Django -- 自定义分页,保存搜索条件

预备知识:

request.GET 我们得到的是一个QueryDict,然而这个QueryDict是不能改变的,只能看,如果我们想要改变的话,需要使用copy模块的copy.deepcopy,进行深拷贝

自己写一个page.py文件,把类写好

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)  #判断访问页是否一个数字
        except Exception as e:  #如果访问页不是数字,就默认访问页为第一页
            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

        # 总数据/每页要显示的数据条数,得到一个元组
        all_pager, tmp = divmod(all_count, per_page_num)#divmod返回一个元组,包含除法的结果和余数
        if tmp: #如果有余数的话,总页数要+1
            all_pager += 1
        self.all_pager = all_pager


        self.pager_count = pager_count
        self.pager_count_half = int((pager_count - 1) / 2)  # 实现左五右五的效果


        # 保存搜索条件

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

    @property
    def start(self): #将start设为静态方法
        return (self.current_page_num - 1) * self.per_page_num

    @property
    def end(self):#将end设为静态方法
        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  #开始页码是第一页
            pager_end = self.all_pager + 1 #结束页码是最后一页,+1是因为range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

                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"}
        #保存访问记录
        for i in range(pager_start, pager_end):

            self.params["page"]=i

            if i == self.current_page_num:  #urlencode()可以再把修改后的querydict组包变成a=1&b=2的形式
                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)


        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)

视图部分:

def index(request):
    # 自定义分页

    print(request.GET)


    from app01.page import Pagination   #引入自己写的类
    current_page_num = request.GET.get("page")  #获取当前页
    book_list = Book.objects.all()  #所有书籍的列表
    pagination=Pagination(current_page_num,book_list.count(),request) #实例化对象,把当前页,数据的总条数传给对象
    '''
    
    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] #这个地方的book_list指的是每一页显示的书籍

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