[IMP] sale_purchase: give the possibility to inject a partner

closes odoo/odoo#131186

Signed-off-by: William Henrotin (whe) <whe@odoo.com>

addons/sale_purchase/models/sale_order_line.py

@@ -194,6 +194,12 @@ class SaleOrderLine(models.Model):
             'sale_line_id': self.id,
         }
 
+    def _retrieve_purchase_partner(self):
+        """ In case we want to explicitely name a partner from whom we want to buy or receive products
+        """
+        self.ensure_one()
+        return False
+
     def _purchase_service_create(self, quantity=False):
         """ On Sales Order confirmation, some lines (services ones) can create a purchase order line and maybe a purchase order.
             If a line should create a RFQ, it will check for existing PO. If no one is find, the SO line will create one, then adds
@@ -206,7 +212,7 @@ class SaleOrderLine(models.Model):
         for line in self:
             line = line.with_company(line.company_id)
             # determine vendor of the order (take the first matching company and product)
-            suppliers = line.product_id._select_seller(quantity=line.product_uom_qty, uom_id=line.product_uom)
+            suppliers = line.product_id._select_seller(partner_id=line._retrieve_purchase_partner(), quantity=line.product_uom_qty, uom_id=line.product_uom)
             if not suppliers:
                 raise UserError(_("There is no vendor associated to the product %s. Please define a vendor for this product.") % (line.product_id.display_name,))
             supplierinfo = suppliers[0]