为什么在从 JSON POST 请求中检索到 email 的查询时，Knex (PostgreSQL) 查询总是返回空的 object？

Question

I am trying to build my first react app. In the front end, to sign/log in, when a registered user submits his/her email and correct password, in my server side code for response, a query is done by the retrieved email in PostgreSQL database.

Signin component code:

const handleSignin = (req, res, db, bcrypt) => {
const { email, password } = req.body;
if (!email || !password) {
  return res.status(400).json('incorrect form submission');
}

/*** There are 2 tables: users & login **/
/*** START (code for debugging) ***/
console.log("email retrieved from req: ", email);
console.log("length of email retrieved from req: ", email.length);
const check = "tithi@gmail.com";
console.log("length of hard-coded email, check: ", check.length);
db.select('name', 'email').from('users')
      .where('email', '=', email)
      .then(user => {
          console.log("query by email retrieved from req: ", user[0]);
      })
db.select('name', 'email').from('users')
      .where('email', '=', check)
      .then(user => {
          console.log("query by email(check): ", user[0]);
      })
/*** END (code for debugging) ***/

/*** You can ignore this part ***/
db.select('email', 'hash').from('login')
  .where('email', '=',  email)
  .then(data => {
    const isValid = bcrypt.compareSync(password, data[0].hash);
    if (isValid) {
      return db.select('*').from('users')
        .where('email', '=', email)
        .then(user => {
          res.json(user[0])
        })
        .catch(err => res.status(400).json('unable to get user'))
    } else {
      res.status(400).json('wrong password')
    }
  })
  .catch(err => res.status(400).json('wrong email'))
}

module.exports = {
  handleSignin: handleSignin
}

I used Knex here. The query always returns an empty object. I've checked, the user with this email exists in database. But query by other attributes or even, an email assigned inside the code works.

output:

email retrieved from req:  tithi@gamil.com
length of email retrieved from req:  15
length of hard-coded email, check:  15
query by email retrieved from req:  undefined
query by email(check):  { name: 'tithi', email: 'tithi@gmail.com' }

The email is retrieved correctly that is shown in the console output image. Another problem is, query by email works right when I input these via front end, running on my localhost. But query always returns empty object while I POST via Postman application or the back end deployed on Heroku.

Answer 1

The reason you don't see results when sending the request via Postman is that you're sending the string tithi@gamil.com , which is not contained in your database. Fix the typo and you should see results.