Django: fixes pagination parameter

When a user pass the `p` parameter in query,
Django returns a string. The string needs to be
casted to integer in order to be used in the paginator.
Otherwise, the response returns BadRequest.

restless/dj.py

@@ -27,8 +27,10 @@ def serialize_list(self, data):
         if getattr(self, 'paginate', False):
             page_size = getattr(self, 'page_size', getattr(settings, 'RESTLESS_PAGE_SIZE', 10))
             paginator = Paginator(data, page_size)
-
-            page_number = self.request.GET.get('p', 1)
+            try:
+                page_number = int(self.request.GET.get('p', 1))
+            except ValueError:
+                raise BadRequest('Invalid page number')
 
             if page_number not in paginator.page_range:
                 raise BadRequest('Invalid page number')

tests/test_dj.py

@@ -279,6 +279,14 @@ def test_as_list_paginated_invalid_page(self):
         self.assertEqual(resp['Content-Type'], 'application/json')
         self.assertEqual(resp.status_code, 400)
 
+    def test_as_list_paginated_page_number_is_not_integer(self):
+        list_endpoint = DjTestResourcePaginated().as_list()
+        req = FakeHttpRequest('GET', get_request={'p': 'string'})
+
+        resp = list_endpoint(req)
+        self.assertEqual(resp['Content-Type'], 'application/json')
+        self.assertEqual(resp.status_code, 400)
+
     def test_as_detail(self):
         detail_endpoint = DjTestResource.as_detail()
         req = FakeHttpRequest('GET')