10.Django高级之分页器组件

批量插入数据

模板层models.py

from django.db import models

class Books(models.Model):
    name = models.CharField(max_length=32)
    price = models.DecimalField(max_digits=8,decimal_places=2)
    publish = models.CharField(max_length=32)

建表别忘了执行数据库迁移命令哦

python3 manage.py makemigrations

python3 manage.py migrate

路由层urls.py

urlpatterns = [
    url(r'^books_page/', views.books_page), 
]

视图层views.py

# 往Book表里批量插入数据

def books_page(request):
   # 第一种方案，每循环一次，操作一下数据库，性能低（相当于进行了1000次的数据库链接）
    # for i in range(1000):
    #     book=models.Books.objects.create(name='图书%s'%i,price=i+10,publish='东京出版社')
    #
   # 第二种方案，批量插入
    book_list=[]  # 实例化对象放到列表里
    for i in range(1000):
        book=models.Books(name='图书%s'%i,price=i+10,publish='东京出版社')
        book_list.append(book)
    # bulk_create一次性插入，batch_size分批往里面插
    models.Books.objects.bulk_create(book_list,batch_size=100)

    return HttpResponse('ok')

# 当你想要批量插入数据的时候，使用ORM提供的 bulk_create 能够大大的减少操作时间

Django的分页器（paginator）

Django提供了一个新的类来帮助你管理分页数据，这个模块存放在django.core.paginator.py。其中有两个核心类，一个是Paginator类，另一个是Page类。

在页面显示分页数据，需要用到Django分页器组件

from django.core.paginator import Paginator

分页器的使用方法

urlpatterns = [
    url(r'^books_page/', views.books_page), 
]

路由层urls.py

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
    <link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/3.4.1/css/bootstrap.min.css" rel="stylesheet">
    <script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/3.4.1/js/bootstrap.min.js"></script>
</head>
<body>
<div>
    <table class="table table-striped">
        <thead>
        <tr>
            <th>id</th>
            <th>书名</th>
            <th>价格</th>
            <th>出版社</th>
        </tr>
        </thead>
        <tbody>
        {% for book in book_list %}
            <tr>
                <td>{{ book.id }}</td>
                <td>{{ book.name }}</td>
                <td>{{ book.price }}</td>
                <td>{{ book.publish }}</td>
            </tr>
        {% endfor %}

        </tbody>
    </table>
</div>

<div>

    <nav aria-label="Page navigation">
        <ul class="pagination">
            <li>
                <a href="#" aria-label="Previous">
                    <span aria-hidden="true">«</span>
                </a>
            </li>
            <li><a href="#">1</a></li>
            <li><a href="#">2</a></li>
            <li><a href="#">3</a></li>
            <li><a href="#">4</a></li>
            <li><a href="#">5</a></li>
            <li>
                <a href="#" aria-label="Next">
                    <span aria-hidden="true">»</span>
                </a>
            </li>
        </ul>
    </nav>
</div>

</body>
</html>

前端book_page.html

前端book_page.html

视图层views.py及使用方法

from django.shortcuts import render,HttpResponse,redirect
from django.core.paginator import Paginator
def books_page(request):
    book_list=models.Books.objects.all()  # 拿到所有的书籍
    paginator=Paginator(book_list,10)  # 实例化得到对象
    # Paginator对象的属性
    print(paginator.count) # 数据总条数
    print(paginator.num_pages) # 总页数
    print(paginator.per_page) # 每页显示条数
    print(paginator.page_range) # range(1, 101) 页码数可以从1拿到100
    print(paginator.page(2)) # page对象，拿出第2页
    # Page对象的属性和方法页
    page = paginator.page(2) # 当前所在页数
    print(page.has_next()) # 是否有下一页
    print(page.next_page_number()) # 下一页页码
    print(page.has_previous()) # 是否有上一页
    print(page.previous_page_number()) # 上一页页码
    print(page.object_list) # 分页之后的数据列表
    print(page.number)  # 当前页

    return render(request,'book_page.html',locals())

分页器终极用法

改吧改吧就能使哦

urlpatterns = [
    url(r'^books_page/', views.books_page),
]

urls.py

# 分页器的终极使用
def books_page(request):
    # 当前页码，用户访问首页默认是第一页，转成int类型
    current_num = int(request.GET.get('page_num', 1)) # 从前端获取page_num
    
    book_list = models.Books.objects.all()  # 拿到要展示的所有数据

    paginator = Paginator(book_list, 20) # 每页显示20条
    
    try:
        page = paginator.page(current_num) # 取到当前的页码数
    except Exception as e:
        current_num = 1  # 无论选择的大于或者小于强制等于1
        page = paginator.page(current_num)
        
