Django中的自定义分页和CBV

一.Django的分页器  

view

from django.shortcuts import render,HttpResponse

# Create your views here.
from app01.models import *
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger

def index(request):

    '''
    批量导入数据:

    Booklist=[]
    for i in range(100):
        Booklist.append(Book(title="book"+str(i),price=30+i*i))
    Book.objects.bulk_create(Booklist)

分页器的使用:

    book_list=Book.objects.all()

    paginator = Paginator(book_list, 10)

    print("count:",paginator.count)           #数据总数
    print("num_pages",paginator.num_pages)    #总页数
    print("page_range",paginator.page_range)  #页码的列表



    page1=paginator.page(1) #第1页的page对象
    for i in page1:         #遍历第1页的所有数据对象
        print(i)

    print(page1.object_list) #第1页的所有数据


    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

    # 抛错
    #page=paginator.page(12)   # error:EmptyPage

    #page=paginator.page("z")   # error:PageNotAnInteger

    '''


    book_list=Book.objects.all()

    paginator = Paginator(book_list, 10)
    page = request.GET.get('page',1)
    currentPage=int(page)

    try:
        print(page)
        book_list = paginator.page(page)
    except PageNotAnInteger:
        book_list = paginator.page(1)
    except EmptyPage:
        book_list = paginator.page(paginator.num_pages)
　　
# 自定义分页

　　print(request.GET)


　　from app01.page import Pagination
　　current_page_num = request.GET.get("page")
　　book_list = Book.objects.all()
　　pagination=Pagination(current_page_num,book_list.count(),request)
　　'''

　　count=100
　　per_page=9

　　current_page_num=1 start 0 end 8
　　current_page_num=2 start 8 end 16
　　current_page_num=3 start 16 end 24 
　　current_page_num=n start (n-1)*per_page end n*per_page

　　'''
　　book_list=book_list[pagination.start:pagination.end]

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

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" 
    integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>
<body>

<div class="container">

    <h4>分页器</h4>
    <ul>

        {% for book in book_list %}
             <li>{{ book.title }} -----{{ book.price }}</li>
        {% endfor %}

     </ul>


    <ul class="pagination" id="pager">

                 {% if book_list.has_previous %}
                    <li class="previous"><a href="/index/?page={{ book_list.previous_page_number }}">上一页</a></li>
                 {% else %}
                    <li class="previous disabled"><a href="#">上一页</a></li>
                 {% endif %}


                 {% for num in paginator.page_range %}

                     {% if num == currentPage %}
                       <li class="item active"><a href="/index/?page={{ num }}">{{ num }}</a></li>
                     {% else %}
                       <li class="item"><a href="/index/?page={{ num }}">{{ num }}</a></li>

                     {% endif %}
                 {% endfor %}



                 {% if book_list.has_next %}
                    <li class="next"><a href="/index/?page={{ book_list.next_page_number }}">下一页</a></li>
                 {% else %}
                    <li class="next disabled"><a href="#">下一页</a></li>
                 {% endif %}

            </ul>
</div>



</body>
</html>

扩展

def index(request):


    book_list=Book.objects.all()

    paginator = Paginator(book_list, 15)
    page = request.GET.get('page',1)
    currentPage=int(page)

    #  如果页数十分多时，换另外一种显示方式
    if paginator.num_pages>30:

        if currentPage-5<1:
            pageRange=range(1,11)
        elif currentPage+5>paginator.num_pages:
            pageRange=range(currentPage-5,paginator.num_pages+1)

        else:
            pageRange=range(currentPage-5,currentPage+5)

    else:
        pageRange=paginator.page_range


    try:
        print(page)
        book_list = paginator.page(page)
    except PageNotAnInteger:
        book_list = paginator.page(1)
    except EmptyPage:
        book_list = paginator.page(paginator.num_pages)


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

自定义分页(app01中的page.py)

"""
分页组件使用示例：

    obj = Pagination(request.GET.get('page',1),len(USER_LIST),request.path_info)
    page_user_list = USER_LIST[obj.start:obj.end]
    page_html = obj.page_html()

    return render(request,'index.html',{'users':page_user_list,'page_html':page_html})




