From d4d1a22730eecd207d0e656161d24a52284112bf Mon Sep 17 00:00:00 2001 From: Jacob Kaplan-Moss Date: Tue, 7 Nov 2006 04:44:27 +0000 Subject: [PATCH] Fixed #2575: ObjectPaginator now accepts a "orphans" option to prevent pages with only a few items. Thanks, SmileyChris. git-svn-id: http://code.djangoproject.com/svn/django/trunk@4041 bcc190cf-cafb-0310-a4f2-bffc1f526a37 --- django/core/paginator.py | 75 ++++++++++++++------------- tests/modeltests/pagination/models.py | 13 +++++ 2 files changed, 51 insertions(+), 37 deletions(-) diff --git a/django/core/paginator.py b/django/core/paginator.py index 026fe0a675..380808a3dd 100644 --- a/django/core/paginator.py +++ b/django/core/paginator.py @@ -1,54 +1,46 @@ -from math import ceil - class InvalidPage(Exception): pass class ObjectPaginator(object): """ - This class makes pagination easy. Feed it a QuerySet, plus the number of - objects you want on each page. Then read the hits and pages properties to + This class makes pagination easy. Feed it a QuerySet or list, plus the number + of objects you want on each page. Then read the hits and pages properties to see how many pages it involves. Call get_page with a page number (starting at 0) to get back a list of objects for that page. Finally, check if a page number has a next/prev page using has_next_page(page_number) and has_previous_page(page_number). + + Use orphans to avoid small final pages. For example: + 13 records, num_per_page=10, orphans=2 --> pages==2, len(self.get_page(0))==10 + 12 records, num_per_page=10, orphans=2 --> pages==1, len(self.get_page(0))==12 """ - def __init__(self, query_set, num_per_page): + def __init__(self, query_set, num_per_page, orphans=0): self.query_set = query_set self.num_per_page = num_per_page - self._hits, self._pages = None, None - self._has_next = {} # Caches page_number -> has_next_boolean + self.orphans = orphans + self._hits = self._pages = None - def get_page(self, page_number): + def validate_page_number(self, page_number): try: page_number = int(page_number) except ValueError: raise InvalidPage - if page_number < 0: + if page_number < 0 or page_number > self.pages - 1: raise InvalidPage + return page_number - # Retrieve one extra record, and check for the existence of that extra - # record to determine whether there's a next page. - limit = self.num_per_page + 1 - offset = page_number * self.num_per_page - - object_list = list(self.query_set[offset:offset+limit]) - - if not object_list: - raise InvalidPage - - self._has_next[page_number] = (len(object_list) > self.num_per_page) - return object_list[:self.num_per_page] + def get_page(self, page_number): + page_number = self.validate_page_number(page_number) + bottom = page_number * self.num_per_page + top = bottom + self.num_per_page + if top + self.orphans >= self.hits: + top = self.hits + return self.query_set[bottom:top] def has_next_page(self, page_number): "Does page $page_number have a 'next' page?" - if not self._has_next.has_key(page_number): - if self._pages is None: - offset = (page_number + 1) * self.num_per_page - self._has_next[page_number] = len(self.query_set[offset:offset+1]) > 0 - else: - self._has_next[page_number] = page_number < (self.pages - 1) - return self._has_next[page_number] + return page_number < self.pages - 1 def has_previous_page(self, page_number): return page_number > 0 @@ -58,8 +50,7 @@ class ObjectPaginator(object): Returns the 1-based index of the first object on the given page, relative to total objects found (hits). """ - if page_number == 0: - return 1 + page_number = self.validate_page_number(page_number) return (self.num_per_page * page_number) + 1 def last_on_page(self, page_number): @@ -67,20 +58,30 @@ class ObjectPaginator(object): Returns the 1-based index of the last object on the given page, relative to total objects found (hits). """ - if page_number == 0 and self.num_per_page >= self._hits: - return self._hits - elif page_number == (self._pages - 1) and (page_number + 1) * self.num_per_page > self._hits: - return self._hits - return (page_number + 1) * self.num_per_page + page_number = self.validate_page_number(page_number) + page_number += 1 # 1-base + if page_number == self.pages: + return self.hits + return page_number * self.num_per_page def _get_hits(self): if self._hits is None: - self._hits = self.query_set.count() + # Try .count() or fall back to len(). + try: + self._hits = int(self.query_set.count()) + except (AttributeError, TypeError, ValueError): + # AttributeError if query_set has no object count. + # TypeError if query_set.count() required arguments. + # ValueError if int() fails. + self._hits = len(self.query_set) return self._hits def _get_pages(self): if self._pages is None: - self._pages = int(ceil(self.hits / float(self.num_per_page))) + hits = (self.hits - 1 - self.orphans) + if hits < 1: + hits = 0 + self._pages = hits // self.num_per_page + 1 return self._pages hits = property(_get_hits) diff --git a/tests/modeltests/pagination/models.py b/tests/modeltests/pagination/models.py index ea2385dc79..3319b5cafa 100644 --- a/tests/modeltests/pagination/models.py +++ b/tests/modeltests/pagination/models.py @@ -64,4 +64,17 @@ True >>> paginator.last_on_page(1) 9 +# Add a few more records to test out the orphans feature. +>>> for x in range(10, 13): +... Article(headline="Article %s" % x, pub_date=datetime(2006, 10, 6)).save() + +# With orphans set to 3 and 10 items per page, we should get all 12 items on a single page: +>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=3) +>>> paginator.pages +1 + +# With orphans only set to 1, we should get two pages: +>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=1) +>>> paginator.pages +2 """}