Including associations with dynamic conditions

[Vijay Dev]

Given a school model and a student model with the school having a has_many relation to student:

has_many :students, :conditions => proc  { "year_id=#{send(:active_year_id)}" }

where active_year_id is a method defined in the school model, I'm encountering an error that "active_year_id is undefined" when calling:

School.where(:active => true).includes(:students)

The condition works fine when I do, say, School.where(:id => 10).students.

Only when I try to use includes do I get that error. Is that the right behavior. If not, what am I doing wrong and how do I fix ?

Using Rails 3.0.9, REE 1.8.7.

[Frederick Cheung]

Interpolated conditions on associations have never worked with includes, since the point would be to load all students in one go which you can't do in general if each one has different conditions. 

For join based includes I believe this is flat out impossible. For the other form you might be able to crowbar it in, but it feels very tricky

Fred

Using Rails 3.0.9, REE 1.8.7.

--
You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group.
To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-talk/-/9rsY1unEtsEJ.
To post to this group, send email to rubyonra...@googlegroups.com.
To unsubscribe from this group, send email to rubyonrails-ta...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.

[Andrew Skegg]

Vijay Dev <vijaydev.cse@...> writes:

>
>
> Given a school model and a student model with the school having a has_many
relation to student:
>
> has_many :students, :conditions => proc  { "year_id=#{send
(:active_year_id)}" }

That smells like it belongs in a named scope on the School rather than on the
relationship.

[Vijayakumar D]

I want school.students to always return students belonging to the active year. I chose this way so that I don't need to change too much of code.

 

--
You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group.

[Ajit]

I think you can do this:


School.includes(:students).where({ :school => {:active => true, :id =>
10})

let me know if it work.

Ajit

[Andrew Skegg]

Vijayakumar D <vijaydev.cse@...> writes:

>
>
> On Thu, Jul 14, 2011 at 5:53 AM, Andrew Skegg <andrewskegg-
BUHhN...@public.gmane.org> wrote:

>
> Vijay Dev <vijaydev.cse <at> ...> writes:
> >
> >
> > Given a school model and a student model with the school having a has_many
> relation to student:
> >
> > has_many :students, :conditions => proc  { "year_id=#{send
> (:active_year_id)}" }
> That smells like it belongs in a named scope on the School rather than on the
> relationship.
>
>
> I want school.students to always return students belonging to the active
year. I chose this way so that I don't need to change too much of code.

If my ESP is working, given:

School << ActiveRecord::Base
has_many :students
belongs_to :year
end

Student << ActiveRecord::Base
belongs_to :school
belongs_to :year
end

Year << ActiveRecord::Base
has_many :schools
has_many :students
end

then finding students belonging to a particular year should be easy:

School.first.year.students

or closer to your example:

School.find(10).year.students