diff options
| -rw-r--r-- | rest_framework/pagination.py | 113 | ||||
| -rw-r--r-- | tests/test_pagination.py | 2 |
2 files changed, 68 insertions, 47 deletions
diff --git a/rest_framework/pagination.py b/rest_framework/pagination.py index cf1f1afa..58223f49 100644 --- a/rest_framework/pagination.py +++ b/rest_framework/pagination.py @@ -20,12 +20,12 @@ from rest_framework.utils.urls import ( ) -def _strict_positive_int(integer_string, cutoff=None): +def _positive_int(integer_string, strict=False, cutoff=None): """ Cast a string to a strictly positive integer. """ ret = int(integer_string) - if ret <= 0: + if ret < 0 or (ret == 0 and strict): raise ValueError() if cutoff: ret = min(ret, cutoff) @@ -126,6 +126,47 @@ def _get_page_links(page_numbers, current, url_func): return page_links +def _decode_cursor(encoded): + """ + Given a string representing an encoded cursor, return a `Cursor` instance. + """ + try: + querystring = b64decode(encoded.encode('ascii')).decode('ascii') + tokens = urlparse.parse_qs(querystring, keep_blank_values=True) + offset = _positive_int(tokens['offset'][0]) + reverse = bool(int(tokens['reverse'][0])) + position = tokens.get('position', [None])[0] + except (TypeError, ValueError): + return None + + return Cursor(offset=offset, reverse=reverse, position=position) + + +def _encode_cursor(cursor): + """ + Given a Cursor instance, return an encoded string representation. + """ + tokens = { + 'offset': str(cursor.offset), + 'reverse': '1' if cursor.reverse else '0', + } + if cursor.position is not None: + tokens['position'] = cursor.position + + querystring = urlparse.urlencode(tokens, doseq=True) + return b64encode(querystring.encode('ascii')).decode('ascii') + + +def _reverse_ordering(ordering_tuple): + """ + Given an order_by tuple such as `('-created', 'uuid')` reverse the + ordering and return a new tuple, eg. `('created', '-uuid')`. + """ + invert = lambda x: x[1:] if (x.startswith('-')) else '-' + x + return tuple([invert(item) for item in ordering_tuple]) + + +Cursor = namedtuple('Cursor', ['offset', 'reverse', 'position']) PageLink = namedtuple('PageLink', ['url', 'number', 'is_active', 'is_break']) PAGE_BREAK = PageLink(url=None, number=None, is_active=False, is_break=True) @@ -228,8 +269,9 @@ class PageNumberPagination(BasePagination): def get_page_size(self, request): if self.paginate_by_param: try: - return _strict_positive_int( + return _positive_int( request.query_params[self.paginate_by_param], + strict=True, cutoff=self.max_paginate_by ) except (KeyError, ValueError): @@ -312,7 +354,7 @@ class LimitOffsetPagination(BasePagination): def get_limit(self, request): if self.limit_query_param: try: - return _strict_positive_int( + return _positive_int( request.query_params[self.limit_query_param], cutoff=self.max_limit ) @@ -323,7 +365,7 @@ class LimitOffsetPagination(BasePagination): def get_offset(self, request): try: - return _strict_positive_int( + return _positive_int( request.query_params[self.offset_query_param], ) except (KeyError, ValueError): @@ -384,36 +426,10 @@ class LimitOffsetPagination(BasePagination): return template.render(context) -Cursor = namedtuple('Cursor', ['offset', 'reverse', 'position']) - - -def decode_cursor(encoded): - try: - querystring = b64decode(encoded.encode('ascii')).decode('ascii') - tokens = urlparse.parse_qs(querystring, keep_blank_values=True) - offset = int(tokens['offset'][0]) - reverse = bool(int(tokens['reverse'][0])) - position = tokens['position'][0] - except (TypeError, ValueError): - return None - - return Cursor(offset=offset, reverse=reverse, position=position) - - -def encode_cursor(cursor): - tokens = { - 'offset': str(cursor.offset), - 'reverse': '1' if cursor.reverse else '0', - 'position': cursor.position - } - querystring = urlparse.urlencode(tokens, doseq=True) - return b64encode(querystring.encode('ascii')).decode('ascii') - - class CursorPagination(BasePagination): - # TODO: handle queries with '' as a legitimate position # Support case where ordering is already negative # Support tuple orderings + # Determine how/if True, False and None positions