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Fixed #2575: ObjectPaginator now accepts a "orphans" option to preven…

…t pages with only a few items. Thanks, SmileyChris.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4041 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit d4d1a22730eecd207d0e656161d24a52284112bf 1 parent dabf036
@jacobian jacobian authored
Showing with 51 additions and 37 deletions.
  1. +38 −37 django/core/paginator.py
  2. +13 −0 tests/modeltests/pagination/models.py
View
75 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 @@ def first_on_page(self, page_number):
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 @@ def last_on_page(self, page_number):
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)
View
13 tests/modeltests/pagination/models.py
@@ -64,4 +64,17 @@ def __str__(self):
>>> 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
"""}
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