问如何通过express将参数username传递给/路由器？

EN

router.post('/login', (req, res)=> {
    var username = req.body.username;
    var password = common.md5(req.body.password + common.MD5_SUFFIX);
    db.query(`SELECT * FROM admin_table WHERE username='${username}'`, (err, data)=> {
        if (err) {
            console.log(err);
            res.status(500).send('database error').end();
        } else {
            if (data.length == 0) {
                res.status(404).send('no this admin').end();
            } else {
                if (data[0].password == password) {
                    req.session['admin_id']=data[0].ID;
                    res.redirect('/');

                } else {
                    res.status(404).send('This password is not incorrect!').end();
                }
            }
        }
    });
});
router.get('/login',(req,res)=>{
    res.render('admin/login.ejs',{layout:'/admin/layout.ejs',title:'Login'});
});
router.get('/',(req,res)=>{
    res.render('admin/index.ejs',{layout:'/admin/layout.ejs',title:'Index',username:username});
});