Pagination¶
Django provides a few classes that help you manage paginated data – that is,
data that’s split across several pages, with “Previous/Next” links. These
classes live in django/core/paginator.py
.
Example¶
Give Paginator
a list of objects, plus the number of items you’d like to
have on each page, and it gives you methods for accessing the items for each
page:
>>> from django.core.paginator import Paginator
>>> objects = ['john', 'paul', 'george', 'ringo']
>>> p = Paginator(objects, 2)
>>> p.count
4
>>> p.num_pages
2
>>> type(p.page_range) # `<type 'rangeiterator'>` in Python 2.
<class 'range_iterator'>
>>> p.page_range
range(1, 3)
>>> page1 = p.page(1)
>>> page1
<Page 1 of 2>
>>> page1.object_list
['john', 'paul']
>>> page2 = p.page(2)
>>> page2.object_list
['george', 'ringo']
>>> page2.has_next()
False
>>> page2.has_previous()
True
>>> page2.has_other_pages()
True
>>> page2.next_page_number()
Traceback (most recent call last):
...
EmptyPage: That page contains no results
>>> page2.previous_page_number()
1
>>> page2.start_index() # The 1-based index of the first item on this page
3
>>> page2.end_index() # The 1-based index of the last item on this page
4
>>> p.page(0)
Traceback (most recent call last):
...
EmptyPage: That page number is less than 1
>>> p.page(3)
Traceback (most recent call last):
...
EmptyPage: That page contains no results
Note
Note that you can give Paginator
a list/tuple, a Django QuerySet
,
or any other object with a count()
or __len__()
method. When
determining the number of objects contained in the passed object,
Paginator
will first try calling count()
, then fallback to using
len()
if the passed object has no count()
method. This allows
objects such as Django’s QuerySet
to use a more efficient count()
method when available.
Using Paginator
in a view¶
Here’s a slightly more complex example using Paginator
in a view to
paginate a queryset. We give both the view and the accompanying template to
show how you can display the results. This example assumes you have a
Contacts
model that has already been imported.
The view function looks like this:
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
from django.shortcuts import render
def listing(request):
contact_list = Contacts.objects.all()
paginator = Paginator(contact_list, 25) # Show 25 contacts per page
page = request.GET.get('page')
try:
contacts = paginator.page(page)
except PageNotAnInteger:
# If page is not an integer, deliver first page.
contacts = paginator.page(1)
except EmptyPage:
# If page is out of range (e.g. 9999), deliver last page of results.
contacts = paginator.page(paginator.num_pages)
return render(request, 'list.html', {'contacts': contacts})
In the template list.html
, you’ll want to include navigation between
pages along with any interesting information from the objects themselves:
{% for contact in contacts %}
{# Each "contact" is a Contact model object. #}
{{ contact.full_name|upper }}<br />
...
{% endfor %}
<div class="pagination">
<span class="step-links">
{% if contacts.has_previous %}
<a href="?page={{ contacts.previous_page_number }}">previous</a>
{% endif %}
<span class="current">
Page {{ contacts.number }} of {{ contacts.paginator.num_pages }}.
</span>
{% if contacts.has_next %}
<a href="?page={{ contacts.next_page_number }}">next</a>
{% endif %}
</span>
</div>
Paginator
objects¶
The Paginator
class has this constructor:
Required arguments¶
object_list
A list, tuple,
QuerySet
, or other sliceable object with acount()
or__len__()
method. For consistent pagination,QuerySet
s should be ordered, e.g. with anorder_by()
clause or with a defaultordering
on the model.Performance issues paginating large
QuerySet
sIf you’re using a
QuerySet
with a very large number of items, requesting high page numbers might be slow on some databases, because the resultingLIMIT
/OFFSET
query needs to count the number ofOFFSET
records which takes longer as the page number gets higher.per_page
- The maximum number of items to include on a page, not including orphans
(see the
orphans
optional argument below).
Optional arguments¶
orphans
- Use this when you don’t want to have a last page with very few items.
If the last page would normally have a number of items less than or equal
to
orphans
, then those items will be added to the previous page (which becomes the last page) instead of leaving the items on a page by themselves. For example, with 23 items,per_page=10
, andorphans=3
, there will be two pages; the first page with 10 items and the second (and last) page with 13 items.orphans
defaults to zero, which means pages are never combined and the last page may have one item. allow_empty_first_page
- Whether or not the first page is allowed to be empty. If
False
andobject_list
is empty, then anEmptyPage
error will be raised.
Methods¶
-
Paginator.
page
(number)[source]¶ Returns a
Page
object with the given 1-based index. RaisesInvalidPage
if the given page number doesn’t exist.
Attributes¶
-
Paginator.
count
¶ The total number of objects, across all pages.
Note
When determining the number of objects contained in
object_list
,Paginator
will first try callingobject_list.count()
. Ifobject_list
has nocount()
method, thenPaginator
will fallback to usinglen(object_list)
. This allows objects, such as Django’sQuerySet
, to use a more efficientcount()
method when available.
-
Paginator.
num_pages
¶ The total number of pages.
-
Paginator.
page_range
¶ A 1-based range iterator of page numbers, e.g. yielding
[1, 2, 3, 4]
.
InvalidPage
exceptions¶
-
exception
InvalidPage
[source]¶ A base class for exceptions raised when a paginator is passed an invalid page number.
The Paginator.page()
method raises an exception if the requested page is
invalid (i.e., not an integer) or contains no objects. Generally, it’s enough
to catch the InvalidPage
exception, but if you’d like more granularity,
you can catch either of the following exceptions:
-
exception
EmptyPage
[source]¶ Raised when
page()
is given a valid value but no objects exist on that page.
Both of the exceptions are subclasses of InvalidPage
, so you can handle
them both with a simple except InvalidPage
.
Page
objects¶
You usually won’t construct Page
objects by hand – you’ll get them
using Paginator.page()
.
-
class
Page
(object_list, number, paginator)[source]¶ A page acts like a sequence of
Page.object_list
when usinglen()
or iterating it directly.
Methods¶
-
Page.
next_page_number
()[source]¶ Returns the next page number. Raises
InvalidPage
if next page doesn’t exist.
-
Page.
previous_page_number
()[source]¶ Returns the previous page number. Raises
InvalidPage
if previous page doesn’t exist.
-
Page.
start_index
()[source]¶ Returns the 1-based index of the first object on the page, relative to all of the objects in the paginator’s list. For example, when paginating a list of 5 objects with 2 objects per page, the second page’s
start_index()
would return3
.
-
Page.
end_index
()[source]¶ Returns the 1-based index of the last object on the page, relative to all of the objects in the paginator’s list. For example, when paginating a list of 5 objects with 2 objects per page, the second page’s
end_index()
would return4
.