    # 如果总页码数大于11
    if paginator.num_pages > 11:
        
        # 当前页码减5小于1，要生成1到12的列表（顾头不顾尾，共11个页码）
        if current_num - 5 < 1:
            page_range = range(1, 12)
            
        # 当前页码+5大于总页码，生成当前页码减10，到当前页码加1的列表（顾头不顾尾，共11个页码）
        elif current_num + 5 > paginator.num_pages:
            page_range = range(paginator.num_pages - 10, paginator.num_pages + 1)
            
        else: # 生成当前页码 - 5，到当前页码 + 6的列表
            page_range = range(current_num - 5, current_num + 6)
            
    # 其它情况，生成的列表就是pageinator的page_range
    else:
        page_range = paginator.page_range

    return render(request, 'book_page.html', locals())


'''
上一页 1 2 3 4 5 6 7 8 9 10 11 下一页

上一页 21 22 23 24 25 26 27 28 29 30 31 下一页

'''

views.py

views.py

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>book_page.html</title>
    <link rel="stylesheet" href="/static/bootstrap-3.3.7-dist/css/bootstrap.min.css">
    <script src="/static/bootstrap-3.3.7-dist/js/bootstrap.min.js"></script>
    <script src="/static/jquery-3.3.1.js"></script>

</head>
<body>
<div class="container-fluid">
    <div class="row">

        <div class="col-md-8 col-md-offset-2">
            <div class="panel panel-success">
                <div class="panel-heading">
                    <h3 class="panel-title">图书列表展示</h3>
                </div>
                <div class="panel-body">

                    <table class="table table-striped">
                        <thead>
                        <tr>
                            <th>id</th>
                            <th>书名</th>
                            <th>价格</th>
                            <th>出版社</th>
                        </tr>
                        </thead>
                        <tbody>
                        {% for book in page.object_list %}
                            <tr>
                                <td>{{ book.id }}</td>
                                <td>{{ book.name }}</td>
                                <td>{{ book.price }}</td>
                                <td>{{ book.publish }}</td>
                            </tr>
                        {% endfor %}

                        </tbody>
                    </table>
                    <div class="text-center">
                        <nav aria-label="Page navigation">
                            <ul class="pagination">
                                {% if page.has_previous %}
                                    <li>
                                        <a href="/books_page/?page_num={{ page.previous_page_number }}"
                                           aria-label="Previous">
                                            <span aria-hidden="true">«</span>
                                        </a>
                                    </li>
                                {% else %}
                                    <li class="disabled">
                                        <a href="" aria-label="Previous">
                                            <span aria-hidden="true">«</span>
                                        </a>
                                    </li>
                                {% endif %}
                                    {# 当前循环到的页码数，page_range是一个生成器对象 #}
                                {% for foo in page_range %}
                                    {# 如果点中的那个数字等于当前页码数，则渲染成蓝色 #}
                                    {% if current_num == foo %}
                                        <li class="active"><a href="/books_page/?page_num={{ foo }}">{{ foo }}</a></li>
                                    {% else %}
                                        {# 不等于就正常渲染 #}
                                        <li><a href="/books_page/?page_num={{ foo }}">{{ foo }}</a></li>
                                    {% endif %}
                                {% endfor %}
                                {% if page.has_next %}
                                    <li>
                                        <a href="/books_page/?page_num={{ page.next_page_number }}" aria-label="Next">
                                            <span aria-hidden="true">»</span>
                                        </a>
                                    </li>
                                {% else %}
                                    <li class="disabled">
                                        <a href="" aria-label="Next">
                                            <span aria-hidden="true">»</span>
                                        </a>
                                    </li>
                                {% endif %}
                            </ul>
                        </nav>
                    </div>

                </div>
            </div>
        </div>
    </div>

</div>

<div>

</div>

</body>
</html>

 books_page.html

books_page.html

自定义分页器的拷贝及使用（极力推荐）

当我们需要使用到非django内置的第三方功能或者组件代码的时候，我们一般情况下会创建一个名为utils的文件夹，在该文件夹内对模块进行功能性划分。eg：mypage.py

我们到了后期封装代码的时候，不再局限于函数，而是尽量朝面向对象去封装

将下面封装好的模板拷贝到utils文件夹下的mypage.py（自定义的名字随意取）

class Pagination(object):
    def __init__(self, current_page, all_count, per_page_num=2, pager_count=5):
        """
        封装分页相关数据
        :param current_page: 当前页
        :param all_count:    数据库中的数据总条数
        :param per_page_num: 每页显示的数据条数
        :param pager_count:  最多显示的页码个数
        """
        try:
            current_page = int(current_page)
        except Exception as e:
            current_page = 1

        if current_page < 1:
            current_page = 1

        self.current_page = current_page

        self.all_count = all_count
        self.per_page_num = per_page_num

        # 总页码
        all_pager, tmp = divmod(all_count, per_page_num)
        if tmp:
            all_pager += 1
        self.all_pager = all_pager

        self.pager_count = pager_count
        self.pager_count_half = int((pager_count - 1) / 2)

    @property
    def start(self):
        return (self.current_page - 1) * self.per_page_num

