How can I check if field is a valid Email Address OR a valid Username

[nikas-belogolov]

I want to check if a field is a valid email address OR if it's a valid username.

This is how I would do it normally in javascript:

if (value === undefined) return false; // Check if value is undefined. If it is, return false.
if (isEmail(value)) return true; // If value isn't undefined, then check if it's a valid email address.
if (value.match(/^[a-z0-9]+$/i)) return true; // If value isn't an email, then it's got to be a username.
return false; // If value isn't an email address and not a username, then it's an invalid value.

How can I do the same in express-validator?

Note: the field is the same field, "username".

[fedeci]

You can use this middleware:

oneOf([
  body('paramName').exists().isEmail(),
  body('paramName').matches(/*your regex*/),
])

[nikas-belogolov]

it doesn't work, it returns these errors with this input:

input: "Hello@#$%"
errors:

[
  { // Error from invalid username or email address
    value: 'Hello@#$%',
    msg: 'Enter a valid username or email address',
    param: 'username',
    location: 'body'
  },
  { // Error from invalid email
    value: 'Hello@#$%',
    msg: 'Invalid value',
    param: 'username',
    location: 'body'
  }
]

but it should only return one error if the text isn't a username or email address

Heres my code:

oneOf([

    body("username").matches(/^[a-z0-9]+$/i).withMessage((value, { req }) => {
        return req.t("validation:field_valid", { field: req.t("account.username_or_email") });
    }),

    body("username")
        .exists().withMessage((value, { req }) => {
            return req.t("validation:field_required", { field: req.t("account.username_or_email") })
        })
        .isEmail()

    
]

[fedeci]

Hello@#$% is not an email and does not matches the regex you provided😄

---

edit: sorry @anonymous675, I misread your answer. That behavior has already been marked in #956 and will probably be changed in v7.