Question

I’m trying to create a regex for correct username validation in Ruby on Rails but for some reason I am doing something incorrect where all username inputs are invalid. I am allowing for upper-case characters, lower-case characters, numbers, and underscores.

Ruby on Rails name validation regex code:

validates :name, :format => {:with => /\A[A-Za-z\d_]\z/}

What am I doing wrong?

Thanks

Answer 1

# \A[A-Za-z\d_]\z
# 
# Options: ^ and $ match at line breaks
# 
# Assert position at the beginning of the string «\A»
# Match a single character present in the list below «[A-Za-z\d_]»
#    A character in the range between “A” and “Z” «A-Z»
#    A character in the range between “a” and “z” «a-z»
#    A single digit 0..9 «\d»
#    The character “_” «_»
# Assert position at the very end of the string «\z»

This is your expression. Do you really want to match a single character?

I believe that :

/^\w+$/

this is what you are looking for. \w is a shorthand character class for what you have written. The above regex will match a string which consists only of A-Za-Z0-9_