简单的数据库mongo查询出错了？

Question

Hey I am trying to query the database (mongodb) from my index.js file then return the value from the query into a variable so I can then use that variable to show the persons information on the website. I currently have this code up but it is giving me problems. Trying to figure out how to query it the right way. I am querying the email but I want to extract the first name based on an email query. I am using node.js and jade for my view engine.

var mongoose = require('mongoose')
  , db = mongoose.createConnection('mongodb://localhost/test5');

var user = function (name) { 
    var name = db.users.find({ email: 'works@gmail.com' }).pretty();
    console.log(name); 
    return name;
};

exports.index = function(req, res) {
    res.render('index', { title: 'Weblio', user: user});
};

Answer 1

It looks like you're using Mongoose, so what I'd suggest is that you use their querying functions which have worked well for me in the past. It also helps to establish Mongoose models for your data stored in MongoDB.

Try this (note: it is untested, but I pulled it from a functioning program):

var mongoose = require('mongoose')
    , Schema = mongoose.Schema;

mongoose.connect('mongodb://localhost/test5');

var UserSchema = new Schema({
    email: { type: String, index: true },
    firstName: { type: String },
    lastName: { type: String }
});

mongoose.model('User', UserSchema);

var User = mongoose.model('User');

exports.index = function(req, res) {
    User.findOne({
        email: "someone@something.com"
    }, function(err, user) {
       if(err) {
           res.send(err);
       } else {
           console.log(user.firstName);
           res.render('index', {title: 'Weblio', user: user.firstName});
       }
    });
}

Answer 2

Nearly all IO in node is asynchronous which means that your find method isn't going to return the actual result but a promise or it is expecting a callback that it will call with the result.

Try this:

var mongoose = require('mongoose')
  , db = mongoose.createConnection('mongodb://localhost/test5');


exports.index = function(req, res) {
  db.users.find({ email: 'works@gmail.com' }, function(err, data){
    if(err){
      return req.send(500);
      }
    res.render('index', { title: 'Weblio', user: JSON.stringify(data)});
    });
};