Merge pull request #45 from cloudblue/opt/LITE-22313

LITE-22313 Optimized RQLLimitOffsetPagination to use only possible limit

Author: maxipavlovic

dj_rql/drf/paginations.py

@@ -42,12 +42,28 @@ def paginate_queryset(self, queryset, request, view=None):
                     'error': 'Limit and offset are set incorrectly.',
                 })
 
-        if self.get_limit() == 0:
+        self.limit = self.get_limit(request)
+        if self.limit == 0:
             self.count = self.get_count(queryset)
             self.offset = 0
             return []
 
-        return super(RQLLimitOffsetPagination, self).paginate_queryset(queryset, request, view)
+        elif self.limit is None:
+            return None
+
+        self.count = self.get_count(queryset)
+        self.offset = self.get_offset(request)
+        self.request = request
+        if self.count > self.limit and self.template is not None:
+            self.display_page_controls = True
+
+        if self.count == 0 or self.offset > self.count:
+            return []
+
+        if self.limit + self.offset > self.count:
+            self.limit = self.count - self.offset
+
+        return list(queryset[self.offset:self.offset + self.limit])
 
     def get_limit(self, *args):
         if self._rql_limit is not None:

tests/test_drf/test_pagination.py

@@ -205,6 +205,18 @@ def test_max_limit(self):
         queryset = self.paginate_queryset(request)
         assert queryset == list(range(51, 66))
 
+    def test_limit_gt_than_count_wout_offset(self):
+        self.pagination.max_limit = 500
+
+        request = Request(factory.get('/', {'limit': 125}))
+        queryset = self.paginate_queryset(request)
+        assert queryset == list(range(1, 101))
+
+    def test_limit_gt_than_count_with_offset(self):
+        request = Request(factory.get('/', {'limit': 125, 'offset': 95}))
+        queryset = self.paginate_queryset(request)
+        assert queryset == list(range(96, 101))
+
     def test_rql_operators(self):
         limit, offset = 1, 2
         request = Request(