Disable submit button

Is there a way to disable the submit button if a field on that record is set to a specific value?

I am trying to prevent customers from submitting a new charge for a record which another customer has already submitted a charge for it.

For example, I have a status for each record… PAID or NOT PAID

Whenever a new record is created the status is automatically set to NOT PAID

When a charge is submitted for that record, the status changes to PAID

While I can hide records with PAID statuses from the search results, I am struggling to come up with a solution for an extra layer of protection to prevent new customers submitting a duplicate charge for a record which another customer has already done so.

Unfortunately, hiding records with PAID statues from search results would not be sufficient – as there could be several customers viewing the same record, but only one charge is allowed on a first come, first serve basis.

Ideally, it would be great if I could display a message saying, "Sorry, this service is no longer available."

Hope someone can help.

Many thanks.

Also, based on what you're specifically trying to do, you may want to check out this article: https://support.knack.com/hc/en-us/articles/115001062368-Create-a-Registration-Form-with-Limited-Availability.

Hope this helps!

I was able to do this through CSS. You just have to "inspect" the page to get the view #. For example, this is what worked for me:

#view_824 > form > div > input[type="submit"]:nth-child(5) {

                display: none;


Hi Mike, did you come up with a solution?