javascript - TypeError : C:\nodetest1\views\userlist. Jade :7

Question

当我尝试从我的 Mongodb 中提取我的用户集合时，出现了上述错误。相关代码如下，任何关于为什么会发生这种情况的帮助将不胜感激。

错误

C:\nodetest1\views\userlist.jade:7 5| User List 6| ul > 7| each user, i in userlist 8|      li 9| a(href="mailto:#{user.email}")= user.username Cannot read property 'length' of   undefined

TypeError: C:\nodetest1\views\userlist.jade:7
5|         User List
6|     ul

7| each user, i in userlist 8| li 9| a(href="mailto:#{user.email}")= user.username

Cannot read property 'length' of undefined
at eval (eval at <anonymous> (C:\nodetest1\node_modules\jade\lib\jade.js:172:8),   <anonymous>:50:31)
at eval (eval at <anonymous> (C:\nodetest1\node_modules\jade\lib\jade.js:172:8),   <anonymous>:93:4)
at eval (eval at <anonymous> (C:\nodetest1\node_modules\jade\lib\jade.js:172:8), <anonymous>:106:21)
at res (C:\nodetest1\node_modules\jade\lib\jade.js:173:38)
at Object.exports.render (C:\nodetest1\node_modules\jade\lib\jade.js:269:10)
at Object.exports.renderFile (C:\nodetest1\node_modules\jade\lib\jade.js:305:18)
at View.exports.renderFile [as engine]      (C:\nodetest1\node_modules\jade\lib\jade.js:290:21)
at View.render (C:\nodetest1\node_modules\express\lib\view.js:76:8)
at Function.app.render (C:\nodetest1\node_modules\express\lib\application.js:502:10)
at ServerResponse.res.render (C:\nodetest1\node_modules\express\lib\response.js:777:7)

路线

var express = require('express');
var router = express.Router();

/* GET users listing. */
router.get('/', function(req, res) {
res.send('respond with a resource');
});
module.exports = router;

users.js 路由

var express = require('express');
var router = express.Router();

/* GET users listing. */
router.get('/', function(req, res) {
res.send('respond with a resource');
});

module.exports = router;

app.js

var express = require('express');
var path = require('path');
var favicon = require('static-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var routes = require('./routes/index');
var users = require('./routes/users');

var app = express();

// New Code
var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/nodetest1');

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(favicon());
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded());
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

// Make our db accessible to our router
app.use(function(req,res,next){
req.db = db;
next();
});

app.use('/', routes);
app.use('/users', users);

/// catch 404 and forwarding to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});

 /// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: err
    });
});
}

 // production error handler
 // no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
    message: err.message,
    error: {}
});
});
module.exports = app;

用户 ListView

extends layout

block content
h1.
    User List
ul
    each user, i in userlist
        li
            a(href="mailto:#{user.email}")= user.username

Answer 1

我有同样的错误，解决方案是您可能关闭了与 MongoDB 的连接，它在前面的步骤中在控制台窗口中运行。

重新连接到数据库:

mongod --dbpath data/

然后在第二个控制台中运行:

npm start

并将您的浏览器指向 localhost:3000，一切都应该正常。

这段代码来自优秀Node Tutorial by Christopher Buecheler .