Django组件——分页器(paginator)

一、视图层

from django.shortcuts import render

# Create your views here.

from .models import Book
from django.core.paginator import Paginator,EmptyPage


def index(request):
    """
    # 批量导入数据
    book_list=[]
    for i in range(100):
        book = Book.objects.create(title="book_%s" % i, price=i*i)
        book_list.append(book)
    Book.objects.bulk_create(book_list)
    """

    # 分页器的使用：
    book_list = Book.objects.all()

    paginator = Paginator(book_list, 8)   # 第二个参数设置每页显示的条数

    print(paginator.count)        # 数据总条数  100
    print(paginator.num_pages)    # 总页数  13
    print(paginator.page_range)   # 页码的列表 range(1, 14)


    page1 = paginator.page(1)  # 第一页的page对象
    # 显示某一页具体数据的两种方式：
    # 方式一：
    print("object_list", page1.object_list)  # object_list <QuerySet [<Book: Book object (1)>, <Book: Book object (2)>,...
    # 方式二:
    for i in page1:
        print(i)
    """输出
    Book object (1)
    Book object (2)
    Book object (3)
    Book object (4)
    Book object (5)
    Book object (6)
    Book object (7)
    Book object (8)
    """

    page2 = paginator.page(2)
    print(page2.has_next())         # 是否有下一页
    print(page2.next_page_number())   # 下一页的页码
    print(page2.has_previous())     # 是否有上一页
    print(page2.previous_page_number())  # 上一页的页码


    current_page_num = int(request.GET.get("page", 1))

    if paginator.num_pages > 11:
        if current_page_num-5 < 1:
            # 当前页码-5小于1时，默认显示前11个页码
            page_range = range(1, 12)
        elif current_page_num + 5 > paginator.num_pages:
            # 当前页码+5大于总页数时，默认显示后11个
            page_range = range(paginator.num_pages-10, paginator.num_pages+1)
        else:
            # 显示当前页码和左五右五共11个页码
            page_range = range(current_page_num-5, current_page_num+6)
    else:
        # 不超过11个页码的情况，显示所有页码
        page_range = paginator.page_range

    # 超出页码范围或小于1的页码，会抛出emptypage错误，做如下处理：
    try:
        current_page_num = int(request.GET.get("page", 1))  # /?page=1  get取不到默认给它默认值：1
        current_page = paginator.page(current_page_num)

        print("object_list", current_page.object_list)
        for i in current_page:
            print(i)
    except EmptyPage as e:
        current_page = paginator.page(1)  # 固定在出现emptypage时显示首页

    return render(request, "index.html", locals())

　　注意：

　　1、批量生成数据，添加到数组中，再一次性写入数据库表中：Book.objects.bulk_create(book_list)

　　2、分页器对象生成后，.count查看数据总条数，.num_pages显示总页数，.page_range页码列表。

　　3、显示某一页的具体数据有两种方式：

# 方式一：
print("object_list", page1.object_list)  # object_list <QuerySet [<Book: Book object (1)>, <Book: Book object (2)>,...
# 方式二:
for i in page1:
    print(i)
"""输出
Book object (1)
Book object (2)
Book object (3)
Book object (4)
Book object (5)
Book object (6)
Book object (7)
Book object (8)
"""

　　4、.page()方法可以生成页对象，具备如下方法可用于上一页下一页网页查看。

page2 = paginator.page(2)
print(page2.has_next())         # 是否有下一页
print(page2.next_page_number())   # 下一页的页码
print(page2.has_previous())     # 是否有上一页
print(page2.previous_page_number())  # 上一页的页码

　　5、得到当前页码，且设置默认页码为1；根据当前页码得到当前页对象。

current_page_num = int(request.GET.get("page", 1))  # /?page=1  get取不到默认给它默认值：1
current_page = paginator.page(current_page_num)

　　6、针对超出页码范围的页码，会抛出emptypage错误，可以做如下处理：

# 超出页码范围或小于1的页码，会抛出emptypage错误，做如下处理：
    try:
        current_page_num = int(request.GET.get("page", 1))  # /?page=1  get取不到默认给它默认值：1
        current_page = paginator.page(current_page_num)

        print("object_list", current_page.object_list)
        for i in current_page:
            print(i)
    except EmptyPage as e:
        current_page = paginator.page(1)  # 固定在出现emptypage时显示首页

