javascript - 我无法更改在函数外部初始化的对象的值，或者函数根本没有运行 - 使用 npm 和 nodejs

Question

我正在建立一个社交网络 - 为此我使用 nodejs。我是这个主题的新手，这是我关于这个主题的第一篇文章，如果你能理解我，我会很高兴。

在我的社交网络中，我想使用“npm”kmeans 算法中的算法。

我正在尝试在我的项目中运行从 npm 下载的库 - 但我不确定问题是什么。我认为这个问题非常小，但是我坐了几个小时却无法弄清楚。

我正在添加到目前为止我所做的代码：

//kmeans.js file

const kmeans = require('kmeans-engine');

exports.addUserkMeansMatch = (req, res) => {
  const engineers = [
    // frontend engineers
    { html: 5, angular: 5, react: 3, css: 3 },
    { html: 4, react: 5, css: 4 },
    { html: 4, react: 5, vue: 4, css: 5 },
    { html: 3, angular: 3, react: 4, vue: 2, css: 3 },

    // backend engineers
    { nodejs: 5, python: 3, mongo: 5, mysql: 4, redis: 3 },
    { java: 5, php: 4, ruby: 5, mongo: 3, mysql: 5 },
    { python: 5, php: 4, ruby: 3, mongo: 5, mysql: 4, oracle: 4 },
    { java: 5, csharp: 3, oracle: 5, mysql: 5, mongo: 4 },

    // mobile engineers
    { objc: 3, swift: 5, xcode: 5, crashlytics: 3, firebase: 5, reactnative: 4 },
    { java: 4, swift: 5, androidstudio: 4 },
    { objc: 5, java: 4, swift: 3, androidstudio: 4, xcode: 4, firebase: 4 },
    { objc: 3, java: 5, swift: 3, xcode: 4, apteligent: 4 },

    // devops
    { docker: 5, kubernetes: 4, aws: 4, ansible: 3, linux: 4 },
    { docker: 4, marathon: 4, aws: 4, jenkins: 5 },
    { docker: 3, marathon: 4, heroku: 4, bamboo: 4, jenkins: 4, nagios: 3 },
    { marathon: 4, heroku: 4, bamboo: 4, jenkins: 4, linux: 3, puppet: 4, nagios: 5 }
  ];
  resultFromKmeans = {check : " this is changed?"};
  kmeans.clusterize(engineers, { k: 4, maxIterations: 5, debug: true }, (err, result) => {
    console.log('----- Results -----');
    console.log(`Iterations: ${result.iterations}`);
    console.log('Clusters: ');
    console.log(result.clusters);
    resultFromKmeans = { ...result.clusters}; //<-- here is the problem. this not override "resultFromKmeans".
  })
  return res.json(resultFromKmeans);
};

//index.js file

const {
  addUserkMeansMatch
} = require('kmeans.js');


app.get('/kmeans', addUserkMeansMatch);
exports.api = functions.region('europe-west1').https.onRequest(app);

问题是：它想从 addUserkMeansMatch 函数中获取，目前只有关于找到的集群的信息，所以我用我想要的结果初始化 resultFromKmeans 对象。但是好像我没有进入函数，或者运行函数时resultFromKmeans的值没有变化。我不知道该怎么办。

编辑 这是修改后的代码，但我不明白。我不懂为什么

//Add user k-means matches
exports.addUserKmeansMatch = (req, res) => {
  const engineers = [
    // frontend engineers
    { html: 5, angular: 5, react: 3, css: 3 },
    { html: 4, react: 5, css: 4 },
    { html: 4, react: 5, vue: 4, css: 5 },
    { html: 3, angular: 3, react: 4, vue: 2, css: 3 },

    // backend engineers
    { nodejs: 5, python: 3, mongo: 5, mysql: 4, redis: 3 },
    { java: 5, php: 4, ruby: 5, mongo: 3, mysql: 5 },
    { python: 5, php: 4, ruby: 3, mongo: 5, mysql: 4, oracle: 4 },
    { java: 5, csharp: 3, oracle: 5, mysql: 5, mongo: 4 },

    // mobile engineers
    { objc: 3, swift: 5, xcode: 5, crashlytics: 3, firebase: 5, reactnative: 4 },
    { java: 4, swift: 5, androidstudio: 4 },
    { objc: 5, java: 4, swift: 3, androidstudio: 4, xcode: 4, firebase: 4 },
    { objc: 3, java: 5, swift: 3, xcode: 4, apteligent: 4 },

    // devops
    { docker: 5, kubernetes: 4, aws: 4, ansible: 3, linux: 4 },
    { docker: 4, marathon: 4, aws: 4, jenkins: 5 },
    { docker: 3, marathon: 4, heroku: 4, bamboo: 4, jenkins: 4, nagios: 3 },
    { marathon: 4, heroku: 4, bamboo: 4, jenkins: 4, linux: 3, puppet: 4, nagios: 5 }
  ];
  kmeans.clusterize(engineers, { k: 4, maxIterations: 5, debug: true }, (err, result) => {
    res.json(result.cluster111111s)
    .catch((err) => {
      console.error(err);
      return res.status(500).json({ error: err.code });
    });
  })
};

标签： javascriptnode.jsnpm

Answer 1

您遇到的问题是您res.json(resultFromKmeans)在更新之前返回。当您kmeans.clusterize在上面的代码中使用时，您正在为其附加一个回调，这实际上是说，“嘿，当您完成运行 clusterize 时，您可以使用结果调用此函数以便我可以处理它吗？”。但是因为您在值完成之前将其发回，所以您会得到错误的结果。

等待结果的最简单方法是res.json()从回调中调用。不要忘记处理的值err！

const kmeans = require('kmeans-engine');

exports.addUserkMeansMatch = (req, res) => {
  const engineers = [ /* ... */ ];
  kmeans.clusterize(engineers, { k: 4, maxIterations: 5, debug: true }, (err, result) => {
    console.log('----- Results -----');
    console.log(`Iterations: ${result.iterations}`);
    console.log('Clusters: ');
    console.log(result.clusters);
    res.json(result.clusters); // no need to clone it, just return it as-is.
  });
};