14 优化分页展示

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本教程来源于B站杨仕航Django2.0开发视频教程，如需转载，必须注明来源！

1.优化分页展示

上一讲中的分页展示存在的问题如下：
- 无法知道当前是在哪一页，如下图所示。
- 如果每2篇文章当作一页，就会使得分页展示很长。
  
  分页展示存在的问题.png
  
  友好的分页展示.png

修改blog文件目录下的templates模板文件夹下的blog_list.html文件，在代码{% for page_num in page_of_blogs.paginator.page_range %}下方添加如下代码，从而使当前页高亮显示：

{% if page_num == page_of_blogs.number %}
    <li class="active">
        <span>{{ page_num }}</span>
    </li>
{% else %}
    <li>
        <a href="?page={{ page_num }}">{{ page_num }}</a>
    </li>
{% endif %}

仅显示当前页前后两页的页码，不显示所有的页码。因此对blog_list.html文件进行修改，因为代码{% for page_num in page_of_blogs.paginator.page_range %}是对所有博客都进行了遍历，所以要修改blog文件目录下的views.py文件，在blog_list()函数中添加仅显示当前页前后两页的页码的代码，如下所示：

from django.shortcuts import render_to_response, get_object_or_404
from django.core.paginator import Paginator
from .models import Blog, BlogType
# Create your views here.


def blog_list(request):
    blogs_all_list = Blog.objects.all()
    paginator = Paginator(blogs_all_list, 2)  # 每2篇进行一次分页
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    page_range = [current_page_num - 2, current_page_num - 1, current_page_num,
                  current_page_num + 1, current_page_num + 2, ]

    context = {}
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blog_list.html', context)


def blog_detail(request, blog_pk):
    context = {}
    context['blog'] = get_object_or_404(Blog, pk=blog_pk)
    return render_to_response('blog/blog_detail.html', context)

接着修改blog_list.html文件中的{% for page_num in page_of_blogs.paginator.page_range %}为{% for page_num in page_range %}

当点击第1页或第17页时，就会出现如下的错误。因此修改blog文件目录下的views.py文件中的blog_list()函数。如下所示：

from django.shortcuts import render_to_response, get_object_or_404
from django.core.paginator import Paginator
from .models import Blog, BlogType
# Create your views here.


def blog_list(request):
    blogs_all_list = Blog.objects.all()
    paginator = Paginator(blogs_all_list, 2)  # 每2篇进行一次分页
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    # 获取当前页码前后各两页的页码范围
    page_range = list(range(max(current_page_num - 2, 1), current_page_num)) + \
        list(range(current_page_num, min(
            current_page_num + 2, paginator.num_pages) + 1))
    context = {}
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blog_list.html', context)


def blog_detail(request, blog_pk):
    context = {}
    context['blog'] = get_object_or_404(Blog, pk=blog_pk)
    return render_to_response('blog/blog_detail.html', context)

错误.png

正确.png

当点击中间某一页时，需要将第一页和最后一页的页码也显示出来。因此，继续修改blog文件目录下的views.py文件中的blog_list()函数。如下所示：

from django.shortcuts import render_to_response, get_object_or_404
from django.core.paginator import Paginator
from .models import Blog, BlogType
# Create your views here.


def blog_list(request):
    blogs_all_list = Blog.objects.all()
    paginator = Paginator(blogs_all_list, 2)  # 每2篇进行一次分页
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    # 获取当前页码前后各两页的页码范围
    page_range = list(range(max(current_page_num - 2, 1), current_page_num)) + \
        list(range(current_page_num, min(
            current_page_num + 2, paginator.num_pages) + 1))

    if page_range[0] != 1:
        page_range.insert(0, 1)
    if page_range[-1] != paginator.num_pages:
        page_range.append(paginator.num_pages)

    context = {}
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blog_list.html', context)


def blog_detail(request, blog_pk):
    context = {}
    context['blog'] = get_object_or_404(Blog, pk=blog_pk)
    return render_to_response('blog/blog_detail.html', context)

