[IMP] base: support group_expand for custom fields

Allow a naive `group_expand` for manual fields where having the
attribute set to True causes the ORM to include all records from the
relation model of the m2o field in the read_group.

This is particularly useful for custom m2o fields which represent
stages - a grouped list view or a kanban view should include all
possible stage, not only the currently used values.

Co-Authored-By: Raphaël Collet <rco@odoo.com>

odoo/addons/base/models/ir_model.py

@@ -397,6 +397,12 @@ class IrModelFields(models.Model):
                                             "specified as a Python expression defining a list of triplets. "
                                             "For example: [('color','=','red')]")
     groups = fields.Many2many('res.groups', 'ir_model_fields_group_rel', 'field_id', 'group_id') # CLEANME unimplemented field (empty table)
+    group_expand = fields.Boolean(string="Expand Groups",
+                                  help="If checked, all the records of the target model will be included\n"
+                                        "in a grouped result (e.g. 'Group By' filters, Kanban columns, etc.).\n"
+                                        "Note that it can significantly reduce performance if the target model\n"
+                                        "of the field contains a lot of records; usually used on models with\n"
+                                        "few records (e.g. Stages, Job Positions, Event Types, etc.).")
     selectable = fields.Boolean(default=True)
     modules = fields.Char(compute='_in_modules', string='In Apps', help='List of modules in which the field is defined')
     relation_table = fields.Char(help="Used for custom many2many fields to define a custom relation table name")
@@ -994,6 +1000,7 @@ class IrModelFields(models.Model):
             attrs['comodel_name'] = field_data['relation']
             attrs['ondelete'] = field_data['on_delete']
             attrs['domain'] = safe_eval(field_data['domain'] or '[]')
+            attrs['group_expand'] = '_read_group_expand_full' if field_data['group_expand'] else None
         elif field_data['ttype'] == 'one2many':
             if not self.pool.loaded and not (
                 field_data['relation'] in self.env and (

odoo/addons/base/tests/test_ir_model.py

@@ -186,6 +186,19 @@ class TestIrModel(SavepointCase):
         cls.registry.enter_test_mode(cls.cr)
         cls.addClassCleanup(cls.registry.leave_test_mode)
 
+        # model and records for banana stages
+        cls.env['ir.model'].create({
+            'name': 'Banana Ripeness',
+            'model': 'x_banana_ripeness',
+            'field_id': [
+                (0, 0, {'name': 'x_name', 'ttype': 'char', 'field_description': 'Name'}),
+            ]
+        })
+        # stage values are pairs (id, display_name)
+        cls.ripeness_green = cls.env['x_banana_ripeness'].name_create('Green')
+        cls.ripeness_okay = cls.env['x_banana_ripeness'].name_create('Okay, I guess?')
+        cls.ripeness_gone = cls.env['x_banana_ripeness'].name_create('Walked away on its own')
+
         # model and records for bananas
         cls.bananas_model = cls.env['ir.model'].create({
             'name': 'Bananas',
@@ -194,6 +207,9 @@ class TestIrModel(SavepointCase):
                 (0, 0, {'name': 'x_name', 'ttype': 'char', 'field_description': 'Name'}),
                 (0, 0, {'name': 'x_length', 'ttype': 'float', 'field_description': 'Length'}),
                 (0, 0, {'name': 'x_color', 'ttype': 'integer', 'field_description': 'Color'}),
+                (0, 0, {'name': 'x_ripeness_id', 'ttype': 'many2one',
+                        'field_description': 'Ripeness','relation': 'x_banana_ripeness',
+                        'group_expand': True})
             ]
         })
         # add non-stored field that is not valid in order
@@ -206,6 +222,8 @@ class TestIrModel(SavepointCase):
             'depends': 'x_color',
             'compute': "for banana in self:\n    banana['x_is_yellow'] = banana.x_color == 9"
         })
+        # default stage is ripeness_green
+        cls.env['ir.default'].set('x_bananas', 'x_ripeness_id', cls.ripeness_green[0])
         cls.env['x_bananas'].create([{
             'x_name': 'Banana #1',
             'x_length': 3.14159,
@@ -271,3 +289,23 @@ class TestIrModel(SavepointCase):
 
             bananas = self.env['x_bananas'].search([])
             self.assertEqual(bananas.mapped('x_name'), names, 'failed to order by %s' % order)
+
+    def test_group_expansion(self):
+        """Check that the basic custom group expansion works."""
+        groups = self.env['x_bananas'].read_group(domain=[],
+                                                  fields=['x_ripeness_id'],
+                                                  groupby=['x_ripeness_id'])
+        expected = [{
+            'x_ripeness_id': self.ripeness_green,
+            'x_ripeness_id_count': 3,
+            '__domain': [('x_ripeness_id', '=', self.ripeness_green[0])],
+        }, {
+            'x_ripeness_id': self.ripeness_okay,
+            'x_ripeness_id_count': 0,
+            '__domain': [('x_ripeness_id', '=', self.ripeness_okay[0])],
+        }, {
+            'x_ripeness_id': self.ripeness_gone,
+            'x_ripeness_id_count': 0,
+            '__domain': [('x_ripeness_id', '=', self.ripeness_gone[0])],
+        }]
+        self.assertEqual(groups, expected, 'should include 2 empty ripeness stages')

odoo/addons/base/views/ir_model_views.xml

@@ -274,6 +274,9 @@
                                             attrs="{'required': [('ttype','in',['many2one','one2many','many2many'])],
                                                     'readonly': [('ttype','not in',['many2one','one2many','many2many'])],
                                                     'invisible': [('ttype','not in',['many2one','one2many','many2many'])]}"/>
+                                        <field name="group_expand" groups="base.group_no_one"
+                                            attrs="{'readonly': [('ttype','!=','many2one')],
+                                                    'invisible': [('ttype','!=','many2one')]}"/>
                                         <field name="on_delete" groups="base.group_no_one"
                                             attrs="{'readonly': [('ttype','!=','many2one')],
                                                     'invisible': [('ttype','!=','many2one')]}"/>

odoo/models.py

@@ -1754,6 +1754,11 @@ class BaseModel(MetaModel('DummyModel', (object,), {'_register': False})):
         """
         cls.pool._clear_cache()
 
+    @api.model
+    def _read_group_expand_full(self, groups, domain, order):
+        """Extend the group to include all targer records by default."""
+        return groups.search([], order=order)
+
     @api.model
     def _read_group_fill_results(self, domain, groupby, remaining_groupbys,
                                  aggregated_fields, count_field,