Support clause on multiselection field with operator in and value None

Closes #14520
(grafted from 7a8606077f4c574566fe75d8b74573b31c934980)

--HG--
branch : 7.0

trytond/trytond/model/fields/multiselection.py

@@ -91,7 +91,9 @@ class MultiSelection(SelectionMixin, Field):
         database = Transaction().database
         table, _ = tables[None]
         raw_column = self.sql_column(table)
-        if isinstance(value, str):
+        if value is None:
+            expression = Literal(False)
+        elif isinstance(value, str):
             try:
                 expression = database.json_key_exists(raw_column, value)
             except NotImplementedError:

trytond/trytond/tests/test_field_multiselection.py

@@ -231,6 +231,32 @@ class FieldMultiSelectionTestCase(unittest.TestCase):
 
         self.assertEqual(selections, [selection])
 
+    @with_transaction()
+    def test_search_in_none(self):
+        "Test search selection in None"
+        Selection = Pool().get('test.multi_selection')
+        selection, = Selection.create([{
+                    'selects': ['foo', 'bar'],
+                    }])
+
+        result = Selection.search([
+                ('selects', 'in', None),
+                ])
+        self.assertEqual(result, [])
+
+    @with_transaction()
+    def test_search_not_in_none(self):
+        "Test search selection not in None"
+        Selection = Pool().get('test.multi_selection')
+        selection, = Selection.create([{
+                    'selects': ['foo', 'bar'],
+                    }])
+
+        result = Selection.search([
+                ('selects', 'not in', None),
+                ])
+        self.assertEqual(result, [selection])
+
     @with_transaction()
     def test_search_in_string(self):
         "Test search selection in string"