1

使用 Apify 和 Puppeteer，我想从以下 URL 抓取数据表：

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

我希望结果是一个对象数组。数组的每个元素应该代表<tr>原始数据源表的每一行，并且是一个具有以下属性的 JS 对象。

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

在哪里：

  • firmName是每行.innerText()的第一个元素。<td>
  • firmUrl是每行href第一个元素的属性。<td>
  • hq是每行. innerText()的第二个元素。<td>
  • hqUrl是每一行的第二个元素的href属性。<td>
  • aum是每一行. innerText()的第三个<td>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，替代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，或者，对象可能如下（我不知道哪个是可能的，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
]

但相反，我实际上看到了以下结果。

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.

页面函数 
// 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？

4

1 回答 1

2

看起来不错，您需要更改表中数据的解析。有一个 pageFunction 的例子可以工作。

// 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,
    };
}
于 2020-03-02T15:41:21.597 回答