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Node.js在另一个方法完成后调用一个方法

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Eunicorn · 技术社区 · 8 年前

我想在“app.get('/news/api/:newsName',函数(req,res)”完成后调用“app.get('/news/news desc',(req,res)”方法。

这是我的代码:

let articleUrlArray = [];

app.get('/news/api/:newsName', function(req, res) {
  const API_KEY = 'example';

  let data = '';

  const techCrunchURL = `https://newsapi.org/v2/top-headlines?sources=techcrunch&apiKey=${API_KEY}`

  switch(req.params.newsName) {
    case 'tech-crunch':
      request(techCrunchURL, function(err, response, html) {
    
        let formattedData = JSON.parse(response.body);

        for(let i = 0; i < formattedData.articles.length; i++) {
          articleUrlArray.push(formattedData.articles[i].url);
        }

        data = response.body;
        res.setHeader('Content-Type', 'application/json');
        res.send(data);
      });

      break;

    default:
      data = 'Please type in correct news source';
      break;
  }
})

const checkBody = res => (err, response, html) => {
    const $ = cheerio.load(html);
    const articleContent = $('.article-content').children('p')
    const bodyOne = articleContent.eq(0).text()
    const bodyTwo = articleContent.eq(1).text()
    const isExtensive = bodyOne.split(' ').length > 50
    res(isExtensive ? { bodyOne } : { bodyOne, bodyTwo })
}

const getArticle = article => new Promise(res => request(article, checkBody(res)))

app.get('/news/news-desc', (req, res) => {
    Promise.all(articleUrlArray.map(getArticle)).then(data => res.send(JSON.stringify(data)))
})

如您所见,第一个方法调用“newsapi.org”,得到10篇文章。然后它只提取这些文章的url并将它们推送到articleUrlArray中。

将url推入articleUrlArray之后,它将如下所示:

let articleUrlArray = [ 'https://techcrunch.com/2018/05/19/shared-housing-startups-are-taking-off/',
  'https://techcrunch.com/2018/05/19/shared-housing-startups-are-taking-off/',
  'https://techcrunch.com/2018/05/19/my-data-request-lists-guides-to-get-data-about-you/',
  'https://techcrunch.com/2018/05/19/siempos-new-app-will-break-your-smartphone-addiction/',
  'https://techcrunch.com/2018/05/19/la-belle-vie-wants-to-compete-with-amazon-prime-now-in-paris/',
  'https://techcrunch.com/2018/05/19/apple-started-paying-15-billion-european-tax-fine/',
  'https://techcrunch.com/2018/05/19/original-content-dear-white-people/',
  'https://techcrunch.com/2018/05/19/meet-the-judges-for-the-tc-startup-battlefield-europe-at-vivatech/',
  'https://techcrunch.com/2018/05/18/nasas-newest-planet-hunting-satellite-takes-a-stellar-first-test-image/',
  'https://techcrunch.com/video-article/turning-your-toys-into-robots-with-circuit-cubes/',
  'https://techcrunch.com/2018/05/18/does-googles-duplex-violate-two-party-consent-laws/' ];

它只会被url填满。

然后第二个方法,将使用填充的articleUrlArray来做自己的事情。

但是,目前对于我的代码,第二个方法在articleUrlArray被填充之前首先运行。

我想在第一个方法完成并且articleUrlArray已填充了url之后运行第二个方法。

你能帮我做这个吗?

2 回复 | 直到 8 年前

Hugo Nasciutti 8 年前

let articleUrlArray = [];
const addArticleUrl = url => articleUrlArray.push(url)

const checkBody = res => (err, response, html) => {
  const $ = cheerio.load(html);
  const articleContent = $('.article-content').children('p')
  const bodyOne = articleContent.eq(0).text()
  const bodyTwo = articleContent.eq(1).text()
  const isExtensive = bodyOne.split(' ').length > 50
  res(isExtensive ? { bodyOne } : { bodyOne, bodyTwo })
}

const getArticle = article => new Promise(res => request(article, checkBody(res)))

const newsDescMiddleware = app.get('/news/news-desc', (req, res) => {
  Promise.all(articleUrlArray.map(getArticle)).then(data => res.send(JSON.stringify(data)))
})

const techCrunch = res => url => request(url, (err, response, html) => {
  let formattedData = JSON.parse(response.body);
  formattedData.articles.forEach(article => addArticleUrl(article.url))
  res(response.body)
})

const getNewsByName = (newsName, url) => new Promise((res, reject) => ({
  'tech-crunch': techCrunch(res)(url)
}[newsName])) || reject()

const getNewsByNameMiddleware = (req, res) => {
  const API_KEY = 'example';
  const techCrunchURL = `https://newsapi.org/v2/top-headlines?sources=techcrunch&apiKey=${API_KEY}`

  getNewsByName(req.params.newsName, url)
    .then(body => {
      res.setHeader('Content-Type', 'application/json');
      res.send(body)
    })
    .catch(() => res.send('Please type in correct news source'))
}

app.get('/news/api/:newsName', getNewsByNameMiddleware, newsDescMiddleware)

在这里,我给你做了一些中间产品。

我假设您不需要前一个中间件的响应。

我喜欢按职责划分代码,并按功能编写代码。

Cisco 8 年前

如果您愿意的话,您可以将第一条函数路由的核心逻辑分离出来,并在这两个地方重用它。但是,您仍然需要提供newsName参数来获取'/news/news desc'端点。

代码示例。

    let articleUrlArray = [];

    function getNewsNames(newsName, callback) {
        const API_KEY = 'example';
        let data = '';
        const techCrunchURL = `https://newsapi.org/v2/top-headlines?sources=techcrunch&apiKey=${API_KEY}`

        switch (newsName) {
            case 'tech-crunch':
                request(techCrunchURL, function (err, response, html) {

                    let formattedData = JSON.parse(response.body);

                    for (let i = 0; i < formattedData.articles.length; i++) {
                        articleUrlArray.push(formattedData.articles[i].url);
                    }

                    data = response.body;
                    callback(null, data);
                });

                break;

            default:
                data = 'Please type in correct news source';
                callback('Error', data);
                break;
        }
    }

    app.get('/news/api/:newsName', function (req, res) {

        getNewsNames(req,params.newsName, (err, data) => {
            if (!err) {
                res.setHeader('Content-Type', 'application/json');
            }

            return res.send(data);
        })
    })

    const checkBody = res => (err, response, html) => {
        const $ = cheerio.load(html);
        const articleContent = $('.article-content').children('p')
        const bodyOne = articleContent.eq(0).text()
        const bodyTwo = articleContent.eq(1).text()
        const isExtensive = bodyOne.split(' ').length > 50
        res(isExtensive ? { bodyOne } : { bodyOne, bodyTwo })
    }

    const getArticle = article => new Promise(res => request(article, checkBody(res)))

    app.get('/news/news-desc/:newsName', (req, res) => {
        getNewsNames(req.params.newsName, (err, data) => {
            // by now, the articleUrlArray array will be filled
            Promise.all(articleUrlArray.map(getArticle)).then(data => res.send(JSON.stringify(data)))
        })
    })