Routing error in nested resources


#1

I am using nested resources as follows:
map.resources :topics do |topics|
topics.resources :items do |items|
items.resources :attachments
end
end

When I generate a RESTful path for new item in the console:
app.new_topic_item_path(2) then I get correct path as
‘/topics/2/items/new’.

However, for the new attachment I am getting error:
app.new_topic_item_attachment_path(22) gives -
ActionController::RoutingError: new_topic_item_attachment_url failed to
generate from {:action=>“new”, :controller=>“attachments”,
:topic_id=>22}, expected: {:controller=>“attachments”, :action=>“new”},
diff: {:topic_id=>22}

    from

/usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route_set.rb:375:in
raise_named_route_error' from /usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route_set.rb:339:ingenerate’
from
/usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:131:in
rewrite_path' from /usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:110:inrewrite_url’
from
/usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:88:in
rewrite' from /usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/integration.rb:218:inurl_for’
from (eval):17:in `new_topic_item_attachment_path’
from (irb):5.


Why is it failing and how to fix this?
And, why is it generating ‘{:action=>“new”, :controller=>“attachments”,
:topic_id=>22}’ ? Shouldn’t it pass item_id rather than topic_id?

Any clues?

Thanks,
CS.


#2

Carlos S. wrote:

I am using nested resources as follows:
map.resources :topics do |topics|
topics.resources :items do |items|
items.resources :attachments
end
end

When I generate a RESTful path for new item in the console:
app.new_topic_item_path(2) then I get correct path as
‘/topics/2/items/new’.

However, for the new attachment I am getting error:
app.new_topic_item_attachment_path(22) gives -
ActionController::RoutingError: new_topic_item_attachment_url failed to
generate from {:action=>“new”, :controller=>“attachments”,
:topic_id=>22}, expected: {:controller=>“attachments”, :action=>“new”},
diff: {:topic_id=>22}

    from

/usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route_set.rb:375:in
raise_named_route_error' from /usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route_set.rb:339:ingenerate’
from
/usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:131:in
rewrite_path' from /usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:110:inrewrite_url’
from
/usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:88:in
rewrite' from /usr/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/action_controller/integration.rb:218:inurl_for’
from (eval):17:in `new_topic_item_attachment_path’
from (irb):5.


Why is it failing and how to fix this?
And, why is it generating ‘{:action=>“new”, :controller=>“attachments”,
:topic_id=>22}’ ? Shouldn’t it pass item_id rather than topic_id?

Any clues?

Thanks,
CS.

Figured it out:
I did new_topic_item_attachment_path and got an error:
‘‘ActionController::RoutingError: new_agenda_item_attachment_url failed
to generate from {:action=>“new”, :controller=>“attachments”} - you may
have ambiguous routes, or you may need to supply additional parameters
for this route. content_url has the following required parameters:
[“agendas”, :agenda_id, “items”, :item_id, “attachments”, “new”] - are
they all satisfied?’’

So I need to pass both topic and item id. But isn’t item associated with
the topic resource? Why do I need to pass both ids?


#3

Hi Carlos!

Because of the nesting. For example, I recently hacked up a version of
Beast which is nested similarly to yours: Forums with many Topics with
many Posts. Creating a new post has the following resource path: /
forums/:forum_id/topics/:topic_id/posts/new
Even though the topic_id in my case is globally unique, it still needs
the forum_id for that path.

You don’t have to do that, though. You could leave them as non-nested
and then just use associations, i.e. Topics has_many Items

I like nested resources conceptually but they do make url generation a
little confusing.

Just remember to use: “rake routes” liberally so that you always know
what routes are available and how to map them.

:slight_smile:

-Danimal

On Mar 31, 12:27 am, Carlos S. removed_email_address@domain.invalid