当点击中间某一页时，需要将第一页和最后一页的页码也显示出来.png

通过上图我们可以发现，第7页与最后一页之间相差太多。它们之间可以用省略号表示两者之间相差很多页。因此，继续修改blog文件目录下的views.py文件中的blog_list()函数。如下所示：

from django.shortcuts import render_to_response, get_object_or_404
from django.core.paginator import Paginator
from .models import Blog, BlogType
# Create your views here.


def blog_list(request):
    blogs_all_list = Blog.objects.all()
    paginator = Paginator(blogs_all_list, 2)  # 每2篇进行一次分页
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    # 获取当前页码前后各两页的页码范围
    page_range = list(range(max(current_page_num - 2, 1), current_page_num)) + \
        list(range(current_page_num, min(
            current_page_num + 2, paginator.num_pages) + 1))
    # 加上省略页码标记
    if page_range[0] - 1 >= 2:
        page_range.insert(0, '...')
    if paginator.num_pages - page_range[-1] >= 2:
        page_range.append('...')

    # 加上首页和尾页
    if page_range[0] != 1:
        page_range.insert(0, 1)
    if page_range[-1] != paginator.num_pages:
        page_range.append(paginator.num_pages)

    context = {}
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blog_list.html', context)


def blog_detail(request, blog_pk):
    context = {}
    context['blog'] = get_object_or_404(Blog, pk=blog_pk)
    return render_to_response('blog/blog_detail.html', context)

正确显示.png

当点击上图中的省略号时，会出现下图中的情况。因此，需要对blog文件目录下的blog_list.html模板文件进行修改，即对全部页码部分进行修改，如下所示：

{# 全部页码 #}
{% for page_num in page_range %}

    {% if page_num == page_of_blogs.number %}
        <li class="active">
            <span>{{ page_num }}</span>
        </li>
    {% else %}
        {% if page_num == '...' %}
            <li>
                <span>{{ page_num }}</span>
            </li>
        {% else %}
            <li>
                <a href="?page={{ page_num }}">{{ page_num }}</a>
            </li>
        {% endif %}
    {% endif %}

{% endfor %}

点击省略号时，不应该发送请求.png

博客总数量在前端页面中的展示位置需要重新布局，因此对blog文件目录下的blog_list.html模板文件进行修改，即对(一共有34篇博客)进行修改，给div盒子增加一个类名为paginator，同时增加一个p标签，当中放入共有{{ page_of_blogs.paginator.count }}篇博客，当前第{{ page_of_blogs.number }}页，共{{ page_of_blogs.paginator.num_pages }}页，如下所示：

{% extends 'base.html' %}
{# blog_list.html文件内容 #}
{# 页面标题 #}
{% block title %}我的网站{% endblock %}
{% block nav_blog_active %}active{% endblock %}

{% load staticfiles %}
{% block header_extends %}
    <link rel="stylesheet" href="{% static 'blog/blog.css' %}">
{% endblock %}

{# 页面内容 #}
{% block content %}
    <div class="container">
        <div class="row">
            <div class="col-xs-12 col-sm-8 col-md-9 col-lg-10">
                <div class="panel panel-default">
                    <div class="panel-heading">
                        {% block blog_list_title %}博客列表{% endblock %}
                    </div>
                    <div class="panel-body">
                        <!-- 下一行中的blogs来自于views.py中的context['blogs'] = Blog.objects.all() -->
                        {% for blog in blogs %}
                            <div class="blog">
                                <!-- 下一行中的blog.title来自于models.py中的title = models.CharField(max_length=50) -->
                                <h3><a href="{% url 'blog_detail' blog.pk %}">{{ blog.title }}</a></h3>
                                <p class="blog-info">
                                    <span class="glyphicon glyphicon-tag"></span><a href="{% url 'blogs_with_type' blog.blog_type.pk %}">{{ blog.blog_type }}</a> &nbsp&nbsp&nbsp
                                    <span class="glyphicon glyphicon-time"></span>{{ blog.created_time|date:"Y-m-d" }}
                                </p>
                                <p>{{ blog.content|truncatechars:120 }}</p>
                            </div>
                        {% empty %}
                           <div class="bog">
                                <h3>暂无博客，敬请期待</h3>
                           </div>
                        {% endfor %}
                    </div>
                </div>
                <!-- 此处使用了bootstrp组件中的分页代码 -->
                <div class="paginator">
                    <ul class="pagination">
                        {# 上一页 #}
                        <li>
                            {% if page_of_blogs.has_previous %}
                                <a href="?page={{ page_of_blogs.previous_page_number }}" aria-label="Previous">
                                    <span aria-hidden="true">&laquo;</span>
                                </a>
                            {% else %}
                                <span aria-hidden="true">&laquo;</span>
                            {% endif %}

                        </li>

                        {# 全部页码 #}
                        {% for page_num in page_range %}

                            {% if page_num == page_of_blogs.number %}
                                <li class="active">
                                    <span>{{ page_num }}</span>
                                </li>
                            {% else %}
                                {% if page_num == '...' %}
                                    <li>
                                        <span>{{ page_num }}</span>
                                    </li>
                                {% else %}
                                    <li>
                                        <a href="?page={{ page_num }}">{{ page_num }}</a>
                                    </li>
                                {% endif %}
                            {% endif %}

                        {% endfor %}

                        {# 下一页 #}
                        <li>
                            {% if page_of_blogs.has_next %}
                                <a href="?page={{ page_of_blogs.next_page_number }}" aria-label="Next">
                                    <span aria-hidden="true">&raquo;</span>
                                </a>
                            {% else %}
                                <span aria-hidden="true">&raquo;</span>
                            {% endif %}
                        </li>
                    </ul>
                    <p>共有{{ page_of_blogs.paginator.count }}篇博客，当前第{{ page_of_blogs.number }}页，共{{ page_of_blogs.paginator.num_pages }}页</p>
                </div>
            </div>

            <div class="hidden-xs col-sm-4 col-md-3 col-lg-2">
                <div class="panel panel-default">
                    <div class="panel-heading">
                        博客分类
                    </div>
                    <div class="panel-body">
                        <ul class="blog-types">
                            {% for blog_type in blog_types %}
                                <li><a href="{% url 'blogs_with_type' blog_type.pk %}">{{ blog_type.type_name }}</a></li>
                            {% empty %}
                                <li>暂无分类</li>
                            {% endfor %}
                        </ul>
                    </div>
                </div>
            </div>
        </div>
    </div>

{% endblock %}

接着，对类名为paginator的div盒子进行css美化，打开blog文件目录下的static/blog文件夹中的blog.css，当中添加如下内容：
```
div.paginator {
    text-align: center;
}
```

美化后的页面.png

然后，对blog文件目录下views.py文件中的blogs_with_type()函数进行修改，修改后的函数内容如下所示：

def blogs_with_type(request, blog_type_pk):
    blog_type = get_object_or_404(BlogType, pk=blog_type_pk)
    blogs_all_list = Blog.objects.filter(blog_type=blog_type)
    paginator = Paginator(blogs_all_list, 2)  # 每2篇进行一次分页
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    # 获取当前页码前后各两页的页码范围
    page_range = list(range(max(current_page_num - 2, 1), current_page_num)) + \
        list(range(current_page_num, min(
            current_page_num + 2, paginator.num_pages) + 1))
    # 加上省略页码标记
    if page_range[0] - 1 >= 2:
        page_range.insert(0, '...')
    if paginator.num_pages - page_range[-1] >= 2:
        page_range.append('...')

