对于web应用开发而言，有一项功能是相当常见的，那就是分页，而这项功能最关键的作用，就是实现将数据分成一页一页的效果，这样每次就能阅读有限数量的数据，既降低了服务器压力又提高了阅读效率，而分页功能的实现必须实现两个小功能，分别是数据分页和翻页功能，接下来小编就以Django为例介绍一下Django如何实线分页，以及Django如何实现翻页功能吧。
一、views模块导入Paginator类实现数据分页
ApiTest/apiviews.py
每行都加了注释，希望有助于理解。
from django.shortcuts import render
from ApiTest.models import ApiTest
from django.contrib.auth.decorators import login_required
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger, InvalidPage
@login_required
def api_test_manage(request):
username = request.session.get('user', '')
# 获取所有接口测试数据
apitest_list = ApiTest.objects.all().order_by('id')
# 生成Paginator对象对数据分页，每页显示10条数据
paginator = Paginator(apitest_list,10)
# 使用request.GET.get()函数获取url中的page参数的数值。默认第1页
page = request.GET.get('page', 1)
# 把获取的当前页码数转换成整数类型
current_page = int(page)
try:
# 获取查询页数的接口数据列表，page()函数会判断page实参是否是有效数字。page()函数源码附在文章的最后
apitest_list = paginator.page(page)
except PageNotAnInteger:
apitest_list = paginator.page(1)
except (EmptyPage, InvalidPage):
# paginator.num_pages
apitest_list = paginator.page(paginator.num_pages)
return render(request, "apitest_manage.html", {'user': username, 'apitests': apitest_list})二、将views的数据渲染到前端模板上
在对应的html文件中加入此段代码即可。
<div class="container">
<ul class="pagination" id="pager">
{# 上一页链接 #}
{% if apitests.has_previous %}
<li class="previous"><a href="/apitest_manage/?page={{ apitests.previous_page_number }}" rel="external nofollow" >上一页</a></li>
{% else %}
<li class="previous disabled"><a href="#" rel="external nofollow" rel="external nofollow" >上一页</a></li>
{% endif %}
{# 中间数字显示 #}
{% for num in apitests.paginator.page_range %}
{% if num == currentPage %}
<li class="item active"><a href="/apitest_manage/?page={{ num }}" rel="external nofollow" rel="external nofollow" >{{ num }}</a></li>
{% else %}
<li class="item"><a href="/apitest_manage/?page={{ num }}" rel="external nofollow" rel="external nofollow" >{{ num }}</a></li>
{% endif %}
{% endfor %}
{# 下一页链接 #}
{% if apitests.has_next %} {# 如果有下一页，则正常显示下一页链接 #}
<li class="next"><a href="/apitest_manage/?page={{ apitests.next_page_number }}" rel="external nofollow" >下一页</a></li>
{% else %}
<li class="next disabled"><a href="#" rel="external nofollow" rel="external nofollow" >下一页</a></li>
{% endif %}
</ul>
</div>三、效果展示
四、Paginator类源码
此类主要用在views文件
class Paginator:
def __init__(self, object_list, per_page, orphans=0,
allow_empty_first_page=True):
self.object_list = object_list
self._check_object_list_is_ordered()
self.per_page = int(per_page)
self.orphans = int(orphans)
self.allow_empty_first_page = allow_empty_first_page
def validate_number(self, number):
"""Validate the given 1-based page number."""
try:
if isinstance(number, float) and not number.is_integer():
raise ValueError
number = int(number)
except (TypeError, ValueError):
raise PageNotAnInteger(_('That page number is not an integer'))
if number < 1:
raise EmptyPage(_('That page number is less than 1'))
if number > self.num_pages:
if number == 1 and self.allow_empty_first_page:
pass
else:
raise EmptyPage(_('That page contains no results'))
return number
def get_page(self, number):
"""
Return a valid page, even if the page argument isn't a number or isn't
in range.
"""
try:
number = self.validate_number(number)
except PageNotAnInteger:
number = 1
except EmptyPage:
number = self.num_pages
return self.page(number)
def page(self, number):
"""Return a Page object for the given 1-based page number."""
number = self.validate_number(number)
bottom = (number - 1) * self.per_page
top = bottom + self.per_page
if top + self.orphans >= self.count:
top = self.count
return self._get_page(self.object_list[bottom:top], number, self)
def _get_page(self, *args, **kwargs):
"""
Return an instance of a single page.
This hook can be used by subclasses to use an alternative to the
standard :cls:`Page` object.
"""
return Page(*args, **kwargs)
@cached_property
def count(self):
"""Return the total number of objects, across all pages."""
c = getattr(self.object_list, 'count', None)
if callable(c) and not inspect.isbuiltin(c) and method_has_no_args(c):
return c()
return len(self.object_list)
@cached_property
def num_pages(self):
"""Return the total number of pages."""
if self.count == 0 and not self.allow_empty_first_page:
return 0
hits = max(1, self.count - self.orphans)
return ceil(hits / self.per_page)
@property
def page_range(self):
"""
Return a 1-based range of pages for iterating through within
a template for loop.
"""
return range(1, self.num_pages + 1)
def _check_object_list_is_ordered(self):
"""
Warn if self.object_list is unordered (typically a QuerySet).
"""
ordered = getattr(self.object_list, 'ordered', None)
if ordered is not None and not ordered:
obj_list_repr = (
'{} {}'.format(self.object_list.model, self.object_list.__class__.__name__)
if hasattr(self.object_list, 'model')
else '{!r}'.format(self.object_list)
)
warnings.warn(
'Pagination may yield inconsistent results with an unordered '
'object_list: {}.'.format(obj_list_repr),
UnorderedObjectListWarning,
stacklevel=3
)五、Page类源码
此类主要用在html文件
class Page(collections.abc.Sequence):
def __init__(self, object_list, number, paginator):
self.object_list = object_list
self.number = number
self.paginator = paginator
def __repr__(self):
return '<Page %s of %s>' % (self.number, self.paginator.num_pages)
def __len__(self):
return len(self.object_list)
def __getitem__(self, index):
if not isinstance(index, (int, slice)):
raise TypeError(
'Page indices must be integers or slices, not %s.'
% type(index).__name__
)
# The object_list is converted to a list so that if it was a QuerySet
# it won't be a database hit per __getitem__.
if not isinstance(self.object_list, list):
self.object_list = list(self.object_list)
return self.object_list[index]
def has_next(self):
return self.number < self.paginator.num_pages
def has_previous(self):
return self.number > 1
def has_other_pages(self):
return self.has_previous() or self.has_next()
def next_page_number(self):
return self.paginator.validate_number(self.number + 1)
def previous_page_number(self):
return self.paginator.validate_number(self.number - 1)
def start_index(self):
"""
Return the 1-based index of the first object on this page,
relative to total objects in the paginator.
"""
# Special case, return zero if no items.
if self.paginator.count == 0:
return 0
return (self.paginator.per_page * (self.number - 1)) + 1
def end_index(self):
"""
Return the 1-based index of the last object on this page,
relative to total objects found (hits).
"""
# Special case for the last page because there can be orphans.
if self.number == self.paginator.num_pages:
return self.paginator.count
return self.number * self.paginator.per_page小结
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