[IMP] stock: show related products on duplicated barcode

Previously, product barcodes uniqueness was enforced
by a SQL constraint, resulting in a generic error message.

The SQL constraint has been replaced by a Python check,
which allows the listing of conflicting barcodes in the
error message, including those resulting from batch edits.

Task: 2654703-7
Part-of: odoo/odoo#84056

addons/product/models/product_product.py

@@ -2,6 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 import re
+from operator import itemgetter
 
 from odoo import api, fields, models, tools, _
 from odoo.exceptions import ValidationError
@@ -168,9 +169,35 @@ class ProductProduct(models.Model):
         self.env.cr.execute("CREATE UNIQUE INDEX IF NOT EXISTS product_product_combination_unique ON %s (product_tmpl_id, combination_indices) WHERE active is true"
             % self._table)
 
-    _sql_constraints = [
-        ('barcode_uniq', 'unique(barcode)', "A barcode can only be assigned to one product !"),
-    ]
+    @api.constrains("barcode")
+    def _check_barcode_unique(self):
+
+        # Collect `product.product.id` of objects that share a barcode with any of those in `self`,
+        # and group them by barcode.
+        candidate_duplicates = self.env['product.product'].sudo().read_group(
+            domain=[("barcode", "in", list(set(product.barcode for product in self if product.barcode)))],
+            fields=['ids:array_agg(id)', 'barcode'],
+            groupby=['barcode']
+        )
+
+        # Keep only barcodes that match more than one `product.product` object.
+        duplicates = [candidate for candidate in candidate_duplicates if candidate['barcode_count'] > 1]
+        if duplicates:
+            # Prepare a mapping of "{ `product.barcode`: [`product.display_name`, ... ] }" to show the user.
+            duplicates_joined = {dup['barcode']: ', '.join(
+                sorted([product.display_name for product in
+                        self.env['product.product'].browse(dup['ids'])])
+            ) for dup in sorted(duplicates, key=itemgetter('barcode'))}
+
+            # Transform the mapping into a prettified string and raise.
+            duplicates_as_str = "\n".join(
+                f"Barcode \"{barcode}\" already assigned to product(s): {products}"
+                for barcode, products in duplicates_joined.items()
+            )
+
+            raise ValidationError(
+                "Barcode(s) already assigned:\n\n{duplicates}".format(duplicates=duplicates_as_str)
+            )
 
     @api.constrains('barcode')
     def _check_barcode_uniqueness(self):

addons/product/tests/__init__.py

@@ -7,3 +7,4 @@ from . import test_pricelist
 from . import test_product_pricelist
 from . import test_seller
 from . import test_product_attribute_value_config
+from . import test_barcode

addons/product/tests/test_barcode.py

@@ -0,0 +1,55 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import exceptions
+from odoo.tests.common import TransactionCase
+
+
+class TestProductBarcode(TransactionCase):
+
+    def setUp(self):
+        super().setUp()
+        self.env['product.product'].create({'name': 'BC1', 'barcode': '1'})
+        self.env['product.product'].create({'name': 'BC2', 'barcode': '2'})
+
+    def test_blank_barcodes_allowed(self):
+        """Makes sure duplicated blank barcodes are allowed."""
+        for i in range(2):
+            self.env['product.product'].create({'name': f'BC_{i}'})
+
+    def test_false_barcodes_allowed(self):
+        """Makes sure duplicated False barcodes are allowed."""
+        for i in range(2):
+            self.env['product.product'].create({'name': f'BC_{i}', 'barcode': False})
+
+    def test_duplicated_barcode(self):
+        """Tests for simple duplication."""
+        with self.assertRaises(exceptions.ValidationError):
+            self.env['product.product'].create({'name': 'BC3', 'barcode': '1'})
+
+    def test_duplicated_barcode_in_batch_edit(self):
+        """Tests for duplication in batch edits."""
+        batch = [
+            {'name': 'BC3', 'barcode': '3'},
+            {'name': 'BC4', 'barcode': '4'},
+        ]
+        self.env['product.product'].create(batch)
+        batch.append({'name': 'BC5', 'barcode': '1'})
+        with self.assertRaises(exceptions.ValidationError):
+            self.env['product.product'].create(batch)
+
+    def test_test_duplicated_barcode_error_msg_content(self):
+        """Validates the error message shown when duplicated barcodes are found."""
+        batch = [
+            {'name': 'BC3', 'barcode': '3'},
+            {'name': 'BC4', 'barcode': '3'},
+            {'name': 'BC5', 'barcode': '4'},
+            {'name': 'BC6', 'barcode': '4'},
+            {'name': 'BC7', 'barcode': '1'},
+        ]
+        try:
+            self.env['product.product'].create(batch)
+        except exceptions.ValidationError as exc:
+            assert 'Barcode "3" already assigned to product(s): BC3, BC4' in exc.args[0]
+            assert 'Barcode "4" already assigned to product(s): BC5, BC6' in exc.args[0]
+            assert 'Barcode "1" already assigned to product(s): BC1' in exc.args[0]