Question

我尝试使用express.js在node.js上创建一个简单的CRUD应用程序。我尝试连接到DB，但是我有一个错误TypeError: Cannot call method 'get' of undefined。我的部分代码：

app.js

var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/notepad');

var app = express();

app.get('/users', routes.userlist);

// mongoDB
app.use(function (req, res, next) {
   req.db = db; // this is setting up db property to request
   next();
});

路由/ index.js

exports.userlist = function (req, res) {
var db = req.db;
var collection = db.get('usercollection'); // error in this line
collection.find({}, {}, function (e, docs) {
    res.render('userList', {
        "userlist": docs
    });
});
};

我认为数据库的实例未设置或在其他文件中不可用。怎么解决这个问题？

Answer 1

您的app.use应该在app.get之前写下来。快递首先调用app.get。

var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/notepad');

var app = express();

// mongoDB
// Do all your "pre-route" use() functions first
app.use(function (req, res, next) {
   req.locals.db = db; // this is setting up db property to request
   next();
});

app.get('/users', routes.userlist);

在你的路线......

var db = req.locals.db; // Instead of req.db

甚至更好......

var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/notepad');

var app = express();

app.locals.db = db;

app.get('/users', routes.userlist); // Access it using req.locals.db

TypeError：无法调用方法＆＃39; get＆＃39;未定义的

1 个答案: