scrapy-splash如何处理无限滚动？

Question

我想通过向下滚动网页生成的内容反向工程。问题出在url https://www.crowdfunder.com/user/following_page/80159?user_id=80159&limit=0&per_page=20&screwrand=933中。screwrand似乎不遵循任何模式，所以反向urls不起作用。我正在考虑使用Splash进行自动渲染。如何使用Splash来像浏览器一样滚动？非常感谢!以下是两个请求的代码：

request1 = scrapy_splash.SplashRequest(
    'https://www.crowdfunder.com/user/following/{}'.format(user_id),
     self.parse_follow_relationship,
     args={'wait':2},
     meta={'user_id':user_id, 'action':'following'},
     endpoint='http://192.168.99.100:8050/render.html')

yield request1

request2 = scrapy_splash.SplashRequest(
    'https://www.crowdfunder.com/user/following_user/80159?user_id=80159&limit=0&per_page=20&screwrand=76',
    self.parse_tmp,
    meta={'user_id':user_id, 'action':'following'},
    endpoint='http://192.168.99.100:8050/render.html')

yield request2

ajax request shown in browser console

Answer 1

要滚动页面，您可以编写一个自定义呈现脚本(请参阅http://splash.readthedocs.io/en/stable/scripting-tutorial.html)，如下所示：

function main(splash)
    local num_scrolls = 10
    local scroll_delay = 1.0

    local scroll_to = splash:jsfunc("window.scrollTo")
    local get_body_height = splash:jsfunc(
        "function() {return document.body.scrollHeight;}"
    )
    assert(splash:go(splash.args.url))
    splash:wait(splash.args.wait)

    for _ = 1, num_scrolls do
        scroll_to(0, get_body_height())
        splash:wait(scroll_delay)
    end        
    return splash:html()
end

要呈现此脚本，请使用'execute‘端点，而不是render.html端点：

script = """<Lua script> """
scrapy_splash.SplashRequest(url, self.parse,
                            endpoint='execute', 
                            args={'wait':2, 'lua_source': script}, ...)

Answer 2

谢谢Mikhail，我试过你的滚动脚本，它工作了，但我也注意到你的脚本滚动太多一次，一些js没有时间渲染而被跳过，所以我做了一些小的修改，如下所示：

function main(splash)
        local num_scrolls = 10
        local scroll_delay = 1

        local scroll_to = splash:jsfunc("window.scrollTo")
        local get_body_height = splash:jsfunc(
            "function() {return document.body.scrollHeight;}"
        )
        assert(splash:go(splash.args.url))
        splash:wait(splash.args.wait)

        for _ = 1, num_scrolls do
            local height = get_body_height()
            for i = 1, 10 do
                scroll_to(0, height * i/10)
                splash:wait(scroll_delay/10)
            end
        end        
        return splash:html()
end