[FIX] base: single lang behaviour

If a db is in single lang (en_US or not) but still has translations, the
translation should be updated in addition to updating the referenced record
Add tests to formalise the expected behaviour:

If one language only (en_US or not), when writing on a translatable field:
- record field should updated
- value of potential existing en_US translation should be updated
- src of potential existing translations should be updated
- no new translation should be created

If en_US and fr_FR, when writing on a translatable field in en_US:
- record field should updated
- value of potential existing en_US translation should be updated
- src of potential existing translations should be updated
- new en_US translation should be created if was not present

If en_US and fr_FR, when writing on a translatable field in fr_FR:
- record field should not be updated
- value of potential existing fr_FR translation should be updated
- src of potential existing translations should not be updated
- new fr_FR translation should be created if was not present

Adapt test_new_api test
get_installed is ormcached, just putting active = True is not enough

odoo/addons/base/models/ir_translation.py

@@ -649,6 +649,30 @@ class IrTranslation(models.Model):
             """.format(", ".join(["%s"] * len(rows_by_type['model_terms'])))
             self.env.cr.execute(query, rows_by_type['model_terms'])
 
+    def _update_translations(self, vals_list):
+        """ Update translations of type 'model' or 'model_terms'.
+
+            This method is used for update of translations where the given
+            ``vals_list`` is trusted to be the right values
+            No new translation will be created
+        """
+        grouped_rows = {}
+        for vals in vals_list:
+            key = (vals['lang'], vals['type'], vals['name'])
+            grouped_rows.setdefault(key, [vals['value'], vals['src'], vals['state'], []])
+            grouped_rows[key][3].append(vals['res_id'])
+
+        for where, values in grouped_rows.items():
+            self._cr.execute(
+                """ UPDATE ir_translation
+                    SET value=%s,
+                        src=%s,
+                        state=%s
+                    WHERE lang=%s AND type=%s AND name=%s AND res_id in %s
+                """,
+                (values[0], values[1], values[2], where[0], where[1], where[2], tuple(values[3]))
+            )
+
     @api.model
     def translate_fields(self, model, id, field=None):
         """ Open a view for translating the field(s) of the record (model, id). """

odoo/addons/base/tests/test_translate.py

@@ -393,6 +393,92 @@ class TestTranslation(TransactionCase):
         ])
         self.assertEqual(translation_fr.src, 'Customers', "Did not set English version as source")
 
