如何使用 cursor() 进行分页? [英] How to use cursor() for pagination?

问题描述

谁能给我指出 cursor() 的实际应用来进行分页?

我不清楚如何使用文档.

这是我的查询:

items = db.GqlQuery("SELECT * FROM Item ORDER BY date DESC LIMIT 30")

我是这样渲染的:

self.response.out.write("
")对于项目中的项目:self.response.out.write("""<li><a href="/vote/%s?type=%s"> ^ </a><a href="%s">;%s</a> <span id='Small'>(%s)</span><br/><div id='小'>%s 点 %s %s </a>|<a href="/item/%s#disqus_thread"></a></div></li><br/>""" %(str(item.key().id()),商品类型, item.url, item.title, urlparse(item.url).netloc,item.points, item.date.strftime("%B %d, %Y %I:%M%p"), item.user_who_liked_this_item, str(item.key().id()), str(item.key().ID())))self.response.out.write("</ol>")

谢谢！

更新

阿米尔:感谢您的回答，但我无法使此链接正常工作.这是我所拥有的:

#============在此处添加光标============#cursor = self.request.get("cursor")如果游标:query.with_cursor(cursor)项目 = query.fetch(30)游标 = query.cursor()#============在此处添加光标============##============正常输出============#self.response.out.write("
")对于项目中的项目:self.response.out.write("""
<a href="/vote/%s?type=%s">^ </a><a href="%s"><span id="large">%s</span></a><span id='小'>(%s)</span><br/>%s
<span id='小'>%s 点 %s %s </a>|<a href="/item/%s#disqus_thread"></a></span></li><br/>""" %(str(item.key().id())，商品类型，item.url，item.title, urlparse(item.url).netloc,item.summary, item.points, item.date.strftime("%B %d, %Y %I:%M%p"),item.user_who_liked_this_item, str(item.key().id()),str(item.key().id())))self.response.out.write("</ol>")#============正常输出============##============链接到光标============#self.response.out.write("""

但这会导致此网址不显示任何内容:

 <代码>的http://本地主机:?8083/目录类型=最新光标= E9oBdgoTc2FyYWgtZm9yLXByZXNpZGVudBoESXRlbUtSBGRhdGVYAkwhQ1VSU09SIWoiahNzYXJhaC1mb3ItcHJlc2lkZW50cgsLEgRJdGVtGKsCDHIVCAcaBGRhdGUgACoJCMid8OXW4qYCggELCxIESXRlbRirAgzgAQAU

更新 2

请参阅下面的@Amir 评论:将第二个 ? 更改为 & 解决了问题.谢谢！

解决方案

这是一个让您入门的简单示例...

query = db.GqlQuery("SELECT * FROM Item ORDER BY date DESC")cursor = self.request.get('cursor')如果游标:query.with_cursor(cursor)项目 = query.fetch(30)游标 = query.cursor()...您的常规输出...self.response.out.write('<a href="yoururl?cursor=%s">下一页</a>' % cursor)

Can anyone point me to a practical application of cursor() to do pagination?

I am not clear how to use cursor() as given in the documentation.

This is my query:

items = db.GqlQuery("SELECT * FROM Item ORDER BY date DESC LIMIT 30")

which I render like this:

self.response.out.write("<ol>")
for item in items:
    self.response.out.write("""<li><a href="/vote/%s?type=%s"> ^ </a><a href="%s">%s</a> <span id='Small'>(%s)</span><br /> 
        <div id='Small'> 
        %s points %s by %s <a href="/item/%s"></a> | 
        <a href="/item/%s#disqus_thread"></a></div>
        </li><br /> """ % 
        (str(item.key().id()), merchandise_type, item.url, item.title, urlparse(item.url).netloc,
        item.points, item.date.strftime("%B %d, %Y %I:%M%p"), item.user_who_liked_this_item, str(item.key().id()), str(item.key().id())))                               

   self.response.out.write("</ol>")

Thanks!

UPDATE

Hi Amir: Thanks for your answer but I could't make this link work. Here's what I have:

#===========adding cursor here===========#
            cursor = self.request.get("cursor")
            if cursor: query.with_cursor(cursor)
            items = query.fetch(30)
            cursor  = query.cursor()

#===========adding cursor here===========#

#===========regular output===========#
            self.response.out.write("<ol>")
            for item in items:
                self.response.out.write("""<li>
                <a href="/vote/%s?type=%s"> ^ </a><a href="%s">
                <span id="large">%s</span></a> 
                <span id='Small'>(%s)</span>
                <br />  
                %s<br /> <span id='Small'> 
                %s points %s by %s <a href="/item/%s"></a> | 
                <a href="/item/%s#disqus_thread"></a>
                </span>
                </li><br /> """ %           
                (str(item.key().id()), merchandise_type, item.url, 
                item.title, urlparse(item.url).netloc, 
                item.summary, item.points, item.date.strftime("%B %d, %Y %I:%M%p"), 
                item.user_who_liked_this_item, str(item.key().id()),  
                str(item.key().id())))                               

            self.response.out.write("</ol>")
#===========regular output===========#

#===========link to cursor===========#
            self.response.out.write("""<a href="/dir?type=%s?cursor=%s">Next
            Page</a>""" % (merchandise_type, cursor))

But this results in this url which displays nothing:

http://localhost:8083/dir?type=newest?cursor=E9oBdgoTc2FyYWgtZm9yLXByZXNpZGVudBoESXRlbUtSBGRhdGVYAkwhQ1VSU09SIWoiahNzYXJhaC1mb3ItcHJlc2lkZW50cgsLEgRJdGVtGKsCDHIVCAcaBGRhdGUgACoJCMid8OXW4qYCggELCxIESXRlbRirAgzgAQAU

Update 2

See @Amir comment below: changing the second ? to & solved the problem. Thanks!

解决方案

Here's a simple example to get you started...

query = db.GqlQuery("SELECT * FROM Item ORDER BY date DESC")
cursor = self.request.get('cursor')
if cursor: query.with_cursor(cursor)
items = query.fetch(30)
cursor = query.cursor()

... your regular output ...

self.response.out.write('<a href="yoururl?cursor=%s">Next Page</a>' % cursor)

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