Question

I like red exclamation marks from ErrorProvider, and I want to use it to show the user where the problem is. I also have a requirement that my Update button must be disabled if data in form is invalid. I disable/enable Update button on TextChanged events of all text boxes. ErrorProvider should be employed from Validating events of all text boxes.

Now the problem: when entering incorrect data in last text box Update button will still be disabled, but ErrorProvider will not be shown because user had not left the control. What can I do in this case? How to minimize confusion from User, who will surely ask “why is Update disabled, but no exclamation marks anywhere on window”?

Answer 1

You can validate the last textbox (or all) on the TextChanged event. In order to wait for the user entering something worth validating you can:

1. wait for a given minimal number of entered characters before
   enabling validation on TextChanged, or
2. start a timer on TextChanged – and restart it on each TextChanged event – with an interval of, say, 3 seconds, and when this timer fires – and the textbox is not empty – you can do the validation.