django/docs/pagination.txt

==========
Pagination
==========

**New in Django development version**

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 the module ``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
    >>> 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()
    3
    >>> 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):
    ...
    InvalidPage
    >>> p.page(3)
    Traceback (most recent call last):
    ...
    InvalidPage

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.

``Paginator`` objects
=====================

Methods
-------

``page(number)`` -- Returns a ``Page`` object with the given 1-based index.
Raises ``InvalidPage`` if the given page number doesn't exist.

Attributes
----------

``count`` -- The total number of objects, across all pages.

``num_pages`` -- The total number of pages.

``page_range`` -- A 1-based range of page numbers, e.g., ``[1, 2, 3, 4]``.

``InvalidPage`` exceptions
==========================

The ``page()`` method raises ``InvalidPage`` 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:

``PageNotAnInteger`` -- Raised when ``page()`` is given a value that isn't an integer.

``EmptyPage`` -- 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
================

Methods
-------

``has_next()`` -- Returns ``True`` if there's a next page.

``has_previous()`` -- Returns ``True`` if there's a previous page.

``has_other_pages()`` -- Returns ``True`` if there's a next *or* previous page.

``next_page_number()`` -- Returns the next page number. Note that this is
"dumb" and will return the next page number regardless of whether a subsequent
page exists.

``previous_page_number()`` -- Returns the previous page number. Note that this
is "dumb" and will return the previous page number regardless of whether a
previous page exists.

``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
``start_index()`` would return ``3``.

``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
``end_index()`` would return ``4``.

Attributes
----------

``object_list`` -- The list of objects on this page.

``number`` -- The 1-based page number for this page.

``paginator`` -- The associated ``Paginator`` object.