Question

Can someone help me write the regular expression for validates_format_of.

It should fail if any one of

< > $ \ any_non_printable_character

is present.

Thanks.

Answer 1

Something like this would work with Ruby 1.9:

/\A[^<>\\$\p{^Print}]*\z/

That will match anything that doesn’t contain your bad characters and hence should work nicely in a validation. That will also match an empty string though so you could use + instead of * or add a length or present? check if you wanted to exclude ''.