Django_实现翻页功能

朱雀 2021-09-24 13:14 517阅读 0赞

Django提供了翻页器。用Django的Paginator类实现

#### 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 }}">上一页</a></li>
            {% else %}
            <li class="previous disabled"><a href="#">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 }}">{
       { num }}</a></li>
                {% else %}
                    <li class="item"><a href="/apitest_manage/?page={ { num }}">{
       { 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 }}">下一页</a></li>
            {% else %}
                <li class="next disabled"><a href="#">下一页</a></li>
            {% endif %}
    
        </ul>
    </div>

#### 三、效果展示![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zODg1MTk3MA_size_16_color_FFFFFF_t_70] ####

#### 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

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zODg1MTk3MA_size_16_color_FFFFFF_t_70]: /images/20210923/5dc1330ee39b457cad53b1d3a3c597dc.png