[Seaside] action before value changing in forms?

[Avi Bryant]

On Wed, 18 Jun 2003, Ragnar Hojland Espinosa wrote:

> I'd need to be able to execute a method or block before values change
> for the fields of a form.

The simplest thing I can think of is to put a hidden input with a callback
at the beginning of the form.  Something like:

html form: [
  html hiddenInputWithValue: '' callback: [:v | self registerCompany].
  "... rest of the form ..."
]

Since callbacks are evaluated in the order in which they are defined, this
is guaranteed to get executed before any of the other fields get
processed.