Hi ! Here is an old api code from the sale_margin module:

class sale_order(osv.osv):

    _inherit = "sale.order"

    def _product_margin(self, cr, uid, ids, field_name, arg, context=None):

        result = {}

        for sale in self.browse(cr, uid, ids, context=context):

            result[sale.id] = 0.0

            for line in sale.order_line:

                if line.state == 'cancel':

                    continue

                result[sale.id] += line.margin or 0.0

        return result

    def _get_order(self, cr, uid, ids, context=None):

        result = {}

        for line in self.pool.get('sale.order.line').browse(cr, uid, ids, context=context):

            result[line.order_id.id] = True

        return result.keys()

    _columns = {

        'margin': fields.function(_product_margin, string='Margin', help="It gives profitability by calculating the difference between the Unit Price and the cost price.", store={

                'sale.order.line': (_get_order, ['margin', 'purchase_price', 'order_id'], 20),

                'sale.order': (lambda self, cr, uid, ids, c={}: ids, ['order_line'], 20),

                }, digits_compute= dp.get_precision('Product Price')),

    }

I just can't understand what the code in bold means. Could someone explain what it does imply ?

Is it just storing the computed field inside the db ? And why a store=True kwarg wouldn't be sufficient ?

For various reasons, I need to override the margin computed field. How can I do it since it seems to be quite special case?