This is a pretty generic feature request I suppose. I would like to see some more input validation for form fields. My worst experiences with foreman's forms has been when changing a parameter for a puppet class, for example, adding an extra IP to a firewall puppet class parameter:

{"100 allow some ip":{"source":"123.123.123.123"}}

If you make one mistake in the above value, foreman doesn't notify about the error, then proceeds to save an empty variable instead. I was lucky to have copied the original value to my clipboard so I could go back and re-add the previous value and check it for errors manually.

It would be nice if foreman could be a little bit more forgiving when a user submits a form. If it doesn't know what to do with the data, don't just go ahead and POST to the server, instead inform the user that an invalid parameter was submitted. So why is it generic? Because it counts for pretty much all form fields that a user can send data with. :)