Question

Rather than maintaining a few different database access layers for OleDbConnection, MySqlConnection, OdbcConnection, and Db2Connection, I was trying to figure out a way to use generics. However, I get an error when I try to compile the code, I get errors when I try to access the class’s methods or properties.

public class DatabaseConnector<CONNECTION> {
    private CONNECTION connection = default(CONNECTION);
    public bool IsConnected {
        get {
            return (
                this.connection != null &&
                // error on connection.State on the following two lines
                this.connection.State != System.Data.ConnectionState.Closed &&
                this.connection.State != System.Data.ConnectionState.Broken
            );
        }
    }
}

Is there any way around this? Or perhaps another class that can handle the many versions?

Answer 1

You’re looking for constraints:

public class DatabaseConnector<TConnection> where TConnection : DbConnection, new() {