Rails - Jan 2006 - using "find" when you have 2 has_many relations

An Account has_many Websites which in turn has_many WebsiteDomains

Now I can of course do this:
@domains = Account.find(1).websites.find(1).website_domains.find(:all)
To get all the domains for Account with id 1 and Website with id 1.

I would like to do something like this though:
@domains = 
Account.find(1).websites.find(:all).website_domains.find(:all)
IE, get ALL domains for all websites in Account 1
The code above doesn''t work because of the multiple find(:all)

I could do it using :joins and :conditions I guess but then I lose other 
useful stuff like attributes matching column names in the database.

Any ideas?

-- 
Posted via http://www.ruby-forum.com/.

@domains = Domain.find(:all, :conditions => ["websites.id = ? AND
websites.account_id = ?", website_id, acount_id], :include =>
"website")

Should do it. May need to be tweaked a little.

-Nick

On 1/17/06, Per Djurner <per.djurner@gmail.com>
wrote:
>
> An Account has_many Websites which in turn has_many WebsiteDomains
>
> Now I can of course do this:
> @domains = Account.find(1).websites.find(1).website_domains.find(:all)
> To get all the domains for Account with id 1 and Website with id 1.
>
> I would like to do something like this though:
> @domains >
Account.find(1).websites.find(:all).website_domains.find(:all)
> IE, get ALL domains for all websites in Account 1
> The code above doesn''t work because of the multiple find(:all)
>
> I could do it using :joins and :conditions I guess but then I lose other
> useful stuff like attributes matching column names in the database.
>
> Any ideas?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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<warning type="noob answer">

@account = Account.find(1)
@domains = []
@account.websites.each { |w| @domains << w.website_domains }
@domains.flatten!

</warning>

I hope this is on the right track.  It just seems like you want to 
let ActiveRecord do the work since you''ve gone to the trouble to 
define the relations.

-Rob

At 1/17/2006 10:08 AM, Nick Stuart wrote:
>@domains = Domain.find(:all, :conditions => 
>["<http://websites.id>websites.id = ? AND websites.account_id =
?",
>website_id, acount_id], :include => "website")
>
>Should do it. May need to be tweaked a little.
>
>-Nick
>
>On 1/17/06, Per Djurner 
><<mailto:per.djurner@gmail.com>per.djurner@gmail.com> wrote:
>An Account has_many Websites which in turn has_many WebsiteDomains
>
>Now I can of course do this:
>@domains = Account.find(1).websites.find(1).website_domains.find(:all)
>To get all the domains for Account with id 1 and Website with id 1.
>
>I would like to do something like this though:
>@domains >Account.find(1).websites.find(:all).website_domains.find(:all)
>IE, get ALL domains for all websites in Account 1
>The code above doesn''t work because of the multiple find(:all)
>
>I could do it using :joins and :conditions I guess but then I lose other
>useful stuff like attributes matching column names in the database.
>
>Any ideas?
>
>--
>Posted via <http://www.ruby-forum.com/>http://www.ruby-forum.com/.
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Oops, I forgot that I actually had one more relation that has to go in 
there.
Watcher belongs_to WebsiteDomain.

So what I really would like to do is something like this:

@watcher = Watcher.find(:all, :conditions => [websites.account_id = ?", 
acount_id], :include => ["website_domain", "website"])

This does not work however and I just found this on the RoR API site:
"It?s currently not possible to use eager loading on multiple 
associations from the same table."

Is that why I can not do this?

If so, any work-arounds for it?

-- 
Posted via http://www.ruby-forum.com/.

I guess it comes down to what you are looking for in the final results.
Whats the end goal? A list of domains per watcher? per website? per account?
Need some more info to be able to refine it a bit more.

-Nick

On 1/17/06, Per Dj <per.djurner@gmail.com> wrote:
>
> Oops, I forgot that I actually had one more relation that has to go in
> there.
> Watcher belongs_to WebsiteDomain.
>
> So what I really would like to do is something like this:
>
> @watcher = Watcher.find(:all, :conditions => [websites.account_id =
?",
> acount_id], :include => ["website_domain",
"website"])
>
> This does not work however and I just found this on the RoR API site:
> "It''s currently not possible to use eager loading on multiple
> associations from the same table."
>
> Is that why I can not do this?
>
> If so, any work-arounds for it?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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The goal is to get all Watchers for one Account.
So my main problem is that since I have so many relations (Account --> 
Websites --> WebsiteDomains --> Watchers) in between those two
I''m not
sure how to code it in any elegant way.

Thanks for your help, really appreciate it!

-- 
Posted via http://www.ruby-forum.com/.

On 1/17/06, Per Dj <per.djurner@gmail.com> wrote:
> Oops, I forgot that I actually had one more relation that has to go in
> there.
> Watcher belongs_to WebsiteDomain.
>
> So what I really would like to do is something like this:
>
> @watcher = Watcher.find(:all, :conditions => [websites.account_id =
?",
> acount_id], :include => ["website_domain",
"website"])
>
> This does not work however and I just found this on the RoR API site:
> "It''s currently not possible to use eager loading on multiple
> associations from the same table."
>
> Is that why I can not do this?
Because Rails wasn''t designed with it in mind (it doesn''t
alias tables
in the SQL), and patches to implement it have been rejected (see
http://dev.rubyonrails.org/ticket/1562).
> If so, any work-arounds for it?
There''s the Allow Multiple Associations Same Table plugin:
http://wiki.rubyonrails.org/rails/pages/Allow+Multiple+Associations+Same+Table+Plugin,
which is a conversion of the latest patch in the ticket mentioned
above.

That''s a surprise :O
Thanks for the info.

So if I want to avoid plugins and engines etc then my only choice is to 
raw sql with find_by_sql ?

-- 
Posted via http://www.ruby-forum.com/.

Looks to be the easiest way yes, but its not to painful is it?

Watcher.find_by_sql(["SELECT w.* FROM watchers w LEFT JOIN
website_domains ON website_domains.id = w.website_domain_id LEFT JOIN
websites ON websites.id = website_domains.website_id WHERE
websites.account_id = ?", account_id])

Should do it if I got the table/column names right...

On 1/17/06, Per Dj <per.djurner@gmail.com> wrote:
> That''s a surprise :O
> Thanks for the info.
>
> So if I want to avoid plugins and engines etc then my only choice is to
> raw sql with find_by_sql ?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

> Looks to be the easiest way yes, but its not to painful is it?
No, not too painful :)
Thanks for your help!

-- 
Posted via http://www.ruby-forum.com/.