Rails - May 2007 - how to ignore :type in some cases? (when I don't want STI)

Hi,

I have a model Member containing details such as name, address, phone, etc.  
There are various approval stages for new and changed members so I need a few 
extra models based on member, some can use STI, some I''d prefer not to
use
STI.

MemberMod which stores a modified member in the members table using STI.  This 
is necessary because there are approval stages to a modification. This is 
working fine and the simplified model looks like this:

  class MemberMod < Member
    belongs_to :original_member, :class_name => ''Member'',
      :foreign_key => :original_member_id
  end

I have a few other models that are very similar to MemberMod (such as 
MemberTransfer) which should have no problem using the STI method, 
however ...

I''m now creating a MemberProposal model which needs all the fields of a
Member
and a bunch more.  I was planning to use a member_proposals table for the 
extra details but to store the routine member details in the members table 
(to avoid duplicating it all) - however I need the record in members table to 
be easily recognizable as a "proposed member" not a "member"
- I have issues,
here''s the simplified model:

  class MemberProposal < ActiveRecord::Base
    # most details we store in a member record with type set to MemberProposal
    belongs_to :member 
  end

The issue is that when I try to access models that belong_to member it fails, 
things like:

  member_proposal.member.club
  member_proposal.member.state
  member_proposal.member.country

It fails because it thinks Member is a MemberProposal and not a Member 
(technically I suppose it''s correct).  Is there any way to turn off the
magic
interpretation of member[:type] for this use case or do I need to change my 
scheme entirely?

Thanks
-- 
Fraser Campbell <fraser-Txk5XLRqZ6CsTnJN9+BGXg@public.gmane.org>
Georgetown, Ontario, Canada

--~--~---------~--~----~------------~-------~--~----~
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?hl=en
-~----------~----~----~----~------~----~------~--~---

> I have a model Member containing details such as name, address, phone, etc.
> There are various approval stages for new and changed members so I need a
few
> extra models based on member, some can use STI, some I''d prefer
not to use
> STI.
> It fails because it thinks Member is a MemberProposal and not a Member
> (technically I suppose it''s correct).  Is there any way to turn
off the magic
> interpretation of member[:type] for this use case or do I need to change my
> scheme entirely?
I''d consider re-architecting your design. Creating new member-like
models for members with different approval stages seems clunky to me.
How about simply having Member and ApprovalStage models, so that you
can find members by approval stage?


--~--~---------~--~----~------------~-------~--~----~
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?hl=en
-~----------~----~----~----~------~----~------~--~---

On Tuesday 15 May 2007 08:56:27 Mark Thomas wrote:
> > I have a model Member containing details such as name, address, phone,
> > etc. There are various approval stages for new and changed members so
I
> > need a few extra models based on member, some can use STI, some
I''d
> > prefer not to use STI.
> >
> > It fails because it thinks Member is a MemberProposal and not a Member
> > (technically I suppose it''s correct).  Is there any way to
turn off the
> > magic interpretation of member[:type] for this use case or do I need
to
> > change my scheme entirely?
>
> I''d consider re-architecting your design. Creating new member-like
> models for members with different approval stages seems clunky to me.
> How about simply having Member and ApprovalStage models, so that you
> can find members by approval stage?
First thanks for reply.  Yes, I realized I was going down a very dark road the 
more I thought about this.  STI provides just a little too much magic (I had 
already hacked around it for a few cases).  I think abstract classes are the 
way to go:

* MemberDetails = abstract class (no table) base for all other types of member
* Member = regular member
* MemberProposal = mostly like a member but with some extra detail
* MemberMod = all fields of a member plus pointer to the original member
* MemberTransfer = similar to MemberMod

By using an abstract base class all my validations can be in the single model 
and I can continue to use all of the code I''ve developed without change
(a
nice bonus).

I had wanted to avoid having multiple very similar tables but the more I think 
about it I don''t see a problem with it.

-- 
Fraser Campbell <fraser-Txk5XLRqZ6CsTnJN9+BGXg@public.gmane.org>
Georgetown, Ontario, Canada

--~--~---------~--~----~------------~-------~--~----~
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?hl=en
-~----------~----~----~----~------~----~------~--~---