　　7、页面具备翻页功能，设置同时最多只能显示11条，处理如下：

current_page_num = int(request.GET.get("page", 1))

if paginator.num_pages > 11:
    if current_page_num-5 < 1:
        # 当前页码-5小于1时，默认显示前11个页码
        page_range = range(1, 12)
    elif current_page_num + 5 > paginator.num_pages:
        # 当前页码+5大于总页数时，默认显示后11个
        page_range = range(paginator.num_pages-10, paginator.num_pages+1)
    else:
        # 显示当前页码和左五右五共11个页码
        page_range = range(current_page_num-5, current_page_num+6)
else:
    # 不超过11个页码的情况，显示所有页码
    page_range = paginator.page_range

二、模板层

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="/static/bootstrap-3.3.7/css/bootstrap.css">
</head>
<body>
<ul>
    {% for book in current_page %}
        <li>{{ book.title }}:{{ book.price }}</li>
    {% endfor %}
</ul>
<nav aria-label="Page navigation">
    <ul class="pagination">
{#        <li>#}
            {# 方法一：上一页在当前页码减1 #}
{#             <a href="?page={{ current_page_num|add:-1 }}" aria-label="Previous">#}
{#                 <span aria-hidden="true">上一页</span>#}
{#            </a>#}
{#        </li>#}
{#        方法二：#}
        {% if current_page.has_previous %}
            <li><a href="?page={{ current_page_num.previous_page_number }}" aria-label="Previous"><span aria-hidden="true">上一页</span></a></li>
        {% else %}
            {# 页码到第一页后，上一页设置为禁用 #}
            <li class="disabled"><a href="?page={{ current_page_num.previous_page_number }}" aria-label="Previous"><span aria-hidden="true">上一页</span></a></li>
        {% endif %}

        {# 自动生成<li>标签，路径前面不变得情况下从?开始配置即可 #}
        {% for item in page_range %}
            {# 当前页面添加active显示高亮 #}
            {% if current_page_num == item %}
                <li class="active"><a href="?page={{ item }}">{{ item }}</a></li>
            {% else %}
                <li><a href="?page={{ item }}">{{ item }}</a></li>
            {% endif %}
        {% endfor %}

        {% if current_page.has_next %}
            <li><a href="?page={{ current_page_num.next_page_number }}" aria-label="Next"><span aria-hidden="true">下一页</span></a></li>
        {% else %}
            <li class="disabled"><a href="?page={{ current_page_num.next_page_number }}" aria-label="Next"><span aria-hidden="true">下一页</span></a></li>
        {% endif %}
    </ul>
</nav>

</body>
</html>

注意：

　　1、读取当前页码数据生成标签展示在页面上：

<ul>
    {% for book in current_page %}
        <li>{{ book.title }}:{{ book.price }}</li>
    {% endfor %}
</ul>

　　2、引入bootstrap

<head>
    <link rel="stylesheet" href="/static/bootstrap-3.3.7/css/bootstrap.css">
</head>

body部分：
<nav aria-label="Page navigation">
    <ul class="pagination">
    ...
    </ul>
</nav>

　　3、生成页面页码标签，路径前面不变的情况下可以从?开始配置：

{# 自动生成<li>标签，路径前面不变得情况下从?开始配置即可 #}
{% for item in page_range %}
    {# 当前页面添加active显示高亮 #}
    {% if current_page_num == item %}
        <li class="active"><a href="?page={{ item }}">{{ item }}</a></li>
    {% else %}
        <li><a href="?page={{ item }}">{{ item }}</a></li>
    {% endif %}
{% endfor %}

　　4、生成页面翻页，上一页、下一页：

　　（1）第一种方式是在当前页码做加减法：{{ current_page_num|add:-1 }}；{{ current_page_num|add:1 }}

<li>
    <!--方法一：上一页在当前页码减1 -->
    <a href="?page={{ current_page_num|add:-1 }}" aria-label="Previous">
        <span aria-hidden="true">上一页</span>
    </a>
</li>

　　（2）第二种方式是使用page对象自带的方法：

<!--上一页-->
{% if current_page.has_previous %}
    <li><a href="?page={{ current_page_num.previous_page_number }}" aria-label="Previous"><span aria-hidden="true">上一页</span></a></li>
{% else %}
    {# 页码到第一页后，上一页设置为禁用 #}
    <li class="disabled"><a href="?page={{ current_page_num.previous_page_number }}" aria-label="Previous"><span aria-hidden="true">上一页</span></a></li>
{% endif %}


<!--下一页-->
{% if current_page.has_next %}
    <li><a href="?page={{ current_page_num.next_page_number }}" aria-label="Next"><span aria-hidden="true">下一页</span></a></li>
{% else %}
    <li class="disabled"><a href="?page={{ current_page_num.next_page_number }}" aria-label="Next"><span aria-hidden="true">下一页</span></a></li>
{% endif %}