为什么我的 API 中的这个端点返回 [] 而不是 404 错误？

Question

I'm currently creating some API with Zeit Now, and I was trying to implement 404 error when the user variable is [] (an empty array), but when I fetch this endpoint, API is sending [] aswell. How can I implement it? Is it because the user is a promise?

const db = require('../../lib/db')
const escape = require('sql-template-strings')

module.exports = async (req, res) => {
  const user = await db.query(escape`
    SELECT *
    FROM users
    WHERE username = ${req.body.username}
    AND password = ${req.body.password}
  `)

  if (user === []) {
    res.status(404).json({ message: 'User with these credentials doesn\'t exist.' })
    return false
  }

  res.status(200).json(user)
}

Answer 1

Because

[] === [] // false

So you want to check the length property

if (user.length === 0) {
    res.status(404).json({ message: 'User with these credentials doesn\'t exist.' })
    return false
}