public MyEntity Read(int id)
{
    return UsingSqlConnection((sqlConn) => MyDataLayer.Read(sqlConn, id));       
}