From c0a170532e545d319df2f8ae4df360fd3db213dc Mon Sep 17 00:00:00 2001
From: Tero Vuotila <tero.vuotila@gmail.com>
Date: Thu, 25 Oct 2018 21:43:38 +0300
Subject: [PATCH] Store forced locale per request

Allow multiple request to share the same application.
---
 flask_babel/__init__.py | 15 ++++++++-------
 tests/tests.py          | 23 +++++++++++++++++++++++
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/flask_babel/__init__.py b/flask_babel/__init__.py
index bddb77b..58ebcee 100644
--- a/flask_babel/__init__.py
+++ b/flask_babel/__init__.py
@@ -251,10 +251,13 @@ def get_locale():
     locale = getattr(ctx, 'babel_locale', None)
     if locale is None:
         babel = current_app.extensions['babel']
-        if babel.locale_selector_func is None:
+        locale_selector_func = getattr(ctx, 'locale_selector_func', None)
+        if locale_selector_func is None:
+            locale_selector_func = babel.locale_selector_func
+        if locale_selector_func is None:
             locale = babel.default_locale
         else:
-            rv = babel.locale_selector_func()
+            rv = locale_selector_func()
             if rv is None:
                 locale = babel.default_locale
             else:
@@ -325,20 +328,18 @@ def force_locale(locale):
         yield
         return
 
-    babel = current_app.extensions['babel']
-
-    orig_locale_selector_func = babel.locale_selector_func
+    orig_locale_selector_func = getattr(ctx, 'locale_selector_func', None)
     orig_attrs = {}
     for key in ('babel_translations', 'babel_locale'):
         orig_attrs[key] = getattr(ctx, key, None)
 
     try:
-        babel.locale_selector_func = lambda: locale
+        ctx.locale_selector_func = lambda: locale
         for key in orig_attrs:
             setattr(ctx, key, None)
         yield
     finally:
-        babel.locale_selector_func = orig_locale_selector_func
+        ctx.locale_selector_func = orig_locale_selector_func
         for key, value in orig_attrs.items():
             setattr(ctx, key, value)
 
diff --git a/tests/tests.py b/tests/tests.py
index a987f05..2008ea3 100644
--- a/tests/tests.py
+++ b/tests/tests.py
@@ -204,6 +204,29 @@ def select_locale():
                 assert str(babel.get_locale()) == 'en_US'
             assert str(babel.get_locale()) == 'de_DE'
 
+    def test_force_locale_with_two_concurrent_requests(self):
+        app = flask.Flask(__name__)
+        b = babel.Babel(app)
+
+        @b.localeselector
+        def select_locale():
+            return 'de_DE'
+
+        def make_request(forced_locale):
+            with app.test_request_context():
+                assert str(babel.get_locale()) == 'de_DE'
+                with babel.force_locale(forced_locale):
+                    yield
+
+        request1 = make_request('en_US')
+        next(request1)
+
+        request2 = make_request('en_US')
+        next(request2)
+
+        next(request2, None)
+        next(request1, None)
+
 
 class NumberFormattingTestCase(unittest.TestCase):