"""

class Pagination(object):

    def __init__(self,current_page_num,all_count,request,per_page_num=2,pager_count=11):
        """
        封装分页相关数据
        :param current_page_num: 当前访问页的数字
        :param all_count:    分页数据中的数据总条数
        :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_num = int(current_page_num)
        except Exception as e:
            current_page_num = 1

        if current_page_num <1:
            current_page_num = 1

        self.current_page_num = current_page_num

        self.all_count = all_count
        self.per_page_num = per_page_num

        # 实际总页码
        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)  # 5


        # 保存搜索条件

        import copy
        self.params=copy.deepcopy(request.GET) # {"a":"1","b":"2"}

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

    @property
    def end(self):
        return self.current_page_num * 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_num <= 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_num + self.pager_count_half) > self.all_pager:

                    pager_start = self.all_pager - self.pager_count + 1
                    pager_end = self.all_pager + 1

                else:
                    pager_start = self.current_page_num - self.pager_count_half
                    pager_end = self.current_page_num + self.pager_count_half + 1

        page_html_list = []

        first_page = '<li><a href="?page=%s">首页</a></li>' % (1,)
        page_html_list.append(first_page)

        if self.current_page_num <= 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_num - 1,)

        page_html_list.append(prev_page)


        #self.params=copy.deepcopy(request.GET) # {"a":"1","b":"2"}

        for i in range(pager_start, pager_end):

            self.params["page"]=i

            if i == self.current_page_num:
                                        # 保存搜索条件
                temp = '<li class="active"><a href="?%s">%s</a></li>' %(self.params.urlencode(),i)
            else:
                                        # 保存搜索条件
                temp = '<li><a href="?%s">%s</a></li>' % (self.params.urlencode(),i,)
            page_html_list.append(temp)


        if self.current_page_num >= 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_num + 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)

        return ''.join(page_html_list)

index.html

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- 最新版本的 Bootstrap 核心 CSS 文件 -->
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>
<body>

<ul>
    {% for book in book_list %}
    <li>{{ book.title }} ---- {{ book.price }}</li>
    {% endfor %}
</ul>

<nav aria-label="Page navigation">
  <ul class="pagination">
   {{ pagination.page_html|safe }}
  </ul>
</nav>


</body>
</html>

二.CBV

1.FBV

　　FBV（function base views） 就是在视图里使用函数处理请求。

2.CBV

　　CBV（class base views） 就是在视图里使用类处理请求。

优点：

  1. 提高了代码的复用性，可以使用面向对象的技术，比如Mixin（多继承）
  2. 可以用不同的函数针对不同的HTTP方法处理，而不是通过很多if判断，提高代码可读性

FBV

看代码：

urls.py

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from django.conf.urls import url, include
# from django.contrib import admin
from mytest import views
 
urlpatterns = [
    # url(r‘^admin/‘, admin.site.urls),
    url(r‘^index/‘, views.index),
]

views.py

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from django.shortcuts import render
 
 
def index(req):
    if req.method == ‘POST‘:
        print(‘method is :‘ + req.method)
    elif req.method == ‘GET‘:
        print(‘method is :‘ + req.method)
    return render(req, ‘index.html‘)

注意此处定义的是函数【def index(req):】

index.html

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>index</title>
</head>
<body>
    <form action="" method="post">
        <input type="text" name="A" />
        <input type="submit" name="b" value="提交" />
    </form>
</body>
</html>

上面就是FBV的使用。

CBV

将上述代码中的urls.py 修改为如下：

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from mytest import views
 
urlpatterns = [
    # url(r‘^index/‘, views.index),
    url(r‘^index/‘, views.Index.as_view()),
]

注：url(r‘^index/‘, views.Index.as_view()),  是固定用法。

Django的url是将一个请求分配给可调用的函数的，而不是一个class。针对这个问题，class-based view提供了一个as_view()静态方法（也就是类方法），调用这个方法，会创建一个类的实例，然后通过实例调用dispatch()方法，dispatch()方法会根据request的method的不同调用相应的方法来处理request（如get() , post()等）。

将上述代码中的views.py 修改为如下：

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from django.views import View
 
 
class Index(View):
    def get(self, req):
        print(‘method is :‘ + req.method)
        return render(req, ‘index.html‘)
 
    def post(self, req):
        print(‘method is :‘ + req.method)
        return render(req, ‘index.html‘)

注：类要继承 View ，类中函数名必须小写。

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原文地址：https://www.cnblogs.com/chenxi67/p/9924003.html