Documented instance root

flask/app.py

@@ -554,6 +554,17 @@ class Flask(_PackageBoundObject):
         basedir = os.path.normpath(os.path.abspath(instance_path))
         return os.path.join(basedir, 'instance')
 
+    def open_instance_resource(self, resource, mode='rb'):
+        """Opens a resource from the application's instance folder
+        (:attr:`instance_path`).  Otherwise works like
+        :meth:`open_resource`.  Instance resources can also be opened for
+        writing.
+
+        :param resource: the name of the resource.  To access resources within
+                         subfolders use forward slashes as separator.
+        """
+        return open(os.path.join(self.instance_path, resource), mode)
+
     def create_jinja_environment(self):
         """Creates the Jinja2 environment based on :attr:`jinja_options`
         and :meth:`select_jinja_autoescape`.  Since 0.7 this also adds

flask/helpers.py

@@ -565,7 +565,7 @@ class _PackageBoundObject(object):
             raise RuntimeError('No static folder for this object')
         return send_from_directory(self.static_folder, filename)
 
-    def open_resource(self, resource):
+    def open_resource(self, resource, mode='rb'):
         """Opens a resource from the application's resource folder.  To see
         how this works, consider the following folder structure::
 
@@ -587,4 +587,6 @@ class _PackageBoundObject(object):
         :param resource: the name of the resource.  To access resources within
                          subfolders use forward slashes as separator.
         """
-        return open(os.path.join(self.root_path, resource), 'rb')
+        if mode not in ('r', 'rb'):
+            raise ValueError('Resources can only be opened for reading')
+        return open(os.path.join(self.root_path, resource), mode)