Question

I have a generic method to call a stored Procedure in ASP.NET:

public SqlDataReader ExecuteStoredProc(string sprocName, SqlParameter[] SqlP)
        {
            SqlDataReader iReader;
            SqlCommand sql = new SqlCommand();

            sql.CommandText = sprocName;
            sql.CommandType = CommandType.StoredProcedure;
            sql.Connection = ConnStr;
            if (SqlP != null)
            {
                foreach (SqlParameter p in SqlP)
                {
                    sql.Parameters.Add(p);
                }

            }
            sql.Connection.Open();
            iReader = sql.ExecuteReader(CommandBehavior.CloseConnection);
            sql.Dispose();

            return iReader;
        }

Even though I am calling CommandBehavior.CloseConnection the connection is not closing. I can get the data fine the first time I request a page. On reload I get the following error:

The connection was not closed. The
connection’s current state is open.
Description: An unhandled exception
occurred during the execution of the
current web request. Please review the
stack trace for more information about
the error and where it originated in
the code.

Exception Details:
System.InvalidOperationException: The
connection was not closed. The
connection’s current state is open.

Source Error:

Line 35: Line 36: } Line
37: sql.Connection.Open();
Line 38: iReader =
sql.ExecuteReader(CommandBehavior.CloseConnection);
Line 39: sql.Dispose();

Finally if I put sql.Connection.Close(); before sql.Dispose(); I get an error that iReader is not readable because it’s been closed already.

Obviously I am closing my connection incorrectly, can someone point me in the right direction?

Answer 1

When you return a DataReader, the underlying connection must remain open. It’s the consumer’s responsibility to properly clean up resources.

public SqlDataReader ExecuteStoredProc(string sprocName, SqlParameter[] SqlP)
{
    SqlCommand sql = new SqlCommand();

    sql.CommandText = sprocName;
    sql.CommandType = CommandType.StoredProcedure;
    sql.Connection = ConnStr;
    if (SqlP != null)
    {
        foreach (SqlParameter p in SqlP)
        {
            sql.Parameters.Add(p);
        }

    }
    sql.Connection.Open();
    return sql.ExecuteReader(CommandBehavior.CloseConnection);          
}

public void ConsumingMethod()
{
    using(SqlDataReader reader = ExecuteStoredProc("MyProc", params))
    {
        while(reader.Read())
        {
            //work with your reader
        }
    }
}