检查sequelize中的mysql连接 [英] Check mysql connection in sequelize

问题描述

我有一个非常简单的程序，在其中创建Sequelize实例，然后在mysql数据库上执行原始查询. 这种情况是，当MySql启动并运行时没有问题，我可以毫无问题地执行查询. 但是，当MySql没有运行时，查询不会发出任何错误，直到达到查询超时为止，然后发出ETIMEOUT错误.但这不是真的发生了什么.我希望查询会发出ENOTFOUND错误或类似的信息(如果mysql未运行)，因此如果Mysql出现故障或Mysql很忙并且响应时间非常长，我可以管理该错误并执行不同的操作. 我应该做些什么来检查Mysql是否已启动并正在运行，而不必等待超时异常.

I have a very simple program in where I create a Sequelize instance and then I perform a raw query on a mysql database. The case is that when MySql is up and running there is no problem, I can perform the query with no problems. But when MySql is not running then the query doesn't emmit any error until the query timeout has reached and then it emmits a ETIMEOUT error. But that's not really what's happening. I expect the query to emit ENOTFOUND error or something like that if mysql is not running so I can manage the error and perform different actions if Mysql has gone down or Mysql is very busy and has a very large response time. What shoul'd I do to check if Mysql is up and running without having to wait the timeout exception.

sequelize = new Sequelize(db_name, db_user, db_pass, opts);

sequelize.query('SELECT * FROM some_table').success(function(result) {
  console.log(result);
}).error(function(err) {
  console.log(err);
});

推荐答案

最新版本为 Sequelize (即3.3.2)， authenticate 可以用来检查连接:

As of latest version of Sequelize (i.e. 3.3.2), authenticate can be used to check the connection:

var sequelize = new Sequelize("db", "user", "pass");

sequelize.authenticate().then(function(errors) { console.log(errors) });

authenticate只需运行SELECT 1+1 AS result查询来检查数据库连接.

authenticate simply runs SELECT 1+1 AS result query to check the db connection.

更新:

最新的API 导致的错误在catch中处理:

Errors by the newest API need to be handled in catch:

sequelize
  .authenticate()
  .then(() => {
    console.log('Connection has been established successfully.');
  })
  .catch(err => {
    console.error('Unable to connect to the database:', err);
  });

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