Form with subforms

Rails
1

Hi,

I’m looking for a way to implement subforms. For example, a form where
you can add clients, and at the same time enter contactpersons for
this client.

I’ve been looking around, reading ebooks, etc, but can’t seem to find
a good example/tutorial for something like this. So I would be very
thankful if someone could point me in the right direction.

Thanks,

Sven

2

Hi Sven,

Sven Magnus wrote:

I’m looking for a way to implement subforms. For example,
a form where you can add clients, and at the same time enter
contactpersons for this client.

The specs don’t allow for forms within forms. But you can have more
than
one form on a page.

The challenge is to structure things so that the page only submits, from
an
end-user perspective, when you want it to. So you’ll probably end up
with a
mix of form_tag or form_for that submit via HTTP, and other forms that
submit via XMLHttpRequest in the background. Depending how how ‘fancy’
you
want your UI, you’ll probably end up using observers on fields like
checkboxes to trigger the rendering of new forms on the page. I’d
recommend
picking up a copy of Cody F.'s “RJS Tutorial” at O’Reilly. I did
and
found it was $10 well spent.

hth,
Bill

3

Thanks for your reply. I’ll look into it.

Are you talking about “RJS Templates for Rails”?

Thanks,

Sven

4

So, is this approach any good?

  • Store the new “item” in a session variable
  • Create two diffferent forms on the same page, one for adding the
    item and one for adding the subitems using Ajax
  • The subitem form will add new subitems to the item stored in the
    session

Is that how this kind of thing should/coul be done?

Thanks,

Sven

5

Hi Sven,

Sven Magnus wrote:

Are you talking about “RJS Templates for Rails”?

That’s the one. Best $10 I’ve spent so far learning Rails.

Best regards,
Bill

6

You’ll need to be careful using the two forms with an Ajax
implementation on
one. Sometimes a user might have JS off and then will submit in ways you
might not be prepared for.

RSL

7

Hi Sven,

Sven Magnus wrote:

So, is this approach any good?

As Russel notes, you need to recognize that some users may not have js
enabled and deal with that somehow. How you do it really depends on
your
business model. More on that below.

  • Store the new “item” in a session variable

It’s early here and I don’t have a threaded email reader so I don’t know
if
there was something in your previous post that would drive storing the
item
in a session variable. The choice between storing items in session
variables and in the database depends on too many things to give advice
on
without more info.

  • Create two diffferent forms on the same page, one for adding the
    item and one for adding the subitems using Ajax
  • The subitem form will add new subitems to the item stored in the
    session

Is that how this kind of thing should/coul be done?

The general model would be to first render the main form for adding
items.
That form could have an element on it that would trigger the rendering
of
the second form. So maybe there’s a checkbox labeled ‘add sub-items’
next
to an item on the main form. You put an observe_field on that checkbox.
In
your design thinking, you have to figure out how you’re going to handle
the
transaction in both js-enabled and js-disabled states. Here’s one,
still-working-on-my-first-cup-of-java approach.

If the user has js enabled, when they check the checkbox it will trigger
a
method in the controller which uses RJS to render the sub-form
immediately.
So if they’ve got js-enabled they’ll go ahead and add sub-items before
submitting the main form. If the user doesn’t have js enabled, the
observer
won’t do anything. When the main form is submitted, you check the value
of
the checkbox. If it’s checked, you check to see if you have any
sub-items.
If you do, you assume they have js-enabled, that they’re done with that,
and
take them to the next step in the process. If you don’t, you assume
they
have js-disabled and take them to an interim page where they can enter
the
sub-items.

The respond_to method can let you know very early in the user’s visit
whether or not they have js-enabled. This gives you the ability to plan
entirely different ‘routes’ through the app. Or you can take an
approach
like the above. Or you can, depending on your business model, decide
not to
allow the use of the site by js-disabled browsers. All, and more, are
valid
choices. It’s important to make that decision explicitly so you can
communicate it if needed to your visitors.

hth,
Bil

8

Sven Magnus wrote:

Hi,

I’m looking for a way to implement subforms. For example, a form where
you can add clients, and at the same time enter contactpersons for
this client.

I’ve been looking around, reading ebooks, etc, but can’t seem to find
a good example/tutorial for something like this. So I would be very
thankful if someone could point me in the right direction.

Thanks,

Sven

Simple way.

One page, one form…

def client

if contact persons....
   //if any contact persons added
end

end

…and return to the same page.