[FIX] fields, test_new_api: monetary related custom

This commit allows for not copying the currency_field attribute
of a monetary field when the monetary field is related,
and when the currency_field attribute is not explicit

Before this commit, the currency_field attribute on the related monetary
was set as the one on the distant model

After this commit, the currency_field attribute takes the field on the
current model

Though the test may appear like an incoherent use case,
it is on the contrary totally legit, as web_studio allows it

OPW 1903113

closes odoo/odoo#28144

5 files changed, 71 insertions, 4 deletions

diff --git a/odoo/addons/test_new_api/ir.model.access.csv b/odoo/addons/test_new_api/ir.model.access.csv
index c825fb51c59..77c881dcc4d 100644
--- a/odoo/addons/test_new_api/ir.model.access.csv
+++ b/odoo/addons/test_new_api/ir.model.access.csv
@@ -22,3 +22,7 @@ access_test_new_api_multi_compute_inverse,access_test_new_api_multi_compute_inve
 access_test_new_api_recursive,access_test_new_api_recursive,model_test_new_api_recursive,,1,1,1,1
 access_test_new_api_cascade,access_test_new_api_cascade,model_test_new_api_cascade,,1,1,1,1
 access_test_new_api_binary_svg,access_test_new_api_binary_svg,model_test_new_api_binary_svg,,1,1,1,1
+access_test_new_api_monetary_base,access_test_new_api_monetary_base,model_test_new_api_monetary_base,,1,1,1,1
+access_test_new_api_monetary_related,access_test_new_api_monetary_related,model_test_new_api_monetary_related,,1,1,1,1
+access_test_new_api_monetary_custom,access_test_new_api_monetary_custom,model_test_new_api_monetary_custom,,1,1,1,1
+access_test_new_api_monetary_inherits,access_test_new_api_monetary_inherits,model_test_new_api_monetary_inherits,,1,1,1,1
diff --git a/odoo/addons/test_new_api/models.py b/odoo/addons/test_new_api/models.py
index 043ee8a0b7d..7d7ad777b44 100644
--- a/odoo/addons/test_new_api/models.py
+++ b/odoo/addons/test_new_api/models.py
@@ -468,3 +468,38 @@ class BinarySvg(models.Model):
     name = fields.Char(required=True)
     image_attachment = fields.Binary(attachment=True)
     image_wo_attachment = fields.Binary(attachment=False)
+
+
+class MonetaryBase(models.Model):
+    _name = 'test_new_api.monetary_base'
+    _description = 'Monetary Base'
+
+    base_currency_id = fields.Many2one('res.currency')
+    amount = fields.Monetary(currency_field='base_currency_id')
+
+
+class MonetaryRelated(models.Model):
+    _name = 'test_new_api.monetary_related'
+    _description = 'Monetary Related'
+
+    monetary_id = fields.Many2one('test_new_api.monetary_base')
+    currency_id = fields.Many2one('res.currency', related='monetary_id.base_currency_id')
+    amount = fields.Monetary(related='monetary_id.amount')
+
+
+class MonetaryCustom(models.Model):
+    _name = 'test_new_api.monetary_custom'
+    _description = 'Monetary Related Custom'
+
+    monetary_id = fields.Many2one('test_new_api.monetary_base')
+    x_currency_id = fields.Many2one('res.currency', related='monetary_id.base_currency_id')
+    x_amount = fields.Monetary(related='monetary_id.amount')
+
+
+class MonetaryInherits(models.Model):
+    _name = 'test_new_api.monetary_inherits'
+    _description = 'Monetary Inherits'
+    _inherits = {'test_new_api.monetary_base': 'monetary_id'}
+
+    monetary_id = fields.Many2one('test_new_api.monetary_base', required=True, ondelete='cascade')
+    currency_id = fields.Many2one('res.currency')
diff --git a/odoo/addons/test_new_api/tests/test_new_fields.py b/odoo/addons/test_new_api/tests/test_new_fields.py
index caa4eedf4bf..9b3da038c5c 100644
--- a/odoo/addons/test_new_api/tests/test_new_fields.py
+++ b/odoo/addons/test_new_api/tests/test_new_fields.py
@@ -1054,6 +1054,26 @@ class TestFields(common.TransactionCase):
         ])
         self.assertEqual(attachment.mimetype, 'text/plain')
 
+    def test_93_monetary_related(self):
+        """ Check the currency field on related monetary fields. """
+        # check base field
+        field = self.env['test_new_api.monetary_base']._fields['amount']
+        self.assertEqual(field.currency_field, 'base_currency_id')
+
+        # related fields must use the field 'currency_id' or 'x_currency_id'
+        field = self.env['test_new_api.monetary_related']._fields['amount']
+        self.assertEqual(field.related, ('monetary_id', 'amount'))
+        self.assertEqual(field.currency_field, 'currency_id')
+
+        field = self.env['test_new_api.monetary_custom']._fields['x_amount']
+        self.assertEqual(field.related, ('monetary_id', 'amount'))
+        self.assertEqual(field.currency_field, 'x_currency_id')
+
+        # inherited field must use the same field as its parent field
+        field = self.env['test_new_api.monetary_inherits']._fields['amount']
+        self.assertEqual(field.related, ('monetary_id', 'amount'))
+        self.assertEqual(field.currency_field, 'base_currency_id')
+
 
 class TestX2many(common.TransactionCase):
     def test_search_many2many(self):
diff --git a/odoo/fields.py b/odoo/fields.py
index a146a1bfa07..00923886d0a 100644
--- a/odoo/fields.py
+++ b/odoo/fields.py
@@ -1276,11 +1276,9 @@ class Monetary(Field):
     def __init__(self, string=Default, currency_field=Default, **kwargs):
         super(Monetary, self).__init__(string=string, currency_field=currency_field, **kwargs)
 
-    _related_currency_field = property(attrgetter('currency_field'))
     _description_currency_field = property(attrgetter('currency_field'))
 
-    def _setup_regular_full(self, model):
-        super(Monetary, self)._setup_regular_full(model)
+    def _setup_currency_field(self, model):
         if not self.currency_field:
             # pick a default, trying in order: 'currency_id', 'x_currency_id'
             if 'currency_id' in model._fields:
@@ -1290,6 +1288,16 @@ class Monetary(Field):
         assert self.currency_field in model._fields, \
             "Field %s with unknown currency_field %r" % (self, self.currency_field)
 
+    def _setup_regular_full(self, model):
+        super(Monetary, self)._setup_regular_full(model)
+        self._setup_currency_field(model)
+
+    def _setup_related_full(self, model):
+        super(Monetary, self)._setup_related_full(model)
+        if self.inherited:
+            self.currency_field = self.related_field.currency_field
+        self._setup_currency_field(model)
+
     def convert_to_column(self, value, record, values=None, validate=True):
         # retrieve currency from values or record
         if values and self.currency_field in values:
diff --git a/odoo/tests/common.py b/odoo/tests/common.py
index 55fad1ceb73..39bb02ab717 100644
--- a/odoo/tests/common.py
+++ b/odoo/tests/common.py
@@ -314,7 +314,7 @@ class BaseCase(TreeCase, MetaCase('DummyCase', (object,), {})):
                 field_type = record._fields[field_name].type
                 if field_type == 'monetary':
                     # Compare monetary field.
-                    currency_field_name = record._fields[field_name]._related_currency_field
+                    currency_field_name = record._fields[field_name].currency_field
                     record_currency = record[currency_field_name]
                     if record_currency.compare_amounts(candidate_value, record_value)\
                             if record_currency else candidate_value != record_value: