Django regex validator message has no effect

Question

I am trying to get it so that the validator tells you \"username must be alphanumeric\". This is my code so far. I have confirmed that it validates at the correct time. The

Answer 1

a validate user name here should contain at least one minuscule letter, one capital letter and one numeric, if i understand your code.
to complete Virendra Rajput answer correct the regex with that:
regex=r'^[a-zA-Z0-9]*$'   start with the r'