django分页器的一些思考

Posted 2021-01-12 rongze-blog

今天用django写了两个分页器，实现的思路并不一样，发现二者各有利弊

 

第一种方法：从数据库获取数据，在后端用字符串格式化的方法做成html语句，然后传到前端进行渲染

代码如下

views

username = req.session[‘username‘]

        currunt_page=req.GET.get("page", 1)
        currunt_page=int(currunt_page)
        end_page=currunt_page*10
        start_page=end_page-10

        class_list = models.Class.objects.all()[start_page:end_page]
        total_count=models.Class.objects.all().count()
        page_num, odd=divmod(total_count, 10) 

        page_list=[]

        if odd != 0:
            page_num+=1

        if currunt_page <= 5:
            page_start = 1
            page_end = 11
        elif currunt_page >= page_num - 5 and currunt_page<=page_num:
            page_start = page_num - 10
            page_end = page_num
        else:
            page_start = currunt_page - 5
            page_end = currunt_page + 5

        if currunt_page==1:
            page_list.append("<a href=‘/class_manage.html?page=%s‘>上一页</a>" % (currunt_page))
        else:
            page_list.append("<a href=‘/class_manage.html?page=%s‘>上一页</a>" % (currunt_page-1))

        for i in range(page_start, page_end+1):
            if i == currunt_page:
                page_list.append("<a class=‘active‘ href=‘/class_manage.html?page=%s‘>%s</a>"%(i,i,))
            else:
                page_list.append("<a href=‘/class_manage.html?page=%s‘>%s</a>"%(i,i,))

        if currunt_page==page_num:
            page_list.append("<a href=‘/class_manage.html?page=%s‘>下一页</a>" % (currunt_page))
        else:page_list.append("<a href=‘/class_manage.html?page=%s‘>下一页</a>" % (currunt_page+1))
        pager="".join(page_list)

        return render(req, ‘class_manage.html‘, {‘username‘: username,"class_list":class_list,"page_list":pager})

html

<div class="page">
            {{ page_list|safe }}
</div>

 

 

 

第二种方法：在后端生成数据包传到前端，使用for循环进行渲染（传输数据时，假设current_page和page_list已构造成一个字典）

user = request.session.get("user")
    cla_list = models.Class.objects.all()

    count = cla_list.count()
    current_page = request.GET.get("page", 1)
    current_page=int(current_page)
    opt= request.GET.get("opt",None)
    page_num, last = divmod(count, 10)

    page_list = []

    if last!=0:
        page_num += 1

    if current_page != 1 and current_page != page_num:
        if opt == "‘next‘":
            current_page+=1
        elif opt == "‘last‘":
            current_page-=1
    if current_page == 1 and opt == "‘next‘":
        current_page += 1
    elif current_page == page_num and opt == "‘last‘":
        current_page -= 1

    if current_page<=5:
        for i in range(1, 11):
            page_list.append(i)
    elif current_page>=page_num-5:
        for i in range(page_num-10, page_num+1):
            page_list.append(i)
    else:
        for i in range(current_page-5, current_page+6):
            page_list.append(i)

    cla_list_send = []

    for item in cla_list[(current_page-1)*10:current_page*10]:
        cla_list_send.append(item)

    return render(request,"classes.html",{"user":user, "cla_list":cla_list_send,"page_list":page_list,"current_page":current_page})

html

<a href="/cla_manage?page={{ current_page }};opt=‘last‘">上一页</a>
<span>
{% for i in page_list %}
    <a href="/cla_manage?page={{ i }}">{{ i }}</a>
{% endfor %}
</span>
<a href="/cla_manage?page={{ current_page }};opt=‘next‘">下一页</a>

 

 

 

由于这里只对两种思路进行探讨，所以只选取了部分代码，所以希望看到这篇文章的人不必过于关注代码细节

 

下面讨论两种方式的利弊：

1. 从复杂度来说：这两种方式在算法复杂度上相差不大（这里要注意django在前端代码中写的for循环语句，本质还是在后端先进行了迭代，然后django会自己生成html代码然后发送到前端）

2. 从封装调用来说：如果在后端将二者进行封装，在接口方面而这需要传入的参数相差不大，但是在调用时明显第二种不够友好，因为对于前端来说要调用许多数据

3. 从亲后端分离来说：第二种做到了前后端分离，而第一种需要在后端写html代码

 

自己更倾向于第一种，当然分页器第一次接触，还未进行更加深入的思考，这篇文章来日还要再进行总结。