自定义分页

1 . 分页的实现与使用 

app01  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
        # 当前访问页的数字
        self.current_page_num = current_page_num
        # 数据总条数
        self.all_count = all_count
        # 每页显示的数据条数
        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

        # 最多显示的页码个数,(比如默认显示11个页码,当前页码11-1 / 2  就是第五页)
        self.pager_count = pager_count
        self.pager_count_half = int((pager_count - 1) / 2)  # 5
                                        #左5页右5页



        # print(request.GET)
        # <QueryDict:{'a':['1'],'b':['2'],'xxx':[123]}>    搜索条件


        # 保存搜索条件
        import copy
        # 深度拷贝
        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：(比如10页,那么就显示10页)
        if self.all_pager <= self.pager_count:
            pager_start = 1
            pager_end = self.all_pager + 1    #<11页,就显示总页数,+1是因为ranger循环的时候顾头不顾尾
        # 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    #倒数11个

                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 = []
        # {source:[2,], status:[2], gender:[2],consultant:[1],page:[1]}
        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"}
        # 中间页码
        for i in range(pager_start, pager_end):

            self.params["page"]=i

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


        #     尾页
        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)

 

views.py

from django.shortcuts import render

# Create your views here.


from app01.models import Book
from django.core.paginator import Paginator,EmptyPage
def index(request):

    '''

    批量插入数据：
        # for i in range(100):
        #     Book.objects.create(title="book_%s"%i,price=i*i)


        book_list=[]

        for i in range(100):
            book=Book(title="book_%s"%i,price=i*i)
            book_list.append(book)

        Book.objects.bulk_create(book_list)



    分页器的使用：
                paginator=Paginator(book_list,8)

                print(paginator.count) # 100
                print(paginator.num_pages) # 分页数：13
                print(paginator.page_range) # range(1, 14)

                page=paginator.page(5)
                for i in page:
                    print(i)

                print(page.has_next())
                print(page.has_previous())
                print(page.next_page_number())
                print(page.previous_page_number())



                    book_list = Book.objects.all()
                    paginator = Paginator(book_list, 2)
                    try:

                        current_page_num=request.GET.get("page",1)
                        current_page=paginator.page(current_page_num)
                    except EmptyPage as e:
                        current_page_num=1
                        current_page = paginator.page(1)

    '''
    # 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())

 

2 . 编辑后保留原URL搜索的条件

　　① . request.GET 是一个QueryDict 类型的,想要取出 ? 后面的结构用 request.GET.unlencode() 

　　② . request.GET 默认是不可修改的,需要把 params=QueryDict(mutable=True),mutable这个参数设置成 True . 

　　③ . 1和2虽然可以更改,但是这样会麻烦,因为QueryDict 是保存的用户请求状态,当我们完成这次请求之后,下次请求会乱,所有我们不用...我们可以使用copy

import copy 

self.params=copy.deepcopy(request.GET)

#由于 print(request.GET) 的结果 <QueryDict:{'a':['1'],'b':['2'],'xxx':[123]}> ,只能读取,不能更改
#所所以我们要先深度拷贝一份,虽然是深度拷贝,但是在源码里面,request.GET 的 mutable=False----不能更改,但是拷贝之后的mutable=True----可以更改

self.params.urlencode() ---#可以将{"a":"1","b":"2"} ===>a=1&b=2&xxx=123 

 

 效果 :