Node.js表达会话错误 [英] nodejs express session error

问题描述

我用nodejs编写了一个演示网站.在文件 app.js 中，我使用了 express.session

I wrote a demo website with nodejs. In file app.js I used express.session

情况1:

app.use(express.cookieParser())
app.use(express.session({    secret: "whatever"   }));  
//this code is working 

情况2:

app.use(express.session({    secret: "whatever"   }));   
app.use(express.cookieParser());
//this is not correct

错误日志为:

Express
500 TypeError: Cannot read property 'connect.sid' of undefined
at Object.session [as handle] (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\middleware\session.js:239:32)
at next (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\proto.js:193:15)
at Object.favicon [as handle] (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\middleware\favicon.js:77:7)
at next (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\proto.js:193:15)
at Object.handle (D:\web\nodejs\Weibo\node_modules\express-partials\index.js:94:5)
at next (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\proto.js:193:15)
at Object.expressInit [as handle] (D:\web\nodejs\Weibo\node_modules\express\lib\middleware.js:30:5)
at next (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\proto.js:193:15)
at Object.query [as handle] (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\middleware\query.js:44:5)
at next (D:\web\nodejs\Weibo\node_modules\express\node_modules\connect\lib\proto.js:193:15)

推荐答案

Express中的中间件顺序很重要，因为它们按照您定义它们的顺序执行.在您的情况下， cookieParser 中间件会添加一些 session 中间件所使用的信息.

Middleware order matter in Express, as they are executed in the order you defined them. In your case, the cookieParser middleware adds some information that is used by the session middleware.

您可以查看 connect的文档:

会话数据未保存在cookie本身中，但是使用了cookie，因此我们必须使用cookieParser()session()之前的中间件.

Session data is not saved in the cookie itself, however cookies are used, so we must use the cookieParser() middleware before session().

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