How to select specific fields with aliases using joinTable or joinField in Magento

Question

I want to pre-filter* data in the invoice grid visible in Magento\'s admin panel.

Here is a question that I asked earlier, and this one is related to the solution prese

Answer 1

The error "A joint field with this alias (0) is already declared." occurs because it uses array keys as aliases. Since you have two joinTable() calls, each with an array, it is trying to use the zero-based index of both and obviously having a conflict.
So instead of

array('entity_id as order_entity_id')

try

array('entity_id' => 'order_entity_id')

to avoid the conflict.