    @property
    def end(self):
        return self.current_page * self.per_page_num

    def page_html(self):
        # 如果总页码 < 11个：
        if self.all_pager <= self.pager_count:
            pager_start = 1
            pager_end = self.all_pager + 1
        # 总页码  > 11
        else:
            # 当前页如果<=页面上最多显示11/2个页码
            if self.current_page <= self.pager_count_half:
                pager_start = 1
                pager_end = self.pager_count + 1

            # 当前页大于5
            else:
                # 页码翻到最后
                if (self.current_page + self.pager_count_half) > self.all_pager:
                    pager_end = self.all_pager + 1
                    pager_start = self.all_pager - self.pager_count + 1
                else:
                    pager_start = self.current_page - self.pager_count_half
                    pager_end = self.current_page + self.pager_count_half + 1

        page_html_list = []
        # 添加前面的nav和ul标签
        page_html_list.append('''
                    <nav aria-label='Page navigation>'
                    <ul class='pagination'>
                ''')
        first_page = '<li><a href="?page=%s">首页</a></li>' % (1)
        page_html_list.append(first_page)

        if self.current_page <= 1:
            prev_page = '<li class="disabled"><a href="#">上一页</a></li>'
        else:
            prev_page = '<li><a href="?page=%s">上一页</a></li>' % (self.current_page - 1,)

        page_html_list.append(prev_page)

        for i in range(pager_start, pager_end):
            if i == self.current_page:
                temp = '<li class="active"><a href="?page=%s">%s</a></li>' % (i, i,)
            else:
                temp = '<li><a href="?page=%s">%s</a></li>' % (i, i,)
            page_html_list.append(temp)

        if self.current_page >= self.all_pager:
            next_page = '<li class="disabled"><a href="#">下一页</a></li>'
        else:
            next_page = '<li><a href="?page=%s">下一页</a></li>' % (self.current_page + 1,)
        page_html_list.append(next_page)

        last_page = '<li><a href="?page=%s">尾页</a></li>' % (self.all_pager,)
        page_html_list.append(last_page)
        # 尾部添加标签
        page_html_list.append('''
                                           </nav>
                                           </ul>
                                       ''')
        return ''.join(page_html_list)

后端模板：视图层 views.py

from utils.mypage import Pagination  # 导入模板
# 书籍的展示
def books(request):
    # 先查询出所有要展示的数据信息，
    book_queryset = models.Book.objects.all()
    current_page = request.GET.get('page',1) 
    all_count = book_queryset.count()
    # 传值生成对象
    page_obj = Pagination(current_page=current_page,all_count=all_count)
    # 直接对总数据进行切片操作
    page_queryset = book_queryset[page_obj.start:page_obj.end]
    # 将page_queryset传递到页面，替换之前的book_queryset
    return render(request,'books.html',locals())

前端只需要这一行代码就可以实现分页

<div class="text-center">{{ page_obj.page_html|safe }}</div>

前端示例：book_list.html

{% extends 'home.html' %}

{% block main %}
    <script>
        $('.index').removeClass('active')
        $('.books').addClass('active')
        $('.publish').removeClass('active')
        $('.author').removeClass('active')
    </script>
    <div>
        <div class="panel panel-primary">
            <div class="panel-heading">
                <h3 class="panel-title">图书管理</h3>
            </div>
            <div class="panel-body">
                <div>
                    <a href="/book_add/" class="btn btn-success pull-right">添加书籍</a>
                </div>
                <br>
                <br>

                <table class="table table-striped table-hover table-bordered">
                    <thead>
                    <tr>
                        <th>ID</th>
                        <th>书名</th>
                        <th>价格</th>
                        <th>出版日期</th>
                        <th>出版社</th>
                        <th>作者</th>
                        <th>操作</th>
                    </tr>
                    </thead>
                    <tbody>
                    {% for book in page_queryset %}
                        <tr>
                            <td>{{ book.id }}</td>
                            <td class="warning">{{ book.title }}</td>
                            <td class="info">{{ book.price }}</td>
                            <td class="dark">{{ book.publish_date|date:'Y-m-d' }}</td>
                            <td class="success">{{ book.publish.name }}</td>
                            <td>
                                {% for author in book.authors.all %}
                                    {% if forloop.last %}
                                        {{ author.name }}
                                    {% else %}
                                        {{ author.name }}、
                                    {% endif %}
                                {% endfor %}
                            </td>
                            <td>
                                <a href="{% url 'book_edit' book.pk %}" class="btn btn-primary btn-xs">编辑</a>
                                <a href="{% url 'book_delete' book.pk %}" class="btn btn-danger btn-xs">删除</a>
                                <button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal" id="bbb" onclick="AA('{{ html }}')">
  Launch
</button>
                            </td>
                        </tr>
                    {% endfor %}
                    </tbody>
                </table>
                {# 只需要这一行代码就可以实现分页 #}
              <div class="text-center">{{ page_obj.page_html|safe }}</div>
            </div>
        </div>
    </div>

{% endblock %}

posted @ 2022-03-02 22:12 hai起奈阅读(216) 评论(0) 编辑收藏举报

刷新页面返回顶部

Luz