==========
Pagination
==========
.. module:: django.core.paginator
:synopsis: Classes to help you easily manage paginated data.
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 :file:`django/core/paginator.py`.
Example
=======
Give :class:`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
>>> p.page_range
[1, 2]
>>> 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 :class:`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
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_to_response('list.html', {"contacts": contacts})
In the template :file:`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 :class:`Paginator` class has this constructor:
.. class:: Paginator(object_list, per_page, orphans=0, allow_empty_first_page=True)
Required arguments
------------------
``object_list``
A list, tuple, Django ``QuerySet``, or other sliceable object with a
``count()`` or ``__len__()`` method.
``per_page``
The maximum number of items to include on a page, not including orphans
(see the ``orphans`` optional argument below).
Optional arguments
------------------
``orphans``
The minimum number of items allowed on the last page, defaults to zero.
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``, and
``orphans=3``, there will be two pages; the first page with 10 items and
the second (and last) page with 13 items.
``allow_empty_first_page``
Whether or not the first page is allowed to be empty. If ``False`` and
``object_list`` is empty, then an ``EmptyPage`` error will be raised.
Methods
-------
.. method:: Paginator.page(number)
Returns a :class:`Page` object with the given 1-based index. Raises
:exc:`InvalidPage` if the given page number doesn't exist.
Attributes
----------
.. attribute:: 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 calling ``object_list.count()``. If
``object_list`` has no ``count()`` method, then ``Paginator`` will
fallback to using ``len(object_list)``. This allows objects, such as
Django's ``QuerySet``, to use a more efficient ``count()`` method when
available.
.. attribute:: Paginator.num_pages
The total number of pages.
.. attribute:: Paginator.page_range
A 1-based range of page numbers, e.g., ``[1, 2, 3, 4]``.
``InvalidPage`` exceptions
==========================
.. exception:: InvalidPage
A base class for exceptions raised when a paginator is passed an invalid
page number.
The :meth:`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 trap the ``InvalidPage`` exception, but if you'd like more granularity, you
can trap either of the following exceptions:
.. exception:: PageNotAnInteger
Raised when ``page()`` is given a value that isn't an integer.
.. exception:: EmptyPage
Raised when ``page()`` is given a valid value but no objects exist on that
page.
Both of the exceptions are subclasses of :exc:`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 :meth:`Paginator.page`.
.. class:: Page(object_list, number, paginator)
A page acts like a sequence of :attr:`Page.object_list` when using
``len()`` or iterating it directly.
Methods
-------
.. method:: Page.has_next()
Returns ``True`` if there's a next page.
.. method:: Page.has_previous()
Returns ``True`` if there's a previous page.
.. method:: Page.has_other_pages()
Returns ``True`` if there's a next *or* previous page.
.. method:: Page.next_page_number()
Returns the next page number.
.. versionchanged:: 1.5
Raises :exc:`InvalidPage` if next page doesn't exist.
.. method:: Page.previous_page_number()
Returns the previous page number.
.. versionchanged:: 1.5
Raises :exc:`InvalidPage` if previous page doesn't exist.
.. method:: Page.start_index()
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
:meth:`~Page.start_index` would return ``3``.
.. method:: Page.end_index()
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
:meth:`~Page.end_index` would return ``4``.
Attributes
----------
.. attribute:: Page.object_list
The list of objects on this page.
.. attribute:: Page.number
The 1-based page number for this page.
.. attribute:: Page.paginator
The associated :class:`Paginator` object.
