difference between {key:""} and {key:" "}, json file?

Question

I am trying to implement validation on my express Router, The problem is When i pass {title:""} the express-validator didn't throw error , but when i pass {title:" "} it works .

exports.postValidatorCheck = [
  check("title", "The title must not we empty").isEmpty(),
  check("title", "The Length of the Title should be in greater then 10").isLength({
    min: 10,
    max: 1500
  }),
  function(req, res, next) {
    let errors = validationResult(req);
    console.log(errors);
    if (!errors.isEmpty()) {
      const firstError = errors.errors.map(err => err.msg)[0];
      return res.status(400).json({ error: firstError });
    }
    next();
  }
];

jSON file:

{
"title":"",
"body":"This is a new Post"
} 

No error

JSON file

{
"title":" ",
"body":"This is new post"
}

Error as expected.

Answer 1

Validation should use the negative:

check("title", "The title must not we empty").not().isEmpty()

This will make sure the title is not empty, which is what I think you intended.