diff options
Diffstat (limited to 'rest_framework/pagination.py')
| -rw-r--r-- | rest_framework/pagination.py | 221 |
1 files changed, 198 insertions, 23 deletions
diff --git a/rest_framework/pagination.py b/rest_framework/pagination.py index b9d48796..1b7524c6 100644 --- a/rest_framework/pagination.py +++ b/rest_framework/pagination.py @@ -3,14 +3,18 @@ Pagination serializers determine the structure of the output that should be used for paginated responses. """ from __future__ import unicode_literals +from collections import namedtuple from django.core.paginator import InvalidPage, Paginator as DjangoPaginator +from django.template import Context, loader from django.utils import six from django.utils.translation import ugettext as _ from rest_framework.compat import OrderedDict from rest_framework.exceptions import NotFound from rest_framework.response import Response from rest_framework.settings import api_settings -from rest_framework.templatetags.rest_framework import replace_query_param +from rest_framework.utils.urls import ( + replace_query_param, remove_query_param +) def _strict_positive_int(integer_string, cutoff=None): @@ -25,23 +29,117 @@ def _strict_positive_int(integer_string, cutoff=None): return ret +def _divide_with_ceil(a, b): + """ + Returns 'a' divded by 'b', with any remainder rounded up. + """ + if a % b: + return (a // b) + 1 + return a // b + + def _get_count(queryset): """ Determine an object count, supporting either querysets or regular lists. """ try: return queryset.count() - except AttributeError: + except (AttributeError, TypeError): return len(queryset) +def _get_displayed_page_numbers(current, final): + """ + This utility function determines a list of page numbers to display. + This gives us a nice contextually relevant set of page numbers. + + For example: + current=14, final=16 -> [1, None, 13, 14, 15, 16] + + This implementation gives one page to each side of the cursor, + or two pages to the side when the cursor is at the edge, then + ensures that any breaks between non-continous page numbers never + remove only a single page. + + For an alernativative implementation which gives two pages to each side of + the cursor, eg. as in GitHub issue list pagination, see: + + https://gist.github.com/tomchristie/321140cebb1c4a558b15 + """ + assert current >= 1 + assert final >= current + + if final <= 5: + return list(range(1, final + 1)) + + # We always include the first two pages, last two pages, and + # two pages either side of the current page. + included = set(( + 1, + current - 1, current, current + 1, + final + )) + + # If the break would only exclude a single page number then we + # may as well include the page number instead of the break. + if current <= 4: + included.add(2) + included.add(3) + if current >= final - 3: + included.add(final - 1) + included.add(final - 2) + + # Now sort the page numbers and drop anything outside the limits. + included = [ + idx for idx in sorted(list(included)) + if idx > 0 and idx <= final + ] + + # Finally insert any `...` breaks + if current > 4: + included.insert(1, None) + if current < final - 3: + included.insert(len(included) - 1, None) + return included + + +def _get_page_links(page_numbers, current, url_func): + """ + Given a list of page numbers and `None` page breaks, + return a list of `PageLink` objects. + """ + page_links = [] + for page_number in page_numbers: + if page_number is None: + page_link = PAGE_BREAK + else: + page_link = PageLink( + url=url_func(page_number), + number=page_number, + is_active=(page_number == current), + is_break=False + ) + page_links.append(page_link) + return page_links + + +PageLink = namedtuple('PageLink', ['url', 'number', 'is_active', 'is_break']) + +PAGE_BREAK = PageLink(url=None, number=None, is_active=False, is_break=True) + + class BasePagination(object): - def paginate_queryset(self, queryset, request, view): + display_page_controls = False + + def paginate_queryset(self, queryset, request, view=None): # pragma: no cover raise NotImplemented('paginate_queryset() must be implemented.') - def get_paginated_response(self, data): + def get_paginated_response(self, data): # pragma: no cover raise NotImplemented('get_paginated_response() must be implemented.') + def to_html(self): # pragma: no cover + raise NotImplemented('to_html() must be implemented to display page controls.') + class PageNumberPagination(BasePagination): """ @@ -66,10 +164,15 @@ class PageNumberPagination(BasePagination): # Only relevant if 'paginate_by_param' has also been set. max_paginate_by = api_settings.MAX_PAGINATE_BY - def paginate_queryset(self, queryset, request, view): + last_page_strings = ('last',) + + template = 'rest_framework/pagination/numbers.html' + + def _handle_backwards_compat(self, view): """ - Paginate a queryset if required, either returning a - page object, or `None` if pagination is not configured for this view. + Prior to version 3.1, pagination was handled in the view, and the + attributes were set there. The attributes