分页类的封装

"""
如果想要以后使用分页，需要以下两个步骤：
在视图函数：
def customer_list(request):
    # 这里是获取搜索form表单提交的搜索关键字
    keyword = request.GET.get('keyword','').strip()
    # 使用Q对象进行或查询
    con = Q()
    if keyword:
        con.connector = 'OR'
        con.children.append(('username__contains', keyword))
        con.children.append(('mobile__contains', keyword))
        con.children.append(('level__title__contains', keyword))
    # 查询数据库,多了一个>filter是进行搜索查询
    queryset = models.Customer.objects.filter(con).filter(active=1).select_related('level')
    # 分页数据展示,引入这个定义好的类就行,传入request和查询出来的queryset
    pager = Pagination(request, queryset)
    # 返回给前端页面的数据，直接locals()即可
    return render(request,'customer_list.html',locals())

在页面上：
    展示数据
    {% for row in pager.queryset %}
        {{row.id}}
    {% endfor %}

    在数据下面添加分页,这个样式pagination是借用的bootstrap3的css样式
    <ul class="pagination">
        {{ pager.html }}
    </ul>
"""
import copy
from django.utils.safestring import mark_safe


class Pagination(object):
    """ 分页 """

    def __init__(self, request, query_set, per_page_count=10):

        self.query_dict = copy.deepcopy(request.GET)
        self.query_dict._mutable = True

        self.query_set = query_set
        total_count = query_set.count()
        self.total_count = total_count
        # 计算出总共有多少页面
        self.total_page, div = divmod(total_count, per_page_count)
        if div:
            self.total_page += 1

        page = request.GET.get('page')
        if not page:
            page = 1
        else:
            if not page.isdecimal():
                page = 1
            else:
                page = int(page)
                if page <= 0:
                    page = 1
                else:
                    if page > self.total_page:
                        page = self.total_page

        self.page = page
        self.per_page_count = per_page_count

        self.start = (page - 1) * per_page_count
        self.end = page * per_page_count

    def html(self):
        pager_list = []
        if not self.total_page:
            return ""

        # 总页码小于11
        if self.total_page <= 11:
            start_page = 1
            end_page = self.total_page
        else:
            # 总页码比较多
            # 判断当前页 <=6: 1~11
            if self.page <= 6:
                start_page = 1
                end_page = 11
            else:
                if (self.page + 5) > self.total_page:
                    start_page = self.total_page - 10
                    end_page = self.total_page
                else:
                    start_page = self.page - 5
                    end_page = self.page + 5

        self.query_dict.setlist('page', [1])
        pager_list.append('<li><a href="?{}">首页</a></li>'.format(self.query_dict.urlencode()))

        if self.page > 1:
            self.query_dict.setlist('page', [self.page - 1])
            pager_list.append('<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode()))

        for i in range(start_page, end_page + 1):
            self.query_dict.setlist('page', [i])
            if i == self.page:
                item = '<li class="active"><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            else:
                item = '<li><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            pager_list.append(item)

        if self.page < self.total_page:
            self.query_dict.setlist('page', [self.page + 1])
            pager_list.append('<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode()))

        self.query_dict.setlist('page', [self.total_page])
        pager_list.append('<li><a href="?{}">尾页</a></li>'.format(self.query_dict.urlencode()))

        pager_list.append('<li class="disabled"><a>数据{}条{}页</a></li>'.format(self.total_count, self.total_page))
        pager_string = mark_safe("".join(pager_list))
        return pager_string

    def queryset(self):
        if self.total_count:
            return self.query_set[self.start:self.end]
        return self.query_set