Validate: Only letters, numbers and -

Question

Hello,

I would like to validate my users, so they can only use a-z and - in their username.

validates_format_of :username, :with => /[a-z]/

However this rule also allows spaces ._@

Username should use only letters, numbers, spaces, and .-_@ please.

Any ideas?

Best regards. Asbjørn Morell

Answer 1

The [] may contain several "rules" so [a-z0-9] gives lowercase letters and numbers

the special character - must go at the start of the rule

Does

[-a-z0-9@_.]

give the effect you want?

Answer 2

You may need to say the whole string must match:

validates_format_of :username, :with => /^[-a-z]+$/

You may also need to replace ^ with \A and $ with \Z, if you don't want to match a newline at the start/end. (thanks to BaroqueBobcat)

Appending an i will cause it to match in a case-insensitive manner. (thanks to Omar Qureshi).

(I also originally left off the +: thanks to Chuck)

Answer 3

Simply change the regular expression to match all characters your specification states (\w covers all alphanumeric characters -- letters and numbers -- and an underscore).

validates_format_of :username, :with => /[\w \.\-@]+/

Answer 4

validates_format_of :username, :with => /^[\w\-@]*$/

Note the *, which means '0 or more'