Add Long Lived User Tokens

docs/api.rst

@@ -330,6 +330,31 @@ Generates Facebook login URL to request access token and permissions.
     fb_login_url = graph.auth_url(app_id, canvas_url, perms)
     print(fb_login_url)
 
+get_code_from_token
+^^^^^^^^^^^^^^^^^^^
+https://developers.facebook.com/docs/facebook-login/access-tokens/expiration-and-extension/
+
+Exchanges an existing long livd user access token on the server side for a
+code that can be redeemed for a long lived user token on the client side.
+
+**Parameters**
+
+* ``app_id`` - ``integer`` Facebook application id that is requesting a code.
+* ``app_secret`` - ``string`` Facebook application secret that is attempting
+  to get a code from the access token.
+* ``redirect_uri`` - ``string`` Return URL after successful authentication,
+  usually parses returned Facebook response for authorisation request.
+
+**Example**
+
+.. code-block:: python
+
+    app_id = 1231241241
+    app_secret = '123abc456def'
+    redirect_uri = 'https://domain.com/that-handles-auth-response/'
+    code = graph.get_code_from_token(app_id, app_secret, redirect_uri)
+    print(code)
+
 get_permissions
 ^^^^^^^^^^^^^^^
 

facebook/__init__.py

@@ -311,6 +311,26 @@ def get_app_access_token(self, app_id, app_secret, offline=False):
             return self.request("{0}/oauth/access_token".format(self.version),
                                 args=args)["access_token"]
 
+    def get_code_from_token(self, app_id, app_secret, redirect_uri):
+        """
+        Gets a code to be exchanged for a long lived token.
+        Uses a pre-existing server side long lived token to return a code
+        that can be redeemed for a client side long lived token.
+        """
+        args = {'access_token': self.access_token,
+                'client_id': app_id,
+                'client_secret': app_secret,
+                'redirect_uri': redirect_uri}
+
+        try:
+            code = self.request("{0}/oauth/client_code".format(self.version),
+                                args=args)["code"]
+            return code
+        except GraphAPIError:
+            self.access_token = self.extend_access_token(app_id, app_secret)
+            code = self.request("{0}/oauth/client_code".format(self.version),
+                                args=args)["code"]
+
     def get_access_token_from_code(
             self, code, redirect_uri, app_id, app_secret):
         """Get an access token from the "code" returned from an OAuth dialog.

test/test_facebook.py

@@ -190,6 +190,25 @@ def test_extend_access_token(self):
             self.assertEqual(
                 e.message, "fb_exchange_token parameter not specified")
 
+    def test_get_code_from_token(self):
+        """
+        Test that get_code_from_token returns a valid code which can be
+        exchanged for an access token.
+        """
+        redirect_uri = 'https://localhost/facebook/callback/'
+        app_token = facebook.GraphAPI().get_app_access_token(self.app_id,
+                                                             self.secret)
+        self.create_test_users(self.app_id,
+                          facebook.GraphAPI(app_token), 1)
+        test_token = self.test_users[0]['access_token']
+        graph = facebook.GraphAPI(test_token)
+        self.assertIsNotNone(graph.get_code_from_token(
+                        self.app_id, self.secret, redirect_uri),
+                        'Code not returned by get_code_from_token method')
+        self.assertIsNotNone(graph.get_access_token_from_code(
+                        self.app_id, self.secret), 'Invalid code returned by'
+                        'get_code_from_token method')
+
     def test_bogus_access_token(self):
         graph = facebook.GraphAPI(access_token='wrong_token')
         self.assertRaises(facebook.GraphAPIError, graph.get_object, 'me')