web-分页

pager模块：

class Pagination(object):
    def __init__(self,current_pag,page_total,per_item_page=30,max_page_number=11):

        # 当前页

        try:
            v = int(current_pag)
            if v <= 0:
                v = 1
            self.current_pag = v
        except Exception as e:
            self.current_pag = 1

        #全部数据
        self.page_total = page_total

        # 每页显示30条数据
        self.per_item_page = per_item_page

        #显示11个页码
        self.max_page_number = max_page_number

    @property
    def start(self):
        return (self.current_pag - 1) * self.per_item_page  #切片开始位置使用当前页-1  *  每页要显示的数据数量

    @property
    def end(self):
        return (self.current_pag) * self.per_item_page      #切片结束位置使用当前页  * 每页要显示的数据数量

    @property
    def num_pages(self):
        a,b = divmod(self.page_total,self.per_item_page)    #所有数据显示的页码数量使用 divmod函数总数据数取余每页显示的数据数如果余数小数部分为0则返回a，否则返回a + 1

        if b == 0:
            return a
        return a + 1

    def page_number(self):

        if self.num_pages < self.max_page_number:
            return range(1,self.num_pages + 1)

        median = self.max_page_number // 2

        if self.current_pag <= median:
            return range(1,self.max_page_number + 1)

        if self.current_pag > median:
            if (self.current_pag + median) > self.num_pages:
                return range(self.num_pages - self.max_page_number,self.num_pages + 1)
            return range(self.current_pag - median,self.current_pag + median + 1)

    def page_number_str(self):
        page_list = []
        if self.current_pag == 1:
            prev_page = '<a href="#" style="display: none"></a>'
        else:
            prev_page = '<a href="/index.html?p=%s">上一页</a>' % (self.current_pag - 1)
        page_list.append(prev_page)

        for i in self.page_number():
            temp = '<a href="/index.html?p=%s">%s</a>'% (i,i)
            page_list.append(temp)

        next_page = '<a href="/index.html?p=%s">下一页</a>' % (self.current_pag + 1)
        page_list.append(next_page)

        return ''.join(page_list)