Javascript 如果会话不可用，则重定向node.js

我正在尝试为我的路由编写代码，如果session.user_id未定义，将重定向回主页。由于某些原因，重定向无法执行，mysql条件被触发，服务器崩溃，因为session.user_id未定义，并且没有该数据无法加载游戏

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });

是否有一种方法可以在所有路由上使用通用重定向，如果会话不可用，则重定向回登录

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });

---

我假设值是

未定义的

，而不是

“未定义的”

（这是一个包含单词“未定义”的字符串）：

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });

您应该使用：

if（req.session.user\u id==未定义）

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });

或

if（type of req.session.user\u id==“未定义”）

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });

除此之外，通常最好有一个检查用户会话的中间件功能。这样，您就可以在所有路由中插入对该中间件的调用，这需要用户登录：

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });

router.get('/game', checkUserSession, function(req,res) {
  // Your code here
});

function checkUserSession( req, res, next )
{
    if( req.session.user_id )
    {
        next();
    }
    else
    {
        res.redirect('/homepage');
    }
}//checkUserSession()

添加一个函数来处理身份验证检查，然后向路由器注入中间件

                router.get('/game', function(req,res) {

                console.log(req.session.user_id);

                if (req.session.user_id === "undefined") {

                res.redirect('/');

                }else {

                var condition = 'userId = ' + req.session.user_id;

                projectX.allGameData(condition, function(data){

                var hbsObject = {heroes : data, logged_in: req.session.logged_in, isUser: req.session.isUser, isAdmin: req.session.isAdmin}

                res.render('game', hbsObject);

                });

                };

                });