[#3196] Fall back to app_globals on Flask g

If a property is not found on `g`, check CKAN's own `app_globals`,
where stuff like `g.site_title` is kept.

The default behaviour for Flask's `g` is to raise an AttributeError if
a missing property is accessed. We have kept this behaviour here and
handled a couple of cases where `c` was accessed outside of a request.
This can be reverted to returning an empty string if necessary.

ckan/authz.py

@@ -118,6 +118,9 @@ def _get_user(username):
     try:
         if c.userobj and c.userobj.name == username:
             return c.userobj
+    except AttributeError:
+        # c.userobj not set
+        pass
     except TypeError:
         # c is not available
         pass

ckan/config/middleware/flask_app.py

@@ -15,6 +15,7 @@ def make_flask_stack(conf, **app_conf):
     Pylons used """
 
     app = flask_app = CKANFlask(__name__)
+    app.app_ctx_globals_class = CKAN_AppCtxGlobals
 
     # Update Flask config with the CKAN values. We use the common config
     # object as values might have been modified on `load_environment`
@@ -38,6 +39,19 @@ def hello_world_post():
     return app
 
 
+class CKAN_AppCtxGlobals(_AppCtxGlobals):
+
+    '''Custom Flask AppCtxGlobal class (flask.g).'''
+
+    def __getattr__(self, name):
+        '''
+        If flask.g doesn't have attribute `name`, fall back to CKAN's
+        app_globals object.
+        If the key is also not found in there, an AttributeError will be raised
+        '''
+        return getattr(app_globals.app_globals, name)
+
+
 class CKANFlask(Flask):
 
     '''Extend the Flask class with a special method called on incoming

ckan/logic/__init__.py

@@ -220,6 +220,9 @@ def _prepopulate_context(context):
     context.setdefault('session', model.Session)
     try:
         context.setdefault('user', c.user)
+    except AttributeError:
+        # c.user not set
+        pass
     except TypeError:
         # c not registered
         pass