Regex to check alphanumeric string in ruby

Question

I am trying to validate strings in ruby. Any string which contains spaces,under scores or any special char should fail validation. The valid string should contain only chars a-z

Answer 1

If you are validating a line:

def validate(string)
  !string.match(/\A[a-zA-Z0-9]*\z/).nil?
end

No need for return on each.