Puppeteer：从数据库中的 for 循环保存数据

Question

我正在抓取网站并设法在 for 循环中提取数据。

但是，我不知道如何将它保存到我的 MongoDB 数据库中，因为我收到错误消息 ReferenceError: nameElement is not defined。

如何将 for 循环的结果作为对象保存到数据库中？

const kclResults = [];

async function scrapeInfiniteScrollItems(
  page,
  scrollDelay = 10000
) {
  try {
    const html = await page.content();
    const $ = cheerio.load(html);

    await page.evaluate(() => {
      let elements = $("[role='listitem']")
        .find("._2DX0iPG8PDF3Si_o5PlzIj")
        .toArray();

      for (i = 0; i < elements.length; i++) {
        $(elements[i]).click();
        const nameElement = $("[data-log-name='PersonName']").text();
        const emailElement = $("[data-log-name='Email']").text();
        const allElements = $("[aria-label='Contact information']").text();
        const officeLocation = $("[data-log-name='OfficeLocation']").text();
        const position = $("[data-log-name='Company']").text();
        const jobTitle = $("[data-log-name='JobTitle']").text();
        const departament = $("[data-log-name='Department']").text();
        console.log(
          `email: ${emailElement} name: ${nameElement} allElements: ${allElements} \n office location: ${officeLocation} \n position: ${position} \n jobTitle: ${jobTitle} \n departament: ${departament}`
        );
      }
    });


    let kclResult = new KingsDB({
      nameElement,
      emailElement,
      allElements,
      officeLocation,
      position,
      jobTitle,
      departament,
    });

    kclResults.push(kclResult);
    console.log(kclResults);
    kclResult.save();
    return kclResults;
  } catch (error) {
    console.log(error);
  }
}

Answer 1

您正在 for 循环范围内声明 nameElement（和其他变量）并试图在该范围外访问它。

只需创建一个“元素”数组，然后在将其写入数据库时对其进行迭代。下面的代码应该可以工作：

const kclResults = [];

async function scrapeInfiniteScrollItems(
    page,
    scrollDelay = 10000
) {
    try {
        const html = await page.content();
        const $ = cheerio.load(html);



        const resultArr = await page.evaluate(() => {
            let elements = $("[role='listitem']")
                .find("._2DX0iPG8PDF3Si_o5PlzIj")
                .toArray();
            const resultArr = [];

            for (i = 0; i < elements.length; i++) {
                $(elements[i]).click();
                const nameElement = $("[data-log-name='PersonName']").text();
                const emailElement = $("[data-log-name='Email']").text();
                const allElements = $("[aria-label='Contact information']").text();
                const officeLocation = $("[data-log-name='OfficeLocation']").text();
                const position = $("[data-log-name='Company']").text();
                const jobTitle = $("[data-log-name='JobTitle']").text();
                const departament = $("[data-log-name='Department']").text();
                resultArr.push({
                    nameElement,
                    emailElement,
                    allElements,
                    officeLocation,
                    position,
                    jobTitle,
                    departament
                });
                console.log(
                    `email: ${emailElement} name: ${nameElement} allElements: ${allElements} \n office location: ${officeLocation} \n position: ${position} \n jobTitle: ${jobTitle} \n departament: ${departament}`
                );
            }
            return resultArr;

        });

        const kclResults = [];
        for (let result of resultArr) {
            const {
                nameElement,
                emailElement,
                allElements,
                officeLocation,
                position,
                jobTitle,
                departament
            } = result;
            let kclResult = new KingsDB({
                nameElement,
                emailElement,
                allElements,
                officeLocation,
                position,
                jobTitle,
                departament,
            });

            kclResults.push(kclResult);
            console.log(kclResults);
            kclResults.push(kclResult.save());
        }
        return kclResults;
    } catch (error) {
        console.log(error);
    }
}

PS：传递给 pageEvaluate 的函数在浏览器上下文中运行，因此无法访问您的节点变量，直到它们作为参数显式传递.

Puppeteer：从数据库中的 for 循环保存数据

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javascript

mongodb

web-scraping

puppeteer