Raise exception when attempting to dynamically route to a method that is already routed to. Fixes #940

1 files changed, 14 insertions, 0 deletions

diff --git a/rest_framework/routers.py b/rest_framework/routers.py
index c222f504..930011d3 100644
--- a/rest_framework/routers.py
+++ b/rest_framework/routers.py
@@ -15,7 +15,9 @@ For example, you might have a `urls.py` that looks something like this:
 """
 from __future__ import unicode_literals
 
+import itertools
 from collections import namedtuple
+from django.core.exceptions import ImproperlyConfigured
 from rest_framework import views
 from rest_framework.compat import patterns, url
 from rest_framework.response import Response
@@ -38,6 +40,13 @@ def replace_methodname(format_string, methodname):
     return ret
 
 
+def flatten(list_of_lists):
+    """
+    Takes an iterable of iterables, returns a single iterable containing all items
+    """
+    return itertools.chain(*list_of_lists)
+
+
 class BaseRouter(object):
     def __init__(self):
         self.registry = []
@@ -130,12 +139,17 @@ class SimpleRouter(BaseRouter):
         Returns a list of the Route namedtuple.
         """
 
+        known_actions = flatten([route.mapping.values() for route in self.routes])
+
         # Determine any `@action` or `@link` decorated methods on the viewset
         dynamic_routes = []
         for methodname in dir(viewset):
             attr = getattr(viewset, methodname)
             httpmethods = getattr(attr, 'bind_to_methods', None)
             if httpmethods:
+                if methodname in known_actions:
+                    raise ImproperlyConfigured('Cannot use @action or @link decorator on '
+                                               'method "%s" as it is an existing route' % methodname)
                 httpmethods = [method.lower() for method in httpmethods]
                 dynamic_routes.append((httpmethods, methodname))