How do you use :on_hide in auto_complete_field?


#1

I’m trying to get some auto_complete_field stuff going, and I have them
working for the most part, but I can’t quite get how the :on_hide option
works. I’m hoping that I can populate a hidden field with the id of the
chosen record with it…is that going to be possible? Thanks for your
help.


#2

toby sterrett <tsterrett@…> writes:

I’m trying to get some auto_complete_field stuff going, and I have them
working for the most part, but I can’t quite get how the :on_hide option
works. I’m hoping that I can populate a hidden field with the id of the
chosen record with it…is that going to be possible?

You give the :on_hide parameter a Javascript fragment that you want to
have
executed on the client (in the browser) at the appropriate time. It can
be any
Javascript you want.

Since your Javascript executes on the client, it has full access to
anything in
the DOM of the page you rendered. . . but (other edge of the sword)
since it’s
on the client, it has NO access to anything in your Rails code (unless,
of
course, your Javascript makes an XmlHttpRequest call back to Rails).
So, if you
want the Javascript to do something with Rails data, you have to make
sure you
either render the data on the page somewhere, or you include it in your
Javascript fragment directly yourself.

You said you want to populate a hidden field with the id of a selected
record;
yes, that should be no problem. I haven’t tested this, but it should be
something like:
:on_hide => “$(‘hiddenField_id’).value = $(‘input_id’).value”

A few points about this:

  • Because Rails includes the Prototype library, you can use
    it’s shorthand $ function to refer to DOM elements by their ID.
  • You have to be careful with your quotes–both Ruby and Javascript
    have their own quoting requirements, and you need to watch out
    you don’t have one step on the other’s toes.
  • Be aware that just because the user selected an item on the
    auto-complete list, that doesn’t mean they’re not going to
    type more characters into input field manually–thus making
    the ID in your hidden field wrong. If you absolutely want the
    hidden field to contain the ID of their selected record, you
    will probably need to do something more sophisticated. (I did
    something like this and ended up using an observe_field helper
    to watch what the user was typing, and then building my own
    version of auto_complete_field that put the auto-complete
    results into a select input, and then using some Javascript to
    copy the id of whichever item in the select input they selected
    into the hidden field. . . that way the hidden field was
    certain to contain the ID of the record they selected).

–Forrest