[#3196] Add Flask-babel requirement, hook into Flask middleware

ckan/config/middleware/flask_app.py

@@ -12,6 +12,7 @@
 from werkzeug.exceptions import HTTPException
 from werkzeug.routing import Rule
 
+from flask_babel import Babel
 from flask_debugtoolbar import DebugToolbarExtension
 
 from paste.deploy.converters import asbool
@@ -133,6 +134,24 @@ def c_object():
         '''
         return dict(c=g)
 
+    # Babel
+    app.config[u'BABEL_TRANSLATION_DIRECTORIES'] = os.path.join(root, u'i18n')
+    # TODO: this relies on unpublished changes in flask-babel
+    app.config[u'BABEL_DOMAIN'] = 'ckan'
+
+    babel = Babel(app)
+
+    @babel.localeselector
+    def get_locale():
+        u'''
+        Return the value of the `CKAN_LANG` key of the WSGI environ,
+        set by the I18nMiddleware based on the URL.
+        If no value is defined, it defaults to `ckan.locale_default` or `en`.
+        '''
+        return request.environ.get(
+            u'CKAN_LANG',
+            config.get(u'ckan.locale_default', u'en'))
+
     @app.route('/hello', methods=['GET'])
     def hello_world():
         return 'Hello World, this is served by Flask'

requirements.in

@@ -5,6 +5,7 @@ Beaker==1.8.0 # Needs to be pinned to a more up to date version than the Pylons
 bleach==1.4.3
 fanstatic==0.12
 Flask==0.10.1
+Flask-Babel==0.11.1
 Jinja2==2.8
 Markdown==2.6.6
 ofs==0.4.2

requirements.txt

@@ -11,6 +11,7 @@ bleach==1.4.3
 decorator==4.0.6          # via pylons, sqlalchemy-migrate
 fanstatic==0.12
 Flask==0.10.1
+Flask-Babel==0.11.1
 FormEncode==1.3.0
 html5lib==0.9999999       # via bleach
 itsdangerous==0.24        # via flask