Forum: Ruby on Rails Issue w/ Eager Loading

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Paul T. (Guest)
on 2007-06-12 19:14
Hi,

I have a rails app that uses these models:

class CoreRouter < ActiveRecord::Base
  has_many :ports
end

class Port < ActiveRecord::Base
  belongs_to :core_router
  has_many :addresses
end

class Address < ActiveRecord::Base
  belongs_to :port
end

I have one main list page that shows all CoreRouters, the associated
ports and the associated addresses.  The problem is that I now have over
400 addresses and I'm seeing over 400 queries when I generate this page,
taking about 10 seconds to load.  I thought an answer may be Eager
Loading:

@core_routers = CoreRouter.find(:all, :include => [ :ports, :addresses
])

But that fails:

ActiveRecord::ConfigurationError (Association named 'addresses' was not
found; perhaps you misspelled it?):

I'm assuming this is because the CoreRouter class doesn't have a direct
association with the Address class.

How can I get it to eagerly load the addresses that are associated with
the ports?
Philip H. (Guest)
on 2007-06-12 20:29
(Received via mailing list)
>  has_many :addresses
> Loading:
> association with the Address class.
>
> How can I get it to eagerly load the addresses that are associated with
> the ports?

@core_routers = CoreRouter.find(:all,
:include => {:ports => :addresses})

(it's either that or...)

:include => :ports => :addresses)

I can never remember as well I've never actually done it :)
Rob B. (Guest)
on 2007-06-12 21:21
(Received via mailing list)
On Jun 12, 2007, at 12:41 PM, Philip H. wrote:
>>  has_many :addresses
>> page,
>> was not
> @core_routers = CoreRouter.find(:all,
> :include => {:ports => :addresses})
>
> (it's either that or...)

Yeah, it's that.

and if you need to include a :conditions option when you
have :include's, you need to indicate the table such as
:conditions => [ 'core_routers.installed_on < ? AND ports.in_use = ?',
                  1.year.ago.beginning_of_day.to_s(:db), true ]

-Rob

Rob B.    http://agileconsultingllc.com
removed_email_address@domain.invalid
Paul T. (Guest)
on 2007-06-12 22:16
Philip H. wrote:
>
> @core_routers = CoreRouter.find(:all,
> :include => {:ports => :addresses})
>

That worked great... Dropped my DB time down from about 2 seconds to
less than .5 seconds...
Paul T. (Guest)
on 2007-06-12 22:18
Rob B. wrote:
>
> and if you need to include a :conditions option when you
> have :include's, you need to indicate the table such as
> :conditions => [ 'core_routers.installed_on < ? AND ports.in_use = ?',
>                   1.year.ago.beginning_of_day.to_s(:db), true ]
>

Thanks Rob - I don't need this yet, but might!
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