为什么我的简单 if 检查，如果用户在那里，在我的 ejs 视图中抛出一个错误。 如果 var 不存在，我指定其他内容，但仍然不起作用

Question

so in my header.ejs I have something very simple:

<% if (user) { %> 
hello
<% } %>

Now anytime I run that I get an error a 500 error, which is strange because I thought that if user didn't exist then it would skip over the {} , but it doesn't seem to.

Views Router

Now in my views router I do router.use(authController.isLoggedIn); which does this code:

exports.isLoggedIn = async (req, res, next) => {
if (req.cookies.jwt) {
try {
  // 1) verify token
  const decoded = await promisify(jwt.verify)(
    req.cookies.jwt,
    process.env.JWT_SECRET
  );

  // 2) Check if user still exists
  const currentUser = await User.findById(decoded.id);
  if (!currentUser) {
    return next();
  }

  // 3) Check if user changed password after the token was issued
  if (currentUser.changedPasswordAfter(decoded.iat)) {
    return next();
  }

  // THERE IS A LOGGED IN USER
  res.locals.user = currentUser;
  return next();
} catch (err) {
  return next();
}
  }

next();
};

So, this would be called (I guess*) before accessing any view because I use it higher up, like a higher line up in the code, than any of the other routes.

Now if I pass in a variable to the header.ejs file like this:

exports.getLogin = async (req, res, next) => {
  res.status(200).render('login', {
    age: 16
  });
};

That works, but I don't understand what I'm doing wrong because my references and source materials seem to be doing it exactly this way (as I described above) yet with mine nothing I do seems to fix it. I'm sorry for asking such a simple question, I really have been researching all around and looking for the answer. I searched stackOverflow, and read the ejs documentation but I can't seem to see the issue.

Answer 1

Have you tried using an else statement just to check if that avoids the error?

<% if (user) { %> 
hello
<% } else {%>
user doesn't exists
<% } %>