Fixed admin pagination when limit is 0.

Author: mitar

rest_framework/pagination.py

@@ -313,13 +313,22 @@ def get_paginated_response(self, data):
             ('results', data)
         ]))
 
+    def get_zero_limit(self):
+        # By default we return max_limit, but one could also return default_limit.
+        return self.max_limit
+
     def get_limit(self, request):
         if self.limit_query_param:
             try:
-                return _positive_int(
+                limit = _positive_int(
                     request.query_params[self.limit_query_param],
                     cutoff=self.max_limit
                 )
+                # User can specify limit == 0 to specify max (and not default) limit.
+                # By default (max_limit is None) this disables pagination.
+                if limit == 0:
+                    limit = self.get_zero_limit()
+                return limit
             except (KeyError, ValueError):
                 pass
 
@@ -357,7 +366,23 @@ def get_previous_link(self):
         return replace_query_param(url, self.offset_query_param, offset)
 
     def get_html_context(self):
+        # paginate_queryset should be called before, to set
+        # self.limit and other values on self.
+
+        if self.limit is None:
+            return {
+                'previous_url': None,
+                'next_url': None,
+                'page_links': []
+            }
+
         base_url = self.request.build_absolute_uri()
+
+        # This changes the URL in fact only when limit is 0 (which makes limit == max_limit)
+        # or when limit is missing (which makes it default_limit). We want to inform
+        # the user what this effective limit is.
+        base_url = replace_query_param(base_url, self.limit_query_param, self.limit)
+
         current = _divide_with_ceil(self.offset, self.limit) + 1
         # The number of pages is a little bit fiddly.
         # We need to sum both the number of pages from current offset to end

tests/test_pagination.py

@@ -322,7 +322,10 @@ class ExamplePagination(pagination.LimitOffsetPagination):
         self.queryset = range(1, 101)
 
     def paginate_queryset(self, request):
-        return list(self.pagination.paginate_queryset(self.queryset, request))
+        queryset = self.pagination.paginate_queryset(self.queryset, request)
+        if queryset is None:
+            return None
+        return list(queryset)
 
     def get_paginated_content(self, queryset):
         response = self.pagination.get_paginated_response(queryset)
@@ -505,6 +508,52 @@ def test_max_limit(self):
         assert content.get('next') == next_url
         assert content.get('previous') == prev_url
 
+    def test_limit_is_zero(self):
+        """
+        A limit of zero should set limit to max_limit.
+        """
+        offset = 20
+        request = Request(factory.get('/', {'limit': 0, 'offset': offset}))
+        queryset = self.paginate_queryset(request)
+        content = self.get_paginated_content(queryset)
+        context = self.get_html_context()
+        assert queryset == self.queryset[20:35]
+        assert content == {
+            'results': self.queryset[20:35],
+            'previous': 'http://testserver/?limit=15&offset=5',
+            'next': 'http://testserver/?limit=15&offset=35',
+            'count': 100
+        }
+        assert context == {
+            'previous_url': 'http://testserver/?limit=15&offset=5',
+            'next_url': 'http://testserver/?limit=15&offset=35',
+            'page_links': [
+                PageLink('http://testserver/?limit=15', 1, False, False),
+                PageLink('http://testserver/?limit=15&offset=5', 2, False, False),
+                PageLink('http://testserver/?limit=15&offset=20', 3, True, False),
+                PageLink('http://testserver/?limit=15&offset=35', 4, False, False),
+                PAGE_BREAK,
+                PageLink('http://testserver/?limit=15&offset=95', 8, False, False),
+            ]
+        }
+
+    def test_limit_is_zero_with_no_limit(self):
+        """
+        A limit of zero should set limit to max_limit, but when it is None,
+        pagination should be disabled and whole queryset returned.
+        """
+        self.pagination.max_limit = None
+        offset = 30
+        request = Request(factory.get('/', {'limit': 0, 'offset': offset}))
+        queryset = self.paginate_queryset(request)
+        context = self.get_html_context()
+        assert queryset is None
+        assert context == {
+            'previous_url': None,
+            'next_url': None,
+            'page_links': []
+        }
+
 
 class TestCursorPagination:
     """