Rails - Apr 2008 - some help with deleting from the objects with dependencies

Would welcome some advice on this:

I have customers, orders and batches.

Customer has many Orders
Batch has many Orders

Now I want to do a batch delete, that will delete all orders in the
batch and when the orders are deleted, I want to delete any customers
that belong to the order provided they dont belong to any other
orders.

I am thinking that :dependent=>:delete_all  would seem ok for the
orders, but I don''t know how to handle the customers.  My current
thinking is to let the customers become orphaned and then just clean
them up by deleting all customers with 0 orders.  But that feels a bit
loose.

Thanks
Tony
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

There''s likely a better way than this, but to start out I think I
would first create an array of the id''s in customer.orders. Then
delete the batch while cascade deleting the orders. After that
completes successfully then delete the customers from the list you
stored in the array [WHERE customers.id in (x, y, z)].

Also it would be best to do this in a single transaction so that it
can be rolled back in case there are any errors.

Just a thought, but does this relationship make sense to your
application:
Customer has many Batches :dependent => :destroy
Batch has many Orders :dependent => :destroy

I assume it doesn''t, but I wanted to mention it just in case it does.

On Apr 3, 9:54 am, tonypm
<tonypmar...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org>
wrote:
> Would welcome some advice on this:
>
> I have customers, orders and batches.
>
> Customer has many Orders
> Batch has many Orders
>
> Now I want to do a batch delete, that will delete all orders in the
> batch and when the orders are deleted, I want to delete any customers
> that belong to the order provided they dont belong to any other
> orders.
>
> I am thinking that :dependent=>:delete_all  would seem ok for the
> orders, but I don''t know how to handle the customers.  My current
> thinking is to let the customers become orphaned and then just clean
> them up by deleting all customers with 0 orders.  But that feels a bit
> loose.
>
> Thanks
> Tony
--~--~---------~--~----~------------~-------~--~----~
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@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Thanks for the suggestion Robert.

For my purposes I did this in the end

In order.rb

def before_destroy
    customer.destroy  if customer.orders.count == 1
  end

seems to have achieved the desired result.

Tonypm
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---