should now be set on + the pagination class, but the old style is still pending deprecation. """ for attr in ( 'paginate_by', 'page_query_param', @@ -78,23 +181,21 @@ class PageNumberPagination(BasePagination): if hasattr(view, attr): setattr(self, attr, getattr(view, attr)) + def paginate_queryset(self, queryset, request, view=None): + """ + Paginate a queryset if required, either returning a + page object, or `None` if pagination is not configured for this view. + """ + self._handle_backwards_compat(view) + page_size = self.get_page_size(request) if not page_size: return None paginator = DjangoPaginator(queryset, page_size) - page_string = request.query_params.get(self.page_query_param, 1) - try: - page_number = paginator.validate_number(page_string) - except InvalidPage: - if page_string == 'last': - page_number = paginator.num_pages - else: - msg = _( - 'Choose a valid page number. Page numbers must be a ' - 'whole number, or must be the string "last".' - ) - raise NotFound(msg) + page_number = request.query_params.get(self.page_query_param, 1) + if page_number in self.last_page_strings: + page_number = paginator.num_pages try: self.page = paginator.page(page_number) @@ -104,6 +205,10 @@ class PageNumberPagination(BasePagination): ) raise NotFound(msg) + if paginator.count > 1: + # The browsable API should display pagination controls. + self.display_page_controls = True + self.request = request return self.page @@ -139,8 +244,35 @@ class PageNumberPagination(BasePagination): return None url = self.request.build_absolute_uri() page_number = self.page.previous_page_number() + if page_number == 1: + return remove_query_param(url, self.page_query_param) return replace_query_param(url, self.page_query_param, page_number) + def get_html_context(self): + base_url = self.request.build_absolute_uri() + + def page_number_to_url(page_number): + if page_number == 1: + return remove_query_param(base_url, self.page_query_param) + else: + return replace_query_param(base_url, self.page_query_param, page_number) + + current = self.page.number + final = self.page.paginator.num_pages + page_numbers = _get_displayed_page_numbers(current, final) + page_links = _get_page_links(page_numbers, current, page_number_to_url) + + return { + 'previous_url': self.get_previous_link(), + 'next_url': self.get_next_link(), + 'page_links': page_links + } + + def to_html(self): + template = loader.get_template(self.template) + context = Context(self.get_html_context()) + return template.render(context) + class LimitOffsetPagination(BasePagination): """ @@ -153,12 +285,15 @@ class LimitOffsetPagination(BasePagination): limit_query_param = 'limit' offset_query_param = 'offset' max_limit = None + template = 'rest_framework/pagination/numbers.html' - def paginate_queryset(self, queryset, request, view): + def paginate_queryset(self, queryset, request, view=None): self.limit = self.get_limit(request) self.offset = self.get_offset(request) self.count = _get_count(queryset) self.request = request + if self.count > self.limit: + self.display_page_controls = True return queryset[self.offset:self.offset + self.limit] def get_paginated_response(self, data): @@ -189,16 +324,56 @@ class LimitOffsetPagination(BasePagination): except (KeyError, ValueError): return 0 - def get_next_link(self, page): + def get_next_link(self): if self.offset + self.limit >= self.count: return None + url = self.request.build_absolute_uri() offset = self.offset + self.limit return replace_query_param(url, self.offset_query_param, offset) - def get_previous_link(self, page): - if self.offset - self.limit < 0: + def get_previous_link(self): + if self.offset <= 0: return None + url = self.request.build_absolute_uri() + + if self.offset - self.limit <= 0: + return remove_query_param(url, self.offset_query_param) + offset = self.offset - self.limit return replace_query_param(url, self.offset_query_param, offset) + + def get_html_context(self): + base_url = self.request.build_absolute_uri() + 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 + # plus the number of pages up to the current offset. + # When offset is not strictly divisible by the limit then we may + # end up introducing an extra page as an artifact. + final = ( + _divide_with_ceil(self.count - self.offset, self.limit) + + _divide_with_ceil(self.offset, self.limit) + ) + + def page_number_to_url(page_number): + if page_number == 1: + return remove_query_param(base_url, self.offset_query_param) + else: + offset = self.offset + ((page_number - current) * self.limit) + return replace_query_param(base_url, self.offset_query_param, offset) + + page_numbers = _get_displayed_page_numbers(current, final) + page_links = _get_page_links(page_numbers, current, page_number_to_url) + + return { + 'previous_url': self.get_previous_link(), + 'next_url': self.get_next_link(), + 'page_links': page_links + } + + def to_html(self): + template = loader.get_template(self.template) + context = Context(self.get_html_context()) + return template.render(context) |