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如何使用Apify和Puppeteer构建成功的网页抓取结果?

apify puppeteer web-scraping html javascript

NoUsername9 · 技术社区 · 6 年前

使用Apify和Puppeteer,我想抓取以下URL的数据表:

https://en.wikipedia.org/wiki/List_of_hedge_funds

我希望结果是一个对象数组。数组的每个元素都应该代表 <tr> 原始数据源表的行,并且是一个具有以下属性的JS对象。

{ firmName, firmUrl, hq, hqUrl, aum, }

哪里:

firmName 是 .innerText() 第一个 <td> 每行的元素。
firmUrl 是 href 第一个属性 <td> 每行的元素。
hq 是 . innerText() 第二个 <td> 每行的元素。
hqUrl 是 href 第二个属性 <td> 每行的元素。
aum 是 .interText() 第三 <td> 每行的元素。

具体来说,例如,我希望看到以下对象返回给我。

我想看到的,备选方案A:

[{
  "url": "https://en.wikipedia.org/wiki/List_of_hedge_funds",
  "pageTitle": "List of hedge funds - Wikipedia",
  "links": [
    {
      firmName: "Bridgewater Associates",
      firmUrl: "/wiki/Bridgewater_Associates",
      hq: "Westport, Connecticut",
      hqUrl: "/wiki/Westport,_Connecticut",
      aum: "$132,050",
    }
    // ...x39 more times
  ]
}]

或者,对象可以如下(我不知道哪种是可能的,这是我困惑的一部分)

我想看到的,备选方案B:

[
  {
    "url": "https://en.wikipedia.org/wiki/List_of_hedge_funds",
    "pageTitle": "List of hedge funds - Wikipedia",
    "links": {
      firmName: "Bridgewater Associates",
      firmUrl: "/wiki/Bridgewater_Associates",
      hq: "Westport, Connecticut",
      hqUrl: "/wiki/Westport,_Connecticut",
      aum: "$132,050",
    },  
  },
  // ...x39 more times
]

但实际上,我看到了以下结果。

我实际看到的:

[{
  "url": "https://en.wikipedia.org/wiki/List_of_hedge_funds",
  "pageTitle": "List of hedge funds - Wikipedia",
  "links": [
    "/wiki/Bridgewater_Associates",
    "/wiki/Westport,_Connecticut",
    "/wiki/Renaissance_Technologies",
    "/wiki/East_Setauket,_New_York",
    "/wiki/Man_Group",
    "/wiki/London",
    "/wiki/AQR_Capital_Management",
    "/wiki/Greenwich,_Connecticut",
    "/wiki/Two_Sigma_Investments",
    "/wiki/New_York_City,_New_York",
    "/wiki/Millennium_Management,_LLC",
    "/wiki/New_York_City,_New_York",
    "/wiki/Elliott_Management",
    "/wiki/New_York_City,_New_York",
    "/wiki/BlackRock",
    "/wiki/New_York_City,_New_York",
    "/wiki/Citadel_LLC",
    "/wiki/Chicago,_IL",
    "/wiki/Davidson_Kempner_Capital_Management",
    "/wiki/New_York_City,_New_York",
    "/wiki/Viking_Global_Investors",
    "/wiki/Greenwich,_Connecticut",
    "/wiki/Baupost_Group",
    "/wiki/Boston,_MA",
    "/wiki/D.E._Shaw_%26_Co.",
    "/wiki/New_York_City,_New_York",
    "/wiki/Farallon_Capital",
    "/wiki/San_Francisco,_CA",
    "/wiki/Marshall_Wace",
    "/wiki/London",
    "/wiki/The_Children%27s_Investment_Fund_Management",
    "/wiki/London",
    "/wiki/Wellington_Management_Company",
    "/wiki/Boston,_MA",
    "/wiki/Winton_Group",
    "/wiki/London",
    "/wiki/Capula_Investment_Management",
    "/wiki/London",
    "/wiki/York_Capital_Management",
    "/wiki/New_York_City,_NY"
  ]
}]

我使用以下代码作为我的 pageFunction .

page功能

// The function accepts a single argument: the "context" object.
// For a complete list of its properties and functions,
// see https://apify.com/apify/web-scraper#page-function 
async function pageFunction( context ) {
    const url = 'https://en.wikipedia.org/wiki/List_of_hedge_funds';
    const TITLE_SELECTOR = 'title';
    const ANCHOR_SELECTOR = 'tr > td > a';
    const HREF_SELECTOR = 'href';

    // jQuery is handy for finding DOM elements and extracting data from them.
    //  To use it, make sure to enable the "Inject jQuery" option.
    const $ = context.jQuery;
    const pageTitle = $( TITLE_SELECTOR ).first().text();
    const anchorTag = $( ANCHOR_SELECTOR );
    const links = [];
    anchorTag.each((index, item,) => {
      const link = $(item).attr( HREF_SELECTOR );
      if( link ) links.push( link );
    });

    return {
      url: context.request.url,
      pageTitle,
      links,
    };
}

我需要如何更改我的代码?

1 回复 | 直到 6 年前

marc_s MisterSmith 6 年前

它看起来不错,您需要更改对表中数据的解析。这里有一个pageFunction的例子。

// The function accepts a single argument: the "context" object.
// For a complete list of its properties and functions,
// see https://apify.com/apify/web-scraper#page-function 
async function pageFunction( context ) {
    const url = 'https://en.wikipedia.org/wiki/List_of_hedge_funds';
    const TITLE_SELECTOR = 'title';
    const ANCHOR_SELECTOR = 'tr > td > a';
    const LINE_SELECTOR = '.wikitable tr'
    const HREF_SELECTOR = 'href';

    // jQuery is handy for finding DOM elements and extracting data from them.
    //  To use it, make sure to enable the "Inject jQuery" option.
    const $ = context.jQuery;
    const pageTitle = $( TITLE_SELECTOR ).first().text();
    const anchorTag = $( ANCHOR_SELECTOR );
    const lines = $( LINE_SELECTOR );
    const links = [];
    lines.each((index, item) => {
        const columns = $(item).find('td');
        const link = {
          firmName: columns.eq(1).text().trim(),
          firmUrl: columns.eq(1).find('a').eq(0).attr('href'),
          hq: columns.eq(2).text().trim(),
          hqUrl: columns.eq(2).find('a').eq(0).attr('href'),
        }
        if (link.firmUrl) {
            links.push(link);
        }       
    });

    return {
      url: context.request.url,
      pageTitle,
      links,
    };
}