How to provide warnings during validation in ASP.NET MVC?

Question

Sometimes user input is not strictly invalid but can be considered problematic.

For example:

• A user enters a long sentence in a single-line Name<

Answer 1

Just a quick comment on the possible re-submit implementation you mentioned...

For the "did you mean to do this?" validation type, from a user's perspective, having to re-submit a form based off an assumption that they made a mistake could be very annoying. I would only implement this 'pseudo-validation' on the client side with javascript and (hopefully quick) ajax calls if you have to hit the server.

I would also attempt to display the warnings on the input's blur/change events so they show before the user hits submit. Maybe not practical in all situations, but I just thought i'd throw it out there.