node.js开发错误——TypeError: Cannot set property 'XXX' of undefined

来源：互联网发布：童谣知乎编辑：程序博客网时间：2024/05/15 01:36

在设置express-session时出现该错误。

原因：中间件app.use(session());放的位置不对。

要把session设置的中间件放在路由控制器之前。

正确位置：

var express = require('express');var path = require('path');var favicon = require('serve-favicon');var logger = require('morgan');var cookieParser = require('cookie-parser');var bodyParser = require('body-parser');var ejs = require('ejs');var session = require('express-session');var MongoStore = require('connect-mongo')(session);var flash = require('connect-flash');var routes = require('./routes/index');var settings = require('./settings');var app = express();// view engine setupapp.set('views', path.join(__dirname, 'views'));app.engine('html',ejs.__express);app.set('view engine', 'html');// uncomment after placing your favicon in /public//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));app.use(logger('dev'));app.use(bodyParser.json());app.use(bodyParser.urlencoded({ extended: false }));app.use(cookieParser());app.use(express.static(path.join(__dirname, 'public')));//sessionapp.use(session({  secret:settings.cookieSecret,            //用来防止篡改cookie  key:settings.db,                        //cookie的名字  cookie:{maxAge:1000*60*60*24*30},       //30天  store: new MongoStore({    db:settings.db,    host:settings.host,    port:settings.port,    url: 'mongodb://localhost/blog'  }),  resave:true,  saveUninitialized:false}));//flashapp.use(flash());//设置flashapp.use(function(req, res, next){  res.locals.error = req.flash('error') || "";  res.locals.success = req.flash('success') || "";  next();});routes(app);// catch 404 and forward to error handlerapp.use(function(req, res, next) {  var err = new Error('Not Found');  err.status = 404;  next(err);});// error handlerapp.use(function(err, req, res, next) {  // set locals, only providing error in development  res.locals.message = err.message;  res.locals.error = req.app.get('env') === 'development' ? err : {};  // render the error page  res.status(err.status || 500);  res.render('error');});module.exports = app;

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