How to write a validation for exactly 3 digits in ruby-on-rails?

In my controller I have this :

validates_presence_of :order_of_importance, :on => :create, :with =>开发者_JS百科 /^\d{3}$/

But this would still validate ( i think ), if they typed :

4231

But I want to make sure they only type in 3 digit characters.

Any ideas?

/^\d{3}$/ should do it. It makes sure that the digits start and end at the ends of the string to match.

Also, you don't need the i at the end, since digits aren't cased.

You can try

validates_length_of :order_of_importance, :maximum => 3

A perhaps "more Railsy" way would be:

validates_length_of       :order_of_importance, :on => :create, :is => 3
validates_numericality_of :order_of_importance, :on => :create