Question

I am using a <form:input> on my jsp. The input field should be editable but not nullable. Is there a way to handle this on the client side? i,e, disable the deletion of the value in the field but keep the field editable.

Answer 1

Disabling deletion would be inconvenient for users. It would be better to check the value when focus leaves the field and show error message if it’s empty. For example, using jQuery:

<form:input id = "f" ... />

.

var f = $("#f");
f.blur(function() {
    if (!f.val()) {
        ... // show error message
    }
});
f.change(function() {
    if (f.val()) {
        ... // hide error message
    }
});