Rails - Aug 2005 - updating has_and_belongs_to_many collection join attributes

Hi there,
I would like to know how to update collection join attributes

to add an item to a collection you can do push_with_attriubutes() e.g.
order.products.push_with_attributes(product, :quantity = > 7)

how do you update the quantity attribute in this collection? e.g.
order.products.find(1).join_attributes(:quantity => 9)
where join_attributes() is a fictitous method

Any ideas,
thanks, Ben

*Bump*

Just to expand a little,
order = Order.find(:first) #=> order inspection stuff
order.products[0].quantity #=> 3

order.products[0].quantity = 7 #=> 7
order #=> a whole load of stuff that also shows that quantity is now 7
order.save #=> true
order = Order.find(:first)
order.products #=> shows quantity unchanged

should i give up and 
1) delete all the existing products and then add all of them back with
new quantities
or
2) create a new model object for orders_products
 

On 8/4/05, Ben Stephens
<foolfodder-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hi there,
> I would like to know how to update collection join attributes
> 
> to add an item to a collection you can do push_with_attriubutes() e.g.
> order.products.push_with_attributes(product, :quantity = > 7)
> 
> how do you update the quantity attribute in this collection? e.g.
> order.products.find(1).join_attributes(:quantity => 9)
> where join_attributes() is a fictitous method
> 
> Any ideas,
> thanks, Ben
>

*Bump* and more (i share a similar problem)
> *Bump*
> 
> Just to expand a little,
> order = Order.find(:first) #=> order inspection stuff
> order.products[0].quantity #=> 3
order.products.first.quantity.next! #=> 4
order.products.first.save! #=> true
order.products(true).first.quantity #=> 3

or

order.products.first.update_attributes(:quantity=>4) #=> true
order.products(true).first.quantity #=> 3

AFAIK the only way to do this in AR with only a habtm association would be

aprod = order.products.first
order.products.delete(aprod)
aprod.quantity.next!
order.products << aprod

or, to set up triggers on the DB end that would catch duplicate entry
type stuff an update the attributes

Has anyone already solved updating rich attributes in habtm with a
single hit to the database rather than a delete and insert?

> Has anyone already solved updating rich attributes in habtm with a
> single hit to the database rather than a delete and insert?
If you need to update the attributes,  introduce a model for the
association.  Updates aren''t supported on habtm attributes, nor will
they be for the forseeable future.

-- 
Cheers

Koz

> If you need to update the attributes,  introduce a model for the
> association.  Updates aren''t supported on habtm attributes, nor
will
> they be for the forseeable future.
So would this be the best practice?

class OrdersProducts < ActiveRecord::Base
  def self.increment_quantity!(product)
   
OrdersProducts.update_all(["quantity=?",product.quantity.next!],["order_id=?
and product_id=?",product.order_id,product.id])
  end
end

class Products < ActiveRecord::Base
...
  def increment_quantity!
    if respond_to?(:quantity) && respond_to?(:scheduled_shift_id)
      QualificationsScheduledShifts.increment_quantity!(self)
    else
      #errors
    end
  end
end

> class Products < ActiveRecord::Base
> ...
>   def increment_quantity!
>     if respond_to?(:quantity) && respond_to?(