Forwarding between controllers

Hi

I am a little confused - perhaps because of coming at this with a Java
head but..

I am looking for the equivalent of a forward from Java MVC frameworks
whereby the request and it's model data contents can be forwarded to
another controller ?

Required scenario :

- NewsController posts to CommentsController to add a comment.
- If the comment is valid we REDIRECT back to NewsContoller.show, all
good.
- If the comment is invalid we FORWARD back to NewsContoller.show. The
comment (and error msgs) would still be in request scope so that view
can render appropriate hints.

I currently get round this by using redirect_to (in place of a
forward) and sticking the comment in the session. Then, in
NewsController.show i check the session before loading the comment
from the DB. I think this is kinda sucky but I found a DHH post that
said there are no kinda forwards in rails :

http://groups.google.com/group/rubyonrails-talk/browse_frm/thread/e8fd7e7953d2350b/7e101906c5869e59?lnk=gst&q=forward&rnum=3#7e101906c5869e59

How do peeps approach this scenario ?

Thanks

Matt

Yea, I've seen render and thought of this approach.

Things is, I'd need to have an add_comment on all *Controllers that
have comments.

That's why I wanted to (re)use CommentsController.create

Perhaps Rails just isn't meant to work like this ?

Any thoughts ?

Matt

Wai, thanks for the suggestions (and your patience !).

I don't think filters are what I'm after and the validation is already
within my model class (Comment)..

I guess this is coming down to a stylistic thing (and, as I said,
perhaps a hangup from Java MVC) but in my understanding, controllers
are the exposed facade for CRUD style actions. All I am really asking
is why one controller can't use another in the same request scope ?

> - NewsController posts to CommentsController to add a comment.

BTW, is there any particular reason why the NewsController would post to
another Controller instead of a Model?

Badly worded on my part, sorry. What I mean is the HTML form, rendered
by a NewsController.show, POSTs to CommentsController.create (actually
just via "/comments" with a POST and the ActiveResource stuff takes
care of the mapping to CommentsController.create).

The comments form is wrapped up in a partial that I can reuse in any
view (say, Interview). Which would also POST to
CommentsController.create..

The comments model (acts_as_commentable) has the context and the id of
it's creator ([NEWS,1,"a comment","matt"],[NEWS,2,"another comment",
"fred"], [INTERVIEW,1,"great interview","john"]). So thats all well
and good. And, upon a successful creation, CommentsController
redirects back to it's caller (News or Interviews). It's just when not
successful, I'd like to FORWARD back to the caller without new request
scope or session munging.

Perhaps the code may help (CommentsController.create):

Grrr - google groups keeps erroring !

Already tried to reply to this, here we go again.

I just realize I misinterpretated what you want to do in the create
method. You can use

render :controller => @comment.commentable_type,
:action => @comment.commentable_id

to render the page without going out of the request scope, until the
comment is valid (then use redirect_to).

"render" doesn't take a :controller symbol so it looks like I am stuck
with a "redirect" and chaining the Comment model into the session for
now..

AFAIK "render" only works for actions within the current controller.
Yes you can use partial templates but that's a different usage.

Thanks anyway..

"render" doesn't take a :controller symbol so it looks like I am stuck
with a "redirect" and chaining the Comment model into the session for
now..

AFAIK "render" only works for actions within the current controller.
Yes you can use partial templates but that's a different usage.

  You want render_component instead, it listens to :controller ... the
documentation says it's slower, tho.

  - Tyler

@Bharat - Got the book next to the laptop :slight_smile: Doesn't cover such a
scenario tho..

Its seems (as I suspected) that this concept just doesn't exist in
Rails, especially considering the DHH response (link in my first
post).

All the methods suggested are about reusing view templates in the
context of the current controller. Yes, I can use "render" and
reference another template but this is in the _context_ of the same
controller (and URL), you'd have to be sure to set up the correct
instance variables for the view also (which required some more dynamic
coding in my case).

My initial workaround is still used in my code and works fine. I'd
just rather not be doing it that way.

I think Rails would rather I just put an "add_comments" entry point in
each controller utilising comments rather than form submitting to the
CommentsController.create. Perhaps, just a stylistic thing..

If I am wrong, I'd love to be told. But please, make sure you
understand this thread !

Cheers

Matt