Rails - Aug 2006 - Polymorphic Through Relationships

I''m building a site for a school which has a number of activities and
groups.  Each activity can have a multiple leaders and multiple
participants.  The groups and activities vary widely - some are events, some
are classrooms, some are study groups and some are short-term projects.

Instead of having multiple habtm tables, I thought it would be cleaner to
have a single table called ''participations'' that would look
like:

   - participateable_id
   - participateable_type
   - person_id
   - role_id

The model structure might look like this -

   - class Person;
   - class Event; has_many :instructors; has_many :students;
   - class StudyGroup; has_one :instructor; has_many :students;

I''d love to be able to say @event.students <<
Person.find(params[:id]) and
have a new row created in participations with the correct person and a role
id of 2 (let''s say).  Then when I write @event.instructors <<
Person.find(params[:id])
it would create a new row with the person id and a role id of 1.  Is this
possible using standard rails relationships?

To sum it up, I''m looking for a has_many :through relationship where
the
"through" is a rails-polymorphic table with one field defined by the
relationship (role_id - always the same).

I know how to accomplish this by writing my own methods (which is how I have
it now), but I''d like to know if there is a slick way to do this via
built-in relationships.

Thanks in advance -


--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk
-~----------~----~----~----~------~----~------~--~---

Hi!

I think you will find the answer at Josh Susser''s great blog about it
http://blog.hasmanythrough.com/articles/2006/08/19/magic-join-model-creation
> To sum it up, I''m looking for a has_many :through relationship
where the
> "through" is a rails-polymorphic table with one field defined by
the
> relationship (role_id - always the same). 
Priit


--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk
-~----------~----~----~----~------~----~------~--~---

That looks promising - and only a few days old.  Not bad.

On 8/27/06, priit.tamboom-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<priit.tamboom-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Hi!
>
> I think you will find the answer at Josh Susser''s great blog about
it
>
>
http://blog.hasmanythrough.com/articles/2006/08/19/magic-join-model-creation
>
> > To sum it up, I''m looking for a has_many :through
relationship where the
> > "through" is a rails-polymorphic table with one field
defined by the
> > relationship (role_id - always the same).
>
> Priit
>
>
> >
>

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk
-~----------~----~----~----~------~----~------~--~---