关于node.js：ExpressJS res.render()错误(JSON.stringify无法在循环引用上工作)

ExpressJS res.render() error (JSON.stringify can't work on circular reference)

这有什么不对？

res.render('/somepage', {user:req.session.user})

它导致

1	Converting circular structure to JSON

错误，(导致会话元素具有循环用户引用。)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

<wyn>
exports.home = function (req, res) {
var entityFactory = new require('../lib/entity-factory.js').EntityFactory();
entityFactory.get_job_task_lists({
callback : function (err, job_task_lists) {
res.render('home.jade', {
locals:{
title: 'Logged in.',
user:req.session.user, // does not work
job_task_lists:job_task_lists || []
}
});
}
});
};

</wyn>

我在node_modules/express/node_modules/connect/lib/middleware/session/memory.js中添加了一些日志记录

1
2
3
4
5
6
7
8

MemoryStore.prototype.set = function(sid, sess, fn){
var self = this;
process.nextTick(function(){

console.log(sess); //this is giving the output listed

self.sessions[sid] = JSON.stringify(sess);
...

就结构而言，这就是我期望会话的样子：

1
2
3
4
5
6
7
8
9
10
11

{ lastAccess: 1330979534026,
cookie:
{ path: '/',
httpOnly: true,
_expires: Tue, 06 Mar 2012 00:32:14 GMT,
originalMaxAge: 14399999 },
user: // this is the object I added to the session
{ id: 1,
username: 'admin',
password: '8e3f8d3a98481a9073d2ab69f93ce73b',
creation_date: Mon, 05 Mar 2012 18:08:55 GMT } }

但这是我发现的：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61

{ lastAccess: 1330979534079, // new session
cookie:
{ path: '/',
httpOnly: true,
_expires: Tue, 06 Mar 2012 00:32:14 GMT,
originalMaxAge: 14399999 },
user: // but here it is again, except now it's a mashup,
// containing members it shouldn't have, like locals,
// and, well, everything but the first 4 properties
{ id: 1,
username: 'admin',
password: '8e3f8d3a98481a9073d2ab69f93ce73b',
creation_date: '2012-03-05T18:08:55.701Z',
locals:
{ title: 'Logged in.',
user: [Circular], //and now it's circular
job_task_lists: [Object] },
title: 'Logged in.',
user: [Circular],
job_task_lists: [ [Object], [Object], [Object], getById: [Function] ],
attempts: [ '/home/dan/development/aqp/views/home.jade' ],
scope: {},
parentView: undefined,
root: '/home/dan/development/aqp/views',
defaultEngine: 'jade',
settings:
{ env: 'development',
hints: true,
views: '/home/dan/development/aqp/views',
'view engine': 'jade' },
app:
{ stack: [Object],
connections: 6,
allowHalfOpen: true,
_handle: [Object],
_events: [Object],
httpAllowHalfOpen: false,
cache: [Object],
settings: [Object],
redirects: {},
isCallbacks: {},
_locals: [Object],
dynamicViewHelpers: {},
errorHandlers: [],
route: '/',
routes: [Object],
router: [Getter],
__usedRouter: true },
partial: [Function],
hint: true,
filename: '/home/dan/development/aqp/views/home.jade',
layout: false,
isPartial: true } }

node.js:201
throw e; // process.nextTick error, or 'error' event on first tick
^
TypeError: Converting circular structure to JSON
at Object.stringify (native)
at Array.0 (/home/dan/development/aqp/node_modules/express/node_modules/connect/lib/middleware/session/memory.js:77:31)
at EventEmitter._tickCallback (node.js:192:40)

查看用户对象是如何嵌套的？

请注意，这次我没有明确地使用'locals'发送值，但最终只有一个(这就是循环引用的来源)。

看起来会话正用于将对象传输到视图。

这是我唯一的中间件(它只从会话中读取)：

1
2
3
4
5
6
7

function requiresAuthentication(req, res, next){
if (req.session.user){
next();
} else {
next(new Error('Unauthorized. Please log in with a valid account.'))
}
}

并且我唯一一次修改req.session就在这条路线上：

1
2
3
4
5
6
7
8
9
10
11
12
13
14

app.post('/home', function (req,res,next) {
var auth = require('./lib/authentication');
auth.authenticate_user(req.body.user, function (user) {
if (user){
req.session.user = user;
console.log('authenticated');
res.redirect(req.body.redir || '/home');
//next();
} else {
console.log('not authenticated');
res.render('logins/new.jade', {title: 'Login Failed', redir:''})
}
});
});

我的申请中还没有其他的东西，因为它还很年轻。我知道我自己并没有在任何地方破坏会议;我检查了。

我做了一些测试，当我尝试在页面上使用局部变量时，这似乎只是一个问题。例如，这是我的观点home.jade

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

div(data-role="page")
div(data-role="header")
a(href='/logout', data-icon='delete', data-ajax="false") Log out
h1= title
a(href='/account', data-icon='info', data-ajax="false") Account

!= partial('user', user)

each jtl in job_task_lists
div(id=jtl.name, class = 'draggable_item', style='border:2px solid black;')
#{jtl.name} - #{jtl.description}
a(data-icon='plus')

div(data-role="footer")
h3 footer

script(src="/javascripts/home.js")

如果我将用户注释掉部分，则会呈现，否则我会遇到此Converting circular structure to JSON问题。

UPDATE
所以在连接eclipse和v8调试器之后，我一直在逐步完成代码，我知道会话和用户对象的混搭在哪里，

在node_modules/connect/lib/middleware/session/session.js

utils.union最终将用户对象的成员混合到会话中，从而导致循环引用。我只是不确定为什么(诚然可能是我的代码)