work cursor_query_param = 'cursor' page_size = api_settings.PAGINATE_BY invalid_cursor_message = _('Invalid cursor') @@ -426,25 +442,26 @@ class CursorPagination(BasePagination): encoded = request.query_params.get(self.cursor_query_param) if encoded is None: self.cursor = None - (offset, reverse, current_position) = (0, False, '') + (offset, reverse, current_position) = (0, False, None) else: - self.cursor = decode_cursor(encoded) + self.cursor = _decode_cursor(encoded) if self.cursor is None: raise NotFound(self.invalid_cursor_message) (offset, reverse, current_position) = self.cursor # Cursor pagination always enforces an ordering. if reverse: - queryset = queryset.order_by('-' + self.ordering) + queryset = queryset.order_by(_reverse_ordering(self.ordering)) else: queryset = queryset.order_by(self.ordering) # If we have a cursor with a fixed position then filter by that. - if current_position != '': + if current_position is not None: + primary_ordering_attr = self.ordering[0].lstrip('-') if self.cursor.reverse: - kwargs = {self.ordering + '__lt': current_position} + kwargs = {primary_ordering_attr + '__lt': current_position} else: - kwargs = {self.ordering + '__gt': current_position} + kwargs = {primary_ordering_attr + '__gt': current_position} queryset = queryset.filter(**kwargs) # If we have an offset cursor then offset the entire page by that amount. @@ -468,7 +485,7 @@ class CursorPagination(BasePagination): if reverse: # Determine next and previous positions for reverse cursors. - self.has_next = current_position != '' or offset > 0 + self.has_next = (current_position is not None) or (offset > 0) self.has_previous = has_following_postion if self.has_next: self.next_position = current_position @@ -477,7 +494,7 @@ class CursorPagination(BasePagination): else: # Determine next and previous positions for forward cursors. self.has_next = has_following_postion - self.has_previous = current_position != '' or offset > 0 + self.has_previous = (current_position is not None) or (offset > 0) if self.has_next: self.next_position = following_position if self.has_previous: @@ -518,7 +535,7 @@ class CursorPagination(BasePagination): # Our cursor will have an offset equal to the page size, # but no position to filter against yet. offset = self.page_size - position = '' + position = None elif self.cursor.reverse: # The change in direction will introduce a paging artifact, # where we end up skipping forward a few extra items. @@ -531,7 +548,7 @@ class CursorPagination(BasePagination): position = self.previous_position cursor = Cursor(offset=offset, reverse=False, position=position) - encoded = encode_cursor(cursor) + encoded = _encode_cursor(cursor) return replace_query_param(self.base_url, self.cursor_query_param, encoded) def get_previous_link(self): @@ -567,7 +584,7 @@ class CursorPagination(BasePagination): # Our cursor will have an offset equal to the page size, # but no position to filter against yet. offset = self.page_size - position = '' + position = None elif self.cursor.reverse: # Use the position from the existing cursor and increment # it's offset by the page size. @@ -580,11 +597,15 @@ class CursorPagination(BasePagination): position = self.next_position cursor = Cursor(offset=offset, reverse=True, position=position) - encoded = encode_cursor(cursor) + encoded = _encode_cursor(cursor) return replace_query_param(self.base_url, self.cursor_query_param, encoded) def get_ordering(self): - return 'created' + """ + Return a tuple of strings, that may be used in an `order_by` method. + """ + return ('created',) def _get_position_from_instance(self, instance, ordering): - return str(getattr(instance, ordering)) + attr = getattr(instance, ordering[0]) + return six.text_type(attr) diff --git a/tests/test_pagination.py b/tests/test_pagination.py index e32dd028..fffdcbe9 100644 --- a/tests/test_pagination.py +++ b/tests/test_pagination.py @@ -450,7 +450,7 @@ class TestCursorPagination: ]) def order_by(self, ordering): - if ordering.startswith('-'): + if ordering[0].startswith('-'): return MockQuerySet(list(reversed(self.items))) return self |