feat: Adds a language option to the update_translation_fields commands

Refs #563
Co-authored-by Fernando Cordeiro <fernando.cordeiro@jeronimo-martins.com>

docs/modeltranslation/commands.rst

@@ -23,10 +23,14 @@ command:
     $ python manage.py update_translation_fields
 
 Taken the news example used throughout the documentation this command will copy
-the value from the news object's ``title`` field to the default translation
-field ``title_de``. It only does so if the default translation field is empty
+the value from the news object's ``title`` field to the translation
+field ``title_de``. It only does so if the translation field is empty
 otherwise nothing is copied.
 
+On default, only the *default language* will have its translation field populated,
+but you can provide a ``--language`` option to specify any other language listed
+in ``settings.py``.
+
 .. note::
 
     Unless you configured modeltranslation to

modeltranslation/management/commands/update_translation_fields.py

@@ -1,14 +1,17 @@
 # -*- coding: utf-8 -*-
 from django.db.models import F, Q
-from django.core.management.base import BaseCommand
+from django.core.management.base import BaseCommand, CommandError
 
-from modeltranslation.settings import DEFAULT_LANGUAGE
+from modeltranslation.settings import AVAILABLE_LANGUAGES, DEFAULT_LANGUAGE
 from modeltranslation.translator import translator
 from modeltranslation.utils import build_localized_fieldname
 
 
+COMMASPACE = ", "
+
+
 class Command(BaseCommand):
-    help = ('Updates empty values of default translation fields using'
+    help = ('Updates empty values of translation fields using'
             ' values from original fields (in all translated models).')
 
     def add_arguments(self, parser):
@@ -20,6 +23,12 @@ class Command(BaseCommand):
             'model_name', nargs='?',
             help='Model name to update empty values of only this model.',
         )
+        parser.add_argument(
+            '--language',
+            action='store',
+            help=('Language translation field the be updated.'
+                  ' Default language field if not provided')
+        )
 
     def handle(self, *args, **options):
         verbosity = options['verbosity']
@@ -41,6 +50,17 @@ class Command(BaseCommand):
             model_name = model_name.lower()
             models = [m for m in models if m._meta.model_name == model_name]
 
+        # optionally defining the translation field language
+        lang = options.get('language') or DEFAULT_LANGUAGE
+        if lang not in AVAILABLE_LANGUAGES:
+            raise CommandError(
+                "Cannot find language '%s'. Options are %s." % (
+                    lang, COMMASPACE.join(AVAILABLE_LANGUAGES)
+                )
+            )
+        else:
+            lang = lang.replace('-', '_')
+
         if verbosity > 0:
             self.stdout.write("Working on models: %s" % ', '.join([
                 "{app_label}.{object_name}".format(**m._meta.__dict__)
@@ -53,7 +73,7 @@ class Command(BaseCommand):
 
             opts = translator.get_options_for_model(model)
             for field_name in opts.fields.keys():
-                def_lang_fieldname = build_localized_fieldname(field_name, DEFAULT_LANGUAGE)
+                def_lang_fieldname = build_localized_fieldname(field_name, lang)
 
                 # We'll only update fields which do not have an existing value
                 q = Q(**{def_lang_fieldname: None})

modeltranslation/tests/tests.py

@@ -17,6 +17,7 @@ from django.core.exceptions import ValidationError, ImproperlyConfigured
 from django.core.files.base import ContentFile
 from django.core.files.storage import default_storage
 from django.core.management import call_command
+from django.core.management.base import CommandError
 from django.db import IntegrityError
 from django.db.models import Q, F, Count, TextField
 from django.test import TestCase, TransactionTestCase
@@ -2024,6 +2025,24 @@ class UpdateCommandTest(ModeltranslationTestBase):
         self.assertEqual('initial', obj1.title_de)
         self.assertEqual('already', obj2.title_de)
 
+    def test_update_command_language_param(self):
+        trans_real.activate('en')
+        pk1 = models.TestModel.objects.create(title_en='').pk
+        pk2 = models.TestModel.objects.create(title_en='already').pk
+        # Due to ``rewrite(False)`` here, original field will be affected.
+        models.TestModel.objects.all().rewrite(False).update(title='initial')
+
+        call_command('update_translation_fields', language='en', verbosity=0)
+
+        obj1 = models.TestModel.objects.get(pk=pk1)
+        obj2 = models.TestModel.objects.get(pk=pk2)
+        self.assertEqual('initial', obj1.title_en)
+        self.assertEqual('already', obj2.title_en)
+
+    def test_update_command_invalid_language_param(self):
+        with self.assertRaises(CommandError):
+            call_command('update_translation_fields', language='xx', verbosity=0)
+
 
 class TranslationAdminTest(ModeltranslationTestBase):
     def setUp(self):