Javascript Module.exports返回未定义的Mongoose调用_Javascript_Node.js_Mongodb

Javascript Module.exports返回未定义的Mongoose调用

javascript node.js mongodb

Javascript Module.exports返回未定义的Mongoose调用,javascript,node.js,mongodb,Javascript,Node.js,Mongodb,在我与猫鼬的find通话中，我不断收到undefined返回。我的成绩在我的导出中，文件不会被记录，但如果我在我的项目之外返回一个简单字符串，它就会工作。find调用我正在传递req和res，它们正确地记录在我的导出文件中，因此不认为它们与问题有关。你知道怎么回事吗 routes.js var proj = require('./exports/projects'); app.use(function(req, res, next){ //repsonse: undefined

在我与猫鼬的

find

通话中，我不断收到

undefined

返回。我的成绩在我的导出中，文件不会被记录，但如果我在我的

项目之外返回一个简单字符串，它就会工作。find

调用

我正在传递

req

和

res

，它们正确地记录在我的导出文件中，因此不认为它们与问题有关。你知道怎么回事吗

routes.js

var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

导出/projects.js

var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

models/projects.js

var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

这是由于

Project.find（）方法的异步性质造成的。您正试图在异步函数中返回一个值，该函数将在一段时间后完成。因此，当在console.log（'response:'+proj.test（req，res））中执行proj.test（req，res）
时，is会返回未定义的值
解决方案
需要传递回调函数，该函数在find
操作完成后执行
routes.js
var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

导出/projects.js
var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

这是由于Project.find（）方法的异步性质造成的。您正试图在异步函数中返回一个值，该函数将在一段时间后完成。因此，当在console.log（'response:'+proj.test（req，res））中执行proj.test（req，res）
时，is会返回未定义的值
解决方案
需要传递回调函数，该函数在find
操作完成后执行
routes.js
var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

导出/projects.js
var proj = require('./exports/projects');

app.use(function(req, res, next){
    //repsonse: undefined
    console.log('response: ' + proj.test(req, res));
    next();
});

var Projects = require('../models/projects');

module.exports = {
    test: function(req, res) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return '1';
                if (!result)
                    return null;
                else
                    return result;
        });
    }
};

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

var Projects = new Schema({
        projectid: String,
        pname: { type: String, required: true, trim: true },
        owner: { type: String, required: true, trim: true },
        status: { type: String, default: '0' },
        team: String,
        archived: { type: Boolean, default: '0' },
        created_at: Date
});

Projects.pre('save', function(next) {
    var currentDate = new Date();
    this.created_at = currentDate;
    this.projectid = shortid.generate();
    next();
});

module.exports = mongoose.model('Projects', Projects);

app.use(function(req, res, next){

    proj.test(req,res,function(result){
      console.log('response',result);
    });
    next();
});

module.exports = {
    test: function(req, res, cb) {
        Projects.find({'owner':req.user.id}, function(err, result) {
                if (err) return cb(1);
                if (!result)
                    return cb(null);
                else
                    return cb(result);
        });
    }
};

回答得很好，谢谢，我知道这与此有关，但我在导出方面也有类似的情况，似乎不需要回调，但那一定是因为页面被呈现了。再次感谢您的全面回答！回答得很好，谢谢，我知道这与此有关，但我在导出方面也有类似的情况，似乎不需要回调，但那一定是因为页面被呈现了。再次感谢您的全面回答！