Question

我试图用mlab发出一个find（）请求。我在我的主文件（Controller）中使用express将它路由到我的模型中的函数，并在那里从DB执行find（）。当应用程序输入此功能时，它可能仍然没有连接到数据库，因此conn.once中的代码不会运行。

所以我在方法中移动了mongooe.connect，现在客户端得到了一个空答案。我认为控制者在找到之前回答了答案。

//index.js (the controller)

    const   express     = require('express');
    app         = express(),
    data        = require('./data/securitySettingsDB.json'),
    port        = process.env.PORT || 3000,
    bodyParser  = require('body-parser'),
    methods     = require('./modules');
    var method = methods();
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({extended: true }));

    app.use(express.static('public'));
    app.get('/', (req,res) => {
        console.log('Trace: API Page');
        res.sendFile(__dirname + '/api/index.html');
    });
    app.get('/getAllUsers/', (req, res) => {
      res.setHeader('Debug', 'getAllUsers was reached');
      res.status(200).json(method.getAllUsers());
    });

    app.listen(port);
    console.log('listening on port ${port}');

//模块

    const consts      = require('../models/consts'),
          mongoose    = require('mongoose');
    var User = require('../models/user');
    class Methods {

      getAllUsers() {
          console.log("Trace : getAllUsers()");
          mongoose.connect(consts.MLAB_KEY);
          conn.on('error', (err) => {
             console.log(`connection error: ${err}`);
          });
          conn.once('open', () => {
             console.log(`once`);
             User.find({}, (err, user) => {
               if(err){
                 console.log(`query error ${err}`);
                 mongoose.disconnect();
               return {"error": err}
               }
               else console.log(`ok`);
               console.log(user);
               mongoose.disconnect();
               return user;
          });
      });
     console.log(`returned from query`);
     }
    module.exports = function() {
    var methods = new Methods();
    return methods;
    }

模型

var mongoose = require('mongoose'),
schema = mongoose.Schema,
userSchema = new schema({
user_name:  {type:String, index:1, required:true, unique:true},
password:   {type:String, required:true},
email:      {type:String, required:true},
first_name: {type:String, required:true},
last_name:  {type:String, required:true},
settings:   {
  login_alerts: {type:Boolean, required:true},
  recognized_devices: [String]
},
phone_to_aproove_password_change: String
});

var User = mongoose.model('User', userSchema);
module.exports = User;

Answer 1

Node.js是异步的。你需要做一些修复：

 getAllUsers(clb) {
  console.log("Trace : getAllUsers()");
  mongoose.connect(consts.MLAB_KEY);
  conn.on('error', (err) => {
     console.log(`connection error: ${err}`);
  });
  conn.once('open', () => {
     console.log(`once`);
     User.find({}, (err, user) => {
       if(err){
         console.log(`query error ${err}`);
         mongoose.disconnect();
         return clb({"error": err});
       }
       else console.log(`ok`);
       console.log(user);
       mongoose.disconnect();
       clb(null, user);
  });

并像这样使用

app.get('/getAllUsers/', (req, res) => {
      method.getAllUsers(function(err, users){
         if(err){
            throw err;
         }
         res.setHeader('Debug', 'getAllUsers was reached');
         res.status(200).json(users);
        });
      })
  });

mongoose.find（）在向客户端返回答案后发生

1 个答案: