Magento $ collection-> join - Multiple

Question

I'm currently extending the Magento Invoice Grid to display some additional columns. I've got the data that I need for most, but I'm struggling to get more than 1 Column from the same Database Table.

This is what I have in my _prepareCollection

$collection->join('invoice','main_table.entity_id=invoice.entity_id','subtotal');
$collection->join('invoice','main_table.entity_id=invoice.entity_id','discount_description');

I assume I need to drop the second line and put them into somekind of array, I'm just not sure on how to do that as I don't work with PHP too much.

Thanks.

Answer 1

Oh, this was much more simple than I was expecting, I managed to work it out with the following:

    $collection->join('invoice', 'main_table.entity_id = invoice.entity_id', array(
        'subtotal',
        'discount_description'
    ));