[FIX] mrp_unbuild_subcontracting: Cannot unbuild subcontracting orders with many links

From version 16.0, when we create backorders we are not splitting the Origin Moves. For that reason, when we try to unbuild a subcontracting order that has more than origin move we cannot know which is the real origin.

There has been a PR to fix this in Odoo here: https://github.com/odoo/odoo/pull/148262, but it was reverted after some time due to some problems on the splitting. If we want to allow this, we would need to propose a PR in Odoo that completely fixes this problem.

mrp_unbuild_subcontracting/models/stock_picking.py

@@ -1,6 +1,7 @@
 from datetime import timedelta
 
-from odoo import fields, models
+from odoo import _, fields, models
+from odoo.exceptions import UserError
 from odoo.osv.expression import OR
 
 
@@ -14,6 +15,18 @@ class StockPicking(models.Model):
     def _prepare_subcontract_unbuild_vals(self, subcontract_move, bom):
         subcontract_move.ensure_one()
         product = subcontract_move.product_id
+        mos = subcontract_move.mapped(
+            "origin_returned_move_id.move_orig_ids.production_id"
+        )
+        if len(mos) > 1:
+            raise UserError(
+                _(
+                    "It's not possible to create the subcontracting unbuild order\n"
+                    "The subcontract move %(smn)s is linked with more than "
+                    "one manufacturing order: %(jmm)s"
+                )
+                % {"smn": subcontract_move.name, "jmm": ",".join(mos.mapped("name"))}
+            )
         vals = {
             "company_id": subcontract_move.company_id.id,
             "product_id": product.id,
@@ -28,7 +41,7 @@ class StockPicking(models.Model):
             "product_qty": subcontract_move.product_uom_qty,
             "picking_id": self.id,
             "is_subcontracted": True,
-            "mo_id": subcontract_move.move_orig_ids.move_orig_ids.production_id.id,
+            "mo_id": mos.id,
             "lot_id": subcontract_move.move_orig_ids.lot_ids.id,
         }
         return vals

mrp_unbuild_subcontracting/tests/test_mrp_unbuild_subcontracting.py

@@ -1,3 +1,4 @@
+from odoo.exceptions import UserError
 from odoo.tests import Form, TransactionCase
 
 
@@ -207,17 +208,21 @@ class TestSubcontractingPurchaseFlows(TransactionCase):
             )
         )
         return_wizard._onchange_picking_id()
-        return_id, _ = return_wizard._create_returns()
+        with self.assertRaises(UserError):
+            return_id, _ = return_wizard._create_returns()
 
-        return_picking = self.env["stock.picking"].browse(return_id)
-        return_picking.move_ids.quantity_done = 3
-        return_picking.button_validate()
-
-        self.assertEqual(po.order_line.qty_received, 6)
-
-        mo = picking_to_return.mapped("move_ids.move_orig_ids.production_id")
-        unbuild = self.env["mrp.unbuild"].search([("mo_id", "in", mo.ids)])
-        self.assertTrue(unbuild.exists())
+        # This part cannot be tested since we cannot unbuild
+        # subcontracting orders with more than one origin.
+        #
+        # return_picking = self.env["stock.picking"].browse(return_id)
+        # return_picking.move_ids.quantity_done = 3
+        # return_picking.button_validate()
+        #
+        # self.assertEqual(po.order_line.qty_received, 6)
+        #
+        # mo = picking_to_return.mapped("move_ids.move_orig_ids.production_id")
+        # unbuild = self.env["mrp.unbuild"].search([("mo_id", "in", mo.ids)])
+        # self.assertTrue(unbuild.exists())
 
 
 class TestSubcontractingTracking(TransactionCase):