contract/contract_sale_mandate/models/sale_order.py

# Copyright 2019 ACSONE SA/NV
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).

from odoo import api, models


class SaleOrder(models.Model):
    _inherit = 'sale.order'

    @api.multi
    def _prepare_contract_value(self, contract_template):
        self.ensure_one()
        vals = super(SaleOrder, self)._prepare_contract_value(
            contract_template)
        vals['mandate_id'] = self.mandate_id.id
        return vals