+class TestTranslationWrite(TransactionCase):
+
+    def setUp(self):
+        super().setUp()
+        self.category = self.env['res.partner.category'].create({'name': 'Reblochon'})
+
+    def test_01_en(self):
+        langs = self.env['res.lang'].get_installed()
+        self.assertEqual([('en_US', 'English (US)')], langs, "Test did not started with expected languages")
+
+        self.category.with_context(lang='en_US').write({'name': 'English Name'})
+        name = self.category.with_context(lang=None).read(['name'])
+        self.assertEqual(name[0]['name'], "English Name", "Reference field not updated")
+        translations = self.env['ir.translation'].search([
+            ('name', '=', 'res.partner.category,name'),
+            ('res_id', '=', self.category.id),
+            ('lang', '=', 'en_US'),
+        ])
+        self.assertEqual(len(translations), 0, "No English translation should be created when writing in English")
+
+    def test_02_en_translated(self):
+        langs = self.env['res.lang'].get_installed()
+        self.assertEqual([('en_US', 'English (US)')], langs, "Test did not started with expected languages")
+        translation = self.env['ir.translation'].create({
+            'type': 'model',
+            'name': 'res.partner.category,name',
+            'lang': 'en_US',
+            'res_id': self.category.id,
+            'src': 'Reblochon',
+            'value': 'Translated Name',
+            'state': 'translated',
+        })
+
+        self.category.with_context(lang='en_US').write({'name': 'English Name'})
+        translation_value = translation.read(['value'])
+        self.assertEqual(translation_value[0]['value'], "English Name", "Existing translation was not updated")
+
+        source_name = self.category.with_context(lang=None).read(['name'])
+        self.assertEqual(source_name[0]['name'], "English Name", "Reference field not updated")
+
+    def test_03_fr_single(self):
+        self.env['res.lang'].load_lang('fr_FR')
+        self.env['res.users'].with_context(active_test=False).search([]).write({'lang': 'fr_FR'})
+        self.env.ref('base.lang_en').active = False
+
+        langs = self.env['res.lang'].get_installed()
+        self.assertEqual([('fr_FR', 'French / Français')], langs, "Test did not started with expected languages")
+
+        self.category.with_context(lang='fr_FR').write({'name': 'French Name'})
+        source_name = self.category.with_context(lang=None).read(['name'])
+        self.assertEqual(source_name[0]['name'], "French Name", "Reference field not updated")
+        translations = self.env['ir.translation'].search([
+            ('name', '=', 'res.partner.category,name'),
+            ('res_id', '=', self.category.id),
+            ('lang', '=', 'fr_FR'),
+        ])
+        self.assertEqual(len(translations), 0, "No French translation should be created when writing in French")
+
+    def test_04_fr_multi(self):
+        self.env['res.lang'].load_lang('fr_FR')
+
+        langs = self.env['res.lang'].get_installed()
+        self.assertEqual([('en_US', 'English (US)'), ('fr_FR', 'French / Français')], langs,
+            "Test did not started with expected languages")
+        self.env['ir.translation'].create({
+            'type': 'model',
+            'name': 'res.partner.category,name',
+            'lang': 'en_US',
+            'res_id': self.category.id,
+            'src': 'Reblochon',
+            'value': 'Translated Name',
+            'state': 'translated',
+        })
+
+        self.category.with_context(lang='fr_FR').write({'name': 'French Name'})
+        self.category.with_context(lang='en_US').write({'name': 'English Name'})
+        translations = self.env['ir.translation'].search([
+            ('name', '=', 'res.partner.category,name'),
+            ('res_id', '=', self.category.id),
+        ], order='lang')
+        self.assertRecordValues(translations, [
+            {'src': 'English Name', 'value': 'English Name', 'lang': 'en_US'},
+            {'src': 'English Name', 'value': 'French Name', 'lang': 'fr_FR'}
+        ])
+      
+
 
 class TestXMLTranslation(TransactionCase):
     def setUp(self):

odoo/addons/test_new_api/tests/test_new_fields.py

@@ -1230,8 +1230,7 @@ class TestFields(common.TransactionCase):
         email = self.env.ref('test_new_api.emailmessage_0_0')
         self.assertEqual(email.message, message)
 
-        french = self.env['res.lang']._lang_get('fr_FR')
-        french.active = True
+        self.env['res.lang'].load_lang('fr_FR')
 
         def count(msg):
             # return the number of translations of msg.label

odoo/models.py

@@ -3397,6 +3397,12 @@ Fields:
         other_fields = []               # list of non-column fields
         single_lang = len(self.env['res.lang'].get_installed()) <= 1
         has_translation = self.env.lang and self.env.lang != 'en_US'
+        # when there is only one language, update existing translations but
+        # do not create new ones
+        if single_lang:
+            process_translations = self.env['ir.translation']._update_translations
+        else:
+            process_translations = self.env['ir.translation']._upsert_translations
 
         for name, val in vals.items():
             field = self._fields[name]
@@ -3411,7 +3417,7 @@ Fields:
                     val = field.convert_to_column(val, self, vals)
                     columns.append((name, field.column_format, val))
                     tname = "%s,%s" % (self._name, name)
-                    if field.translate is True and not single_lang:
+                    if field.translate is True and self.env.lang:
                         self.env['ir.translation']._set_source(tname, self.ids, val)
                 updated.append(name)
             else:
@@ -3451,7 +3457,7 @@ Fields:
                     # synchronize translated terms when possible.
                     self.env['ir.translation']._sync_terms_translations(field, self)
 
-                elif has_translation and field.translate:
+                elif self.env.lang and field.translate:
                     # The translated value of a field has been modified.
                     src_trans = self.with_context(lang=None).read([name])[0][name]
                     if not src_trans:
@@ -3469,7 +3475,8 @@ Fields:
                         state='translated',
                         res_id=res_id) for res_id in self.ids]
 
-            self.env['ir.translation']._upsert_translations(translation_values)
+            if translation_values:
+                process_translations(translation_values)
 
         # mark fields to recompute; do this before setting other fields, because
         # the latter can require the value of computed fields, e.g., a one2many