Fix #12442: Add ability to request any translation of a string (#12443)

docs/l10n.rst

@@ -183,6 +183,13 @@ You could use that in a template like this:
 For our purposes these are mostly useful for things that can change, but which shouldn't involve
 retranslation of a string (e.g. URLs or email addresses).
 
+You may also request any other translation of the string (or the original English string of course) regardless of the current locale.
+
+.. code-block:: jinja
+
+    <h2>{{ ftl('welcome', locale='en', user='Dude') }}<h2>
+
+
 This helper is available in Jinja templates and Python code in views. For use in a view you should
 always call it in the view itself:
 

lib/l10n_utils/__init__.py

@@ -46,6 +46,8 @@ def render_to_string(template_name, context=None, request=None, using=None, ftl_
             context["fluent_l10n"] = fluent_l10n([locale, "en"], ftl_files)
         else:
             context["fluent_l10n"] = fluent_l10n([locale, "en"], settings.FLUENT_DEFAULT_FILES)
+
+        context["fluent_files"] = ftl_files or settings.FLUENT_DEFAULT_FILES
     return loader.render_to_string(template_name, context, request, using)
 
 
@@ -128,8 +130,7 @@ def render(request, template, context=None, ftl_files=None, activation_files=Non
     else:
         context["fluent_l10n"] = fluent_l10n([locale, "en"], settings.FLUENT_DEFAULT_FILES)
 
-    # Every template gets its own .lang file, so figure out what it is
-    # and pass it in the context
+    context["fluent_files"] = ftl_files or settings.FLUENT_DEFAULT_FILES
     context["template"] = template
     context["template_source_url"] = template_source_url(template)
 

lib/l10n_utils/fluent.py

@@ -145,7 +145,10 @@ def l10nize(f):
         # can not use += here because that mutates the original list
         ftl_files = ftl_files + settings.FLUENT_DEFAULT_FILES
         locale = kwargs.get("locale") or translation.get_language(True)
-        l10n = fluent_l10n([locale, "en"], ftl_files)
+        locales = [locale]
+        if locale != "en":
+            locales.append("en")
+        l10n = fluent_l10n(locales, ftl_files)
         return f(l10n, *args, **kwargs)
 
     return inner

lib/l10n_utils/templatetags/fluent.py

@@ -11,12 +11,13 @@ from lib.l10n_utils import fluent
 
 @library.global_function
 @jinja2.pass_context
-def ftl(ctx, message_id, fallback=None, **kwargs):
+def ftl(ctx, message_id, fallback=None, locale=None, **kwargs):
     """Return the translated string.
 
     :param ctx: the context from the template (automatically included)
     :param str message_id: the ID of the message
     :param str fallback: the ID of a message to use if message_id is not translated
+    :param str locale: If set the string returned will be from the given locale instead of the current one
     :param kwargs: the other kwargs are passed to the translation as variables
     :return: the translated string marked as safe
 
@@ -24,7 +25,11 @@ def ftl(ctx, message_id, fallback=None, **kwargs):
 
         <p>{{ ftl('greeting', name='The Dude') }}
     """
-    return Markup(fluent.translate(ctx["fluent_l10n"], message_id, fallback, **kwargs))
+    if locale:
+        return Markup(fluent.ftl(message_id, fallback, locale=locale, ftl_files=ctx["fluent_files"], **kwargs))
+
+    l10n = ctx["fluent_l10n"]
+    return Markup(fluent.translate(l10n, message_id, fallback, **kwargs))
 
 
 @library.global_function

lib/l10n_utils/tests/test_files/templates/test-en-title.html

@@ -0,0 +1,7 @@
+{#
+ This Source Code Form is subject to the terms of the Mozilla Public
+ License, v. 2.0. If a copy of the MPL was not distributed with this
+ file, You can obtain one at https://mozilla.org/MPL/2.0/.
+#}
+
+{{ ftl("fluent-title") }}:{{ ftl("fluent-title", locale="en") }}

lib/l10n_utils/tests/test_files/templates/test-fr-title.html

@@ -0,0 +1,7 @@
+{#
+ This Source Code Form is subject to the terms of the Mozilla Public
+ License, v. 2.0. If a copy of the MPL was not distributed with this
+ file, You can obtain one at https://mozilla.org/MPL/2.0/.
+#}
+
+{{ ftl("fluent-title") }}:{{ ftl("fluent-title", locale="fr") }}

lib/l10n_utils/tests/test_fluent.py

@@ -131,6 +131,8 @@ class TestFluentViewTranslationUtils(TestCase):
 
     def test_ftl_view_util(self):
         assert fluent.ftl("fluent-title", locale="de", ftl_files="mozorg/fluent") == "Title in German"
+        assert fluent.ftl("fluent-title", locale="fr", ftl_files="mozorg/fluent") == "Title in French"
+        assert fluent.ftl("fluent-title", locale="en", ftl_files="mozorg/fluent") == "This is a test of the new Fluent L10n system"
 
     def test_ftl_view_util_no_mutate_list(self):
         """Should not mutate the ftl_files list"""

lib/l10n_utils/tests/test_template.py

@@ -6,16 +6,17 @@ from pathlib import Path
 from unittest.mock import ANY, patch
 
 from django.template import TemplateDoesNotExist
-from django.test import RequestFactory
+from django.test import RequestFactory, override_settings
 
 from django_jinja.backend import Jinja2
 
 from bedrock.mozorg.tests import TestCase
-from lib.l10n_utils import render
+from lib.l10n_utils import render, render_to_string
 
 ROOT_PATH = Path(__file__).with_name("test_files")
 ROOT = str(ROOT_PATH)
 TEMPLATE_DIRS = [str(ROOT_PATH.joinpath("templates"))]
+L10N_PATH = ROOT_PATH.joinpath("l10n")
 jinja_env = Jinja2.get_default().env
 
 
@@ -27,6 +28,25 @@ class TestNoLocale(TestCase):
         render(request, "500.html")
 
 
+@override_settings(FLUENT_PATHS=[L10N_PATH])
+@patch.object(jinja_env.loader, "searchpath", TEMPLATE_DIRS)
+class TestFtlTemplateHelper(TestCase):
+    def setUp(self):
+        self.rf = RequestFactory()
+
+    def test_english_locale(self):
+        req = self.rf.get("/en-US/")
+        req.locale = "de"
+        result = render_to_string("test-en-title.html", request=req, ftl_files="mozorg/fluent")
+        assert result.strip() == "Title in German:This is a test of the new Fluent L10n system"
+
+    def test_french_locale(self):
+        req = self.rf.get("/en-US/")
+        req.locale = "en-US"
+        result = render_to_string("test-fr-title.html", request=req, ftl_files="mozorg/fluent")
+        assert result.strip() == "This is a test of the new Fluent L10n system:Title in French"
+
+
 @patch.object(jinja_env.loader, "searchpath", TEMPLATE_DIRS)
 @patch("lib.l10n_utils.django_render")
 class TestLocaleTemplates(TestCase):