mysql - 错误 : Cannot enqueue Handshake after already enqueuing a Handshake

Question

我正在从不同来源获取新闻提要并添加到数据库，但我遇到异常

Error: Cannot enqueue Handshake after already enqueuing a Handshake. at Protocol._validateEnqueue (/home/vikas/node_modules/mysql/lib/protocol/Protocol.js:210:16) at Protocol._enqueue (/home/vikas/node_modules/mysql/lib/protocol/Protocol.js:139:13) at Protocol.handshake (/home/vikas/node_modules/mysql/lib/protocol/Protocol.js:52:23) at Connection.connect (/home/vikas/node_modules/mysql/lib/Connection.js:130:18) at storeNewsFeedsInDB (/home/vikas/NodeJS Practice/fetchNews.js:42:7) at newsapi.v2.everything.then.response (/home/vikas/NodeJS Practice/fetchNews.js:33:9) at tryCatcher (/home/vikas/node_modules/bluebird/js/release/util.js:16:23) at Promise._settlePromiseFromHandler (/home/vikas/node_modules/bluebird/js/release/promise.js:512:31) at Promise._settlePromise (/home/vikas/node_modules/bluebird/js/release/promise.js:569:18) at Promise._settlePromise0 (/home/vikas/node_modules/bluebird/js/release/promise.js:614:10) at Promise._settlePromises (/home/vikas/node_modules/bluebird/js/release/promise.js:693:18) at Async._drainQueue (/home/vikas/node_modules/bluebird/js/release/async.js:133:16) at Async._drainQueues (/home/vikas/node_modules/bluebird/js/release/async.js:143:10) at Immediate.Async.drainQueues (/home/vikas/node_modules/bluebird/js/release/async.js:17:14) at runCallback (timers.js:637:20) at tryOnImmediate (timers.js:610:5)

下面是我的代码

const NewsAPI = require('newsapi');
const newsapi = new NewsAPI('*****************************');

var mysql = require('mysql');
var con = mysql.createConnection({
  host: "****",
  user: "****",
  password: "****",
  database: "****"
});

var channels = ['bbc-news', 'the-verge', 'reuters', 'cnbc', 'bloomberg', 'economist', 'nytimes'];
var topics = ['technology', 'business', 'finance', 'tech', 'economics', 'company'];

for (var i = 0; i < channels.length; i++) {
  for (var j = 0; j < topics.length; j++) {
    newsapi.v2.everything({
      q: topics[j],
      // q: 'technology',
      sources: channels[i],
      // sources: 'bloomberg',
      // domains: 'bbc.co.uk, techcrunch.com',
      from: '2018-03-14',
      to: '2018-03-14',
      language: 'en',
      sortBy: 'relevancy',
      pageSize:100,
      page: 1
    }).then(response => {
      // console.log(response);
      for (var i = 0; i < response.articles.length; i++) {
        // console.log(response.articles[i].title);
        storeNewsFeedsInDB(response.articles[i].title, 
                            response.articles[i].description, 
                              response.articles[i].url);
      }
    });
  }
}

function storeNewsFeedsInDB(title, description, url) {
  con.connect(function(err) {
    if (err) throw err;
    console.log("Connected!");

    //Insert a record in the "newsfeeds" table:
    var sql = "INSERT IGNORE INTO newsfeeds (`title`, `description`, `url`) VALUES ('" 
                + title.replace(/'/g, "\\'") + "', '" + description.replace(/'/g, "\\'") + "', '" + url + "')";
                console.log(sql);
    con.query(sql, function (err, result) {
      if (err) throw err;
      console.log("1 record inserted");
    });
  });
}

Nodejs 和 Mysql 新手，请帮助我。

Answer 1

您正在从(嵌套)循环内部调用 storeNewsFeedsInDB，每次访问它时您都会调用 con.connect，这就是您收到“排队握手”错误的原因.看看one of mysql npm package test suites可以揭示，因为一旦进行了两次连续的 con.connect 调用就会抛出错误。

您只需从代码中删除 con.connect 调用即可，因为任何 query 调用都会隐式建立连接，as the docs say .