I'm on Odoo 9.0 and trying to inherit from stock.picking which has the Delivery module inheriting from it. The Delivery module adds a field named "carrier_id". I need to inherit and add a field named "carrier_service". When I override the create method in order to calculate a value for my new field I need to reference "carrier_id", but it's not in the dictionary of values passed to my create method resulting in a key error.

How can I do this? Code below;

class StockPicking(models.Model):
    _inherit = "stock.picking"
    carrier_service = fields.Char(string='Carrier Service')
    
    @api.model
    def create(self, values):
        carrier_mapping = (self.env["integration.carrier_mapping"].search([("delivery_method_id.id", "=", values['carrier_id'])])
        values['carrier_service']=carrier_mapping.service
        return super(StockPicking, self).create(values)