I want the Price_list field to keep the fixed_price value from the product_pricelist_item of the product in the invoice, but from my code. The value is 0. How should I fix a fixed_price value from a product_pricelist_item of a product stored in a field? Thanks for the help.
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class AccountInvoiceLine(models.Model):

  _inherit = 'account.invoice.line'

price_list = fields.Float('fixed_price ',compute='get_commission')

@api.multi

def get_commission(self):

self. price_list =  self.env.cr.execute\

("SELECT a.fixed_price FROM product_pricelist_item a"

"WHERE a.pricelist_id=2 AND a.product_id=%s",

(self.product_id.id,))