    # 加上首页和尾页
    if page_range[0] != 1:
        page_range.insert(0, 1)
    if page_range[-1] != paginator.num_pages:
        page_range.append(paginator.num_pages)

    context = {}
    context['blog_type'] = blog_type
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blogs_with_type.html', context)

2.settings自定义设置

settings自定义设置.png

修改每页所展示的博客数量，首先在全局设置文件settings.py末尾处增加如下内容。
```
# 自定义参数
EACH_PAGE_BLOGS_NUMBER = 7
```

然后，修改blog文件目录下views.py文件中的和blog_list()和blogs_with_type()函数进行修改，修改后的函数内容如下所示：

from django.shortcuts import render_to_response, get_object_or_404
from django.core.paginator import Paginator
from django.conf import settings
from .models import Blog, BlogType
# Create your views here.


def blog_list(request):
    blogs_all_list = Blog.objects.all()
    paginator = Paginator(
        blogs_all_list, settings.EACH_PAGE_BLOGS_NUMBER)
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    # 获取当前页码前后各两页的页码范围
    page_range = list(range(max(current_page_num - 2, 1), current_page_num)) + \
        list(range(current_page_num, min(
            current_page_num + 2, paginator.num_pages) + 1))
    # 加上省略页码标记
    if page_range[0] - 1 >= 2:
        page_range.insert(0, '...')
    if paginator.num_pages - page_range[-1] >= 2:
        page_range.append('...')

    # 加上首页和尾页
    if page_range[0] != 1:
        page_range.insert(0, 1)
    if page_range[-1] != paginator.num_pages:
        page_range.append(paginator.num_pages)

    context = {}
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blog_list.html', context)


def blog_detail(request, blog_pk):
    context = {}
    context['blog'] = get_object_or_404(Blog, pk=blog_pk)
    return render_to_response('blog/blog_detail.html', context)


def blogs_with_type(request, blog_type_pk):
    blog_type = get_object_or_404(BlogType, pk=blog_type_pk)
    blogs_all_list = Blog.objects.filter(blog_type=blog_type)
    paginator = Paginator(blogs_all_list, settings.EACH_PAGE_BLOGS_NUMBER)
    page_num = request.GET.get('page', 1)  # 获取url的页码参数(GET请求)
    page_of_blogs = paginator.get_page(page_num)
    current_page_num = page_of_blogs.number  # 获取当前页码
    # 获取当前页码前后各两页的页码范围
    page_range = list(range(max(current_page_num - 2, 1), current_page_num)) + \
        list(range(current_page_num, min(
            current_page_num + 2, paginator.num_pages) + 1))
    # 加上省略页码标记
    if page_range[0] - 1 >= 2:
        page_range.insert(0, '...')
    if paginator.num_pages - page_range[-1] >= 2:
        page_range.append('...')

    # 加上首页和尾页
    if page_range[0] != 1:
        page_range.insert(0, 1)
    if page_range[-1] != paginator.num_pages:
        page_range.append(paginator.num_pages)

    context = {}
    context['blog_type'] = blog_type
    context['blogs'] = page_of_blogs.object_list
    context['page_of_blogs'] = page_of_blogs
    context['page_range'] = page_range
    context['blog_types'] = BlogType.objects.all()
    return render_to_response('blog/blogs_with_type.html', context)

最后，点击具体的某一种博客分类，将例如分类：Django旁边的统计博客数量的显示信息去掉。打开blog文件夹目录下的templates/blogs_with_type.html文件，修改其内容后的结果如下所示：

删除统计博客数量的显示信息.png

{% extends 'blog/blog_list.html' %}

{# blogs_with_type.html文件内容 #}

{# 页面标题 #}
{% block title %}
    {{ blog_type.type_name }}
{% endblock %}

{% block blog_list_title %}
    分类：{{ blog_type.type_name }}
    <a href="{% url 'blogs_with_type' blog_type.pk %}">查看全部博客</a>
{% endblock %}

修改后的结果.png