Limit the char size of an input text field based upon the datatype it's representing

Question

I'm trying to find a better way to validate a text input field that limits it's character input size relative to the datatype linked to. There's no way of matching them (meaning this control is a view of the following DT field and syncs/validates according to it's type), asking a bit much perhaps! 
 But now we got lots of inputs that needs to be limited (when creating a text field by default it isn't, but when creating a varchar in the DB it is to 255 thus creating potential bugs if entering/saving into the DT more than 255 chars through that text field). 
 I though about having a default expression that validates for such and is called upon the validation property of each text field. But having such validations that forces to go back to the server on so many fields is quite heavy for the user experience (each field typing in, pressing TAB, watching the "working" on top of the page and so on). 
 
 Isn't there a way to mask (and thus force an equivalent on the client side only)? 
 Or any other ideas? Must be missing something obvious. 
 
 Thanks!

Jacob Grafenstein · Accepted Answer

I don't know of any way to automatically validate based on the size of the datatype. However, a simple way to achieve this type of validation is to create a rule that takes in the field to validate and max number of characters of the datatype (you can store it as a constant). Then in the rule, return a validation error if len(field) > max number of characters.

Josh · Answer

One way to improve user experience is to validate the field lengths on form submit. It is definitely not as elegant as validating on the field level, but would prevent the fields from validating after the field refreshes.