Paginator

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.

Paginator class

class Paginator(object_list, per_page, orphans=0, allow_empty_first_page=True)

A paginator acts like a sequence of Page when using len() or iterating it directly.

Support for iterating over Paginator was added.

Paginator.object_list

Required. A list, tuple, QuerySet, or other sliceable object with a count() or __len__() method. For consistent pagination, QuerySets should be ordered, e.g. with an order_by() clause or with a default ordering on the model.

Performance issues paginating large QuerySets

If you're using a QuerySet with a very large number of items, requesting high page numbers might be slow on some databases, because the resulting LIMIT/OFFSET query needs to count the number of OFFSET records which takes longer as the page number gets higher.

Paginator.per_page
Required. The maximum number of items to include on a page, not including orphans (see the orphans optional argument below).
Paginator.orphans
Optional. 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. orphans defaults to zero, which means pages are never combined and the last page may have one item.
Paginator.allow_empty_first_page
Optional. 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.

方法

Paginator.get_page(number)

Returns a Page object with the given 1-based index, while also handling out of range and invalid page numbers.

If the page isn't a number, it returns the first page. If the page number is negative or greater than the number of pages, it returns the last page.

Raises an EmptyPage exception only if you specify Paginator(..., allow_empty_first_page=False) and the object_list is empty.

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


属性

Paginator.count

The total number of objects, across all pages.

注解

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 fall back to using len(object_list). This allows objects, such as QuerySet, to use a more efficient count() 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].


Page class

You usually won't construct Page objects by hand -- you'll get them by iterating Paginator, or by using Paginator.page().

class Page(object_list, number, paginator)
A page acts like a sequence of Page.object_list when using len() or iterating it directly.

方法

Page.has_next()
Returns True if there's a next page.
Page.has_previous()
Returns True if there's a previous page.
Page.has_other_pages()
Returns True if there's a next or previous page.
Page.next_page_number()
Returns the next page number. Raises InvalidPage if next page doesn't exist.
Page.previous_page_number()
Returns the previous page number. Raises InvalidPage if previous page doesn't exist.
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 start_index() would return 3.
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 end_index() would return 4.


属性

Page.object_list
此页上的对象列表。
Page.number
此页的基于 1 的页码。
Page.paginator
关联的 Paginator 对象。


例外

exception InvalidPage
当paginator对象试图访问无效页码时引发异常的基类。

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 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 InvalidPage, so you can handle them both with except InvalidPage.