Added class based views

flask/views.py

@@ -0,0 +1,102 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.views
+    ~~~~~~~~~~~
+
+    This module provides class based views inspired by the ones in Django.
+
+    :copyright: (c) 2011 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+from .globals import request
+
+
+http_method_funcs = frozenset(['get', 'post', 'head', 'options',
+                               'delete', 'put', 'trace'])
+
+
+
+class View(object):
+    """Alternative way to use view functions.  A subclass has to implement
+    :meth:`dispatch_request` which is called with the view arguments from
+    the URL routing system.  If :attr:`methods` is provided the methods
+    do not have to be passed to the :meth:`~flask.Flask.add_url_rule`
+    method explicitly::
+
+        class MyView(View):
+            methods = ['GET']
+
+            def dispatch_request(self, name):
+                return 'Hello %s!' % name
+
+        app.add_url_rule('/hello/<name>', view_func=MyView.as_view('myview'))
+    """
+
+    methods = None
+
+    def dispatch_request(self):
+        raise NotImplementedError()
+
+    @classmethod
+    def as_view(cls, name, *class_args, **class_kwargs):
+        """Converts the class into an actual view function that can be
+        used with the routing system.  What it does internally is generating
+        a function on the fly that will instanciate the :class:`View`
+        on each request and call the :meth:`dispatch_request` method on it.
+
+        The arguments passed to :meth:`as_view` are forwarded to the
+        constructor of the class.
+        """
+        def view(*args, **kwargs):
+            self = cls(*class_args, **class_kwargs)
+            return self.dispatch_request(*args, **kwargs)
+        view.__name__ = name
+        view.__doc__ = cls.__doc__
+        view.__module__ = cls.__module__
+        view.methods = cls.methods
+        return view
+
+
+class MethodViewType(type):
+
+    def __new__(cls, name, bases, d):
+        rv = type.__new__(cls, name, bases, d)
+        if rv.methods is None:
+            methods = []
+            for key, value in d.iteritems():
+                if key in http_method_funcs:
+                    methods.append(key.upper())
+            # if we have no method at all in there we don't want to
+            # add a method list.  (This is for instance the case for
+            # the baseclass or another subclass of a base method view
+            # that does not introduce new methods).
+            if methods:
+                rv.methods = methods
+        return rv
+
+
+class MethodView(View):
+    """Like a regular class based view but that dispatches requests to
+    particular methods.  For instance if you implement a method called
+    :meth:`get` it means you will response to ``'GET'`` requests and
+    the :meth:`dispatch_request` implementation will automatically
+    forward your request to that.  Also :attr:`options` is set for you
+    automatically::
+
+        class CounterAPI(MethodView):
+
+            def get(self):
+                return session.get('counter', 0)
+
+            def post(self):
+                session['counter'] = session.get('counter', 0) + 1
+                return 'OK'
+
+        app.add_url_rule('/counter', view_func=CounterAPI.as_view('counter'))
+    """
+    __metaclass__ = MethodViewType
+
+    def dispatch_request(self, *args, **kwargs):
+        meth = getattr(self, request.method.lower(), None)
+        assert meth is not None, 'Not implemented method'
+        return meth(*args, **kwargs)