Rails - Jan 2008 - has_many_and_belongs_to preloads all data -> how can I do to not to do it?

Hello,

I have two tables:

      class Person < ActiveRecord::Base
         has_and_belongs_to_many :projects
      end

      class Project < ActiveRecord::Base
         has_and_belongs_to_many :people
      end

Then I want to get people working on a project. I do:

      project_record.people.find_all_by_foobar( foobar )

It works, but it internally loads ALL the people working on the project, not 
only "foobar" people.

It seems that just using "project_record.people" loads everything into
memory.
Is there any workaround how to load only what is really needed? Lets imagine 
there is huge amount of projects and you just want to check if a person works 
on a certain project...

Thank you,
Jan


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On 1/2/08, mig <mig-Cu8T68VxBMo@public.gmane.org>
wrote:
>
> Hello,
>
> I have two tables:
>
>       class Person < ActiveRecord::Base
>          has_and_belongs_to_many :projects
>       end
>
>       class Project < ActiveRecord::Base
>          has_and_belongs_to_many :people
>       end
>
> Then I want to get people working on a project. I do:
>
>       project_record.people.find_all_by_foobar( foobar )
>
> It works, but it internally loads ALL the people working on the project,
not
> only "foobar" people.
>
> It seems that just using "project_record.people" loads everything
into memory.
> Is there any workaround how to load only what is really needed? Lets
imagine
> there is huge amount of projects and you just want to check if a person
works
> on a certain project...
Have you considered something like this?

project = Project.find( 1 )
person = People.find( 1 )
person.projects.include? project


-- 
Greg Donald
http://destiney.com/

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Take a look at
http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

For many-to-many associations, there are no dynamic finder proxy
methods.

Use

  project_record.people.find(:all, :conditions => { :foobar =>
"foobar" })

instead.

On 2 Jan., 21:34, mig <m...-Cu8T68VxBMo@public.gmane.org>
wrote:
> Hello,
>
> I have two tables:
>
>       class Person < ActiveRecord::Base
>          has_and_belongs_to_many :projects
>       end
>
>       class Project < ActiveRecord::Base
>          has_and_belongs_to_many :people
>       end
>
> Then I want to get people working on a project. I do:
>
>       project_record.people.find_all_by_foobar( foobar )
>
> It works, but it internally loads ALL the people working on the project,
not
> only "foobar" people.
>
> It seems that just using "project_record.people" loads everything
into memory.
> Is there any workaround how to load only what is really needed? Lets
imagine
> there is huge amount of projects and you just want to check if a person
works
> on a certain project...
>
> Thank you,
> Jan
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