Config is now available in templates, context processors no longer override keys

CHANGES

@@ -17,6 +17,10 @@ Release date to be announced, codename to be decided.
   for the module.  This was implemented to aid GAE which will
   remove the static folder if it's part of a mapping in the .yml
   file.
+- the :attr:`~flask.Flask.config` is now available in the templates
+  as `config`.
+- context processors will no longer override values passed directly
+  to the render function.
 
 Version 0.5.1
 -------------

docs/upgrading.rst

@@ -30,6 +30,14 @@ how other systems handle request pre- and postprocessing.  If you
 dependend on the order of execution of post-request functions, be sure to
 change the order.
 
+Another change that breaks backwards compatibility is that context
+processors will no longer override values passed directly to the template
+rendering function.  If for example `request` is as variable passed
+directly to the template, the default context processor will not override
+it with the current request object.  This makes it easier to extend
+context processors later to inject additional variables without breaking
+existing template not expecting them.
+
 Version 0.5
 -----------
 

flask/app.py

@@ -343,7 +343,11 @@ class Flask(_PackageBoundObject):
 
     def update_template_context(self, context):
         """Update the template context with some commonly used variables.
-        This injects request, session and g into the template context.
+        This injects request, session, config and g into the template
+        context as well as everything template context processors want
+        to inject.  Note that the as of Flask 0.6, the original values
+        in the context will not be overriden if a context processor
+        decides to return a value with the same key.
 
         :param context: the context as a dictionary that is updated in place
                         to add extra variables.
@@ -352,8 +356,13 @@ class Flask(_PackageBoundObject):
         mod = _request_ctx_stack.top.request.module
         if mod is not None and mod in self.template_context_processors:
             funcs = chain(funcs, self.template_context_processors[mod])
+        orig_ctx = context.copy()
         for func in funcs:
             context.update(func())
+        # make sure the original values win.  This makes it possible to
+        # easier add new variables in context processors without breaking
+        # existing views.
+        context.update(orig_ctx)
 
     def run(self, host='127.0.0.1', port=5000, **options):
         """Runs the application on a local development server.  If the

flask/templating.py

@@ -19,6 +19,7 @@ def _default_template_ctx_processor():
     """
     reqctx = _request_ctx_stack.top
     return dict(
+        config=reqctx.app.config,
         request=reqctx.request,
         session=reqctx.session,
         g=reqctx.g

tests/flask_tests.py

@@ -492,6 +492,30 @@ class TemplatingTestCase(unittest.TestCase):
         rv = app.test_client().get('/')
         assert rv.data == '<p>23|42'
 
+    def test_original_win(self):
+        app = flask.Flask(__name__)
+        @app.route('/')
+        def index():
+            return flask.render_template_string('{{ config }}', config=42)
+        rv = app.test_client().get('/')
+        assert rv.data == '42'
+
+    def test_standard_context(self):
+        app = flask.Flask(__name__)
+        app.secret_key = 'development key'
+        @app.route('/')
+        def index():
+            flask.g.foo = 23
+            flask.session['test'] = 'aha'
+            return flask.render_template_string('''
+                {{ request.args.foo }}
+                {{ g.foo }}
+                {{ config.DEBUG }}
+                {{ session.test }}
+            ''')
+        rv = app.test_client().get('/?foo=42')
+        assert rv.data.split() == ['42', '23', 'False', 'aha']
+
     def test_escaping(self):
         text = '<p>Hello World!'
         app = flask.Flask(__name__)