Question

我正在为我的项目使用ExpressJS 4，它遵循MVC架构。我创建了一个帮助程序，我可以编写常用的函数来查询来自DB的数据（DRY方法），这些函数可以从任何控制器访问。我能够调用辅助函数并将数据传递给它，但是我无法从中查询数据库。

这是我的控制器示例（dumyController.js）：

'use strict';
var dbHelpers = require('../helpers/helpers');

exports.dummyFunction = function (req, res) {
    var id=165;
    var abc = dbHelpers.dummyHelperFunction(iddd);
    console.log(abc);
};

正如您所看到的，我在控制器中调用辅助函数。这是帮助者的样本（helpers.js）

var db = require('../db');
module.exports = {
  dummyHelperFunction: function (passvar) {
    var params = [passvar];
    var query = `SELECT email FROM members where id=?`;
    return db.query(query, params);
  }
};

如果您想知道我的数据库连接是否有任何问题，则没有与此相关的问题。仍然，分享它（db.js）

var mysql = require('mysql');
var connection = mysql.createPool({
    host: '127.0.0.1',
    user: 'root',
    password: '',
    database: 'dumyDB'
});
module.exports = connection;

我试图获取MySQL查询返回的结果，但这是我在控制台时记录的内容。

Query {
  domain: null,
  _events: {},
  _eventsCount: 0,
  _maxListeners: undefined,
  _callback: undefined,
  _callSite:
   Error
       at Pool.query (_PROJECT-PATH_\node_modules\mysql\lib\Pool.js:199:23)
       at Object.dummyHelperFunction (_PROJECT-PATH_\helpers\helpers.js:18:15)
       at exports.dummyFunction (_PROJECT-PATH_\controllers\dumyController.js:227:25)
       at Layer.handle [as handle_request] (_PROJECT-PATH_\node_modules\express\lib\router\layer.js:95:5)
       at next (_PROJECT-PATH_\node_modules\express\lib\router\route.js:137:13)
       at Route.dispatch (_PROJECT-PATH_\node_modules\express\lib\router\route.js:112:3)
       at Layer.handle [as handle_request] (_PROJECT-PATH_\node_modules\express\lib\router\layer.js:95:5)
       at _PROJECT-PATH_\node_modules\express\lib\router\index.js:281:22
       at Function.process_params (sam_PROJECT-PATH_ple\node_modules\express\lib\router\index.js:335:12)
       at next (_PROJECT-PATH_\node_modules\express\lib\router\index.js:275:10),
  _ended: false,
  _timeout: undefined,
  _idleNext: null,
  _idlePrev: null,
  _idleStart: null,
  _idleTimeout: -1,
  _repeat: null,
  sql: 'SELECT email FROM members where id=?',
  values: [ 165 ],
  typeCast: true,
  nestTables: false,
  _resultSet: null,
  _results: [],
  _fields: [],
  _index: 0,
  _loadError: null }

Answer 1

将您的代码更改为类似下面给出的内容。 db.query（）是异步的

<强>控制器

'use strict';
var dbHelpers = require('../helpers/helpers');
exports.dummyFunction = function (req, res) {
    var user = {
        passvar: 165
    };
    dbHelpers.dummyHelperFunction(user, function (err, rows) {
        if (err) {
            res.json({ success: false, message: 'unable to fetch' });
        }
        else {
            res.json({ success: true, values: rows });
        }
    });
};

<强>辅助

var db = require('../db');
module.exports = {
  dummyHelperFunction: function (param, callback) {
    var params = [param.passvar];
    var query = `SELECT email FROM members where id=?`;
    return db.query(query, params, callback);
  }
};

nodejs-无法从辅助函数获取数据

1 个答案: