Django paginator 分页详解

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Abstract

Django提供了一系列类来帮助你管理分页数据。这些类位于django/core/paginator.py

测试

root@pts/0 # python
Python 3.5.2 (default, Aug  8 2017, 15:35:13)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from django.core.paginator import Paginator

## 作为测试分页的对象
>>> objects = ['post1', 'post2', 'post3', 'post4', 'post5', 'post6', 'post7']
## 期望按照每页三个对象来实现分页
>>> paginator = Paginator(objects, 3)
## 输入paginator.  然后连续按两次 tab 键，展示 paginator 对应的方法属性等
>>> paginator.
paginator.__class__(                      paginator.__le__(                         paginator.__weakref__
paginator.__delattr__(                    paginator.__lt__(                         paginator._check_object_list_is_ordered(
paginator.__dict__                        paginator.__module__                      paginator._get_page(
paginator.__dir__(                        paginator.__ne__(                         paginator.allow_empty_first_page
paginator.__doc__                         paginator.__new__(                        paginator.count
paginator.__eq__(                         paginator.__reduce__(                     paginator.num_pages
paginator.__format__(                     paginator.__reduce_ex__(                  paginator.object_list
paginator.__ge__(                         paginator.__repr__(                       paginator.orphans
paginator.__getattribute__(               paginator.__setattr__(                    paginator.page(
paginator.__gt__(                         paginator.__sizeof__(                     paginator.page_range
paginator.__hash__(                       paginator.__str__(                        paginator.per_page
paginator.__init__(                       paginator.__subclasshook__(               paginator.validate_number(

## 要分页的总对象数
>>> paginator.count
7
>>> paginator.object_list
['post1', 'post2', 'post3', 'post4', 'post5', 'post6', 'post7']

## 总共可以分页数，也就是总共可以分成多少页
>>> paginator.num_pages
3
## 页码取值范围
>>> paginator.page_range
range(1, 4)
## 每页几个对象
>>> paginator.per_page
3

## 取第2页， 或者第N页`paginator.page(N)`
>>> page2 = paginator.page(2)
## page2 的属性和方法
>>> page2.
page2.__abstractmethods__          page2.__le__(                      page2._abc_cache
page2.__class__(                   page2.__len__(                     page2._abc_negative_cache
page2.__contains__(                page2.__lt__(                      page2._abc_negative_cache_version
page2.__delattr__(                 page2.__module__                   page2._abc_registry
page2.__dict__                     page2.__ne__(                      page2.count(
page2.__dir__(                     page2.__new__(                     page2.end_index(
page2.__doc__                      page2.__reduce__(                  page2.has_next(
page2.__eq__(                      page2.__reduce_ex__(               page2.has_other_pages(
page2.__format__(                  page2.__repr__(                    page2.has_previous(
page2.__ge__(                      page2.__reversed__(                page2.index(
page2.__getattribute__(            page2.__setattr__(                 page2.next_page_number(
page2.__getitem__(                 page2.__sizeof__(                  page2.number
page2.__gt__(                      page2.__slots__                    page2.object_list
page2.__hash__(                    page2.__str__(                     page2.paginator
page2.__init__(                    page2.__subclasshook__(            page2.previous_page_number(
page2.__iter__(                    page2.__weakref__                  page2.start_index(

## 第2页含有的对象列表
>>> page2.object_list
['post4', 'post5', 'post6']

## 从最上面我们知道，总共有7个对象，每页三个对象，我们总共分成3个页面，第二个页面在中间
## 所有第二页有next和previous， 并且可以得到Next 和 previous 的页码值
>>> page2.has_next()
True
>>> page2.next_page_number()
3
>>> page2.has_previous()
True
>>> page2.previous_page_number()
1
>>> page2.has_other_pages()
True

## 第二页开始和结束的对象索引
>>> page2.start_index()
4
>>> page2.end_index()
6
>>>

## 针对该测试例子。我们知道0和4页肯定是不存在， 所以出现 emptypage 异常
## 所以一般页面不存在或者页面无效之类的异常。我们都会让其跳转到第一页
>>> paginator.page(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/root/.pyenv/versions/blog/lib/python3.5/site-packages/django/core/paginator.py", line 57, in page
    number = self.validate_number(number)
  File "/root/.pyenv/versions/blog/lib/python3.5/site-packages/django/core/paginator.py", line 45, in validate_number
    raise EmptyPage(_('That page number is less than 1'))
django.core.paginator.EmptyPage: <exception str() failed>
>>> paginator.page(4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/root/.pyenv/versions/blog/lib/python3.5/site-packages/django/core/paginator.py", line 57, in page
    number = self.validate_number(number)
  File "/root/.pyenv/versions/blog/lib/python3.5/site-packages/django/core/paginator.py", line 50, in validate_number
    raise EmptyPage(_('That page contains no results'))
django.core.paginator.EmptyPage: <exception str() failed>
>>>

参考

https://docs.djangoproject.com/en/1.11/topics/pagination/