Do not convert select query value into list when searching on char with in operator

Closes #14898
(grafted from f62e20c70717ed0a40ad86a7dd5672577f73626b)

--HG--
branch : 8.0

trytond/trytond/model/fields/char.py

@@ -3,7 +3,7 @@
 import string
 import warnings
 
-from sql import Column, Expression, Query
+from sql import Column, CombiningQuery, Expression, Query, Select
 from sql.conditionals import Coalesce, NullIf
 from sql.functions import Trim
 from sql.operators import Not
@@ -121,10 +121,11 @@ class Char(FieldTranslate):
         return column
 
     def _domain_value(self, operator, value):
-        if operator in {'in', 'not in'}:
-            value = [v if v is not None else '' for v in value]
-        elif value is None:
-            value = ''
+        if not isinstance(value, (Select, CombiningQuery)):
+            if operator in {'in', 'not in'}:
+                value = [v if v is not None else '' for v in value]
+            elif value is None:
+                value = ''
         value = super()._domain_value(operator, value)
         if self.search_unaccented and operator.endswith('ilike'):
             database = Transaction().database

trytond/trytond/tests/test_field_char.py

@@ -3,7 +3,7 @@
 # this repository contains the full copyright notices and license terms.
 import unittest
 
-from sql import Literal
+from sql import Literal, Select
 
 from trytond import backend
 from trytond.model.exceptions import (
@@ -55,9 +55,17 @@ class CommonTestCaseMixin:
         chars_bar = Char.search([
                 ('char', '=', "Bar"),
                 ])
+        chars_select_foo = Char.search([
+                ('char', '=', Select([Literal('Foo')])),
+                ])
+        chars_select_bar = Char.search([
+                ('char', '=', Select([Literal('Bar')])),
+                ])
 
         self.assertListEqual(chars_foo, [char])
         self.assertListEqual(chars_bar, [])
+        self.assertListEqual(chars_select_foo, [char])
+        self.assertListEqual(chars_select_bar, [])
 
     @with_transaction()
     def test_search_equals_none(self):
@@ -178,10 +186,18 @@ class CommonTestCaseMixin:
         chars_empty = Char.search([
                 ('char', 'in', []),
                 ])
+        chars_select_foo = Char.search([
+                ('char', 'in', Select([Literal('Foo')])),
+                ])
+        chars_select_bar = Char.search([
+                ('char', 'in', Select([Literal('Bar')])),
+                ])
 
         self.assertListEqual(chars_foo, [char])
         self.assertListEqual(chars_bar, [])
         self.assertListEqual(chars_empty, [])
+        self.assertListEqual(chars_select_foo, [char])
+        self.assertListEqual(chars_select_bar, [])
 
     @with_transaction()
     def test_search_in_none(self):