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django/docs/pagination.txt
Adrian Holovaty edb3381c7a Added docs/pagination.txt
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==========
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
``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]``.
``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.
``QuerySetPaginator`` objects
=============================
Use ``QuerySetPaginator`` instead of ``Paginator`` if you're paginating across
a ``QuerySet`` from Django's database API. This is slightly more efficient, and
there are no API differences between the two classes.
The legacy ``ObjectPaginator`` class
====================================
The ``Paginator`` and ``Page`` classes are new in the Django development
version, as of revision 7306. In previous versions, Django provided an
``ObjectPaginator`` class that offered similar functionality but wasn't as
convenient. This class still exists, for backwards compatibility, but Django
now issues a ``DeprecationWarning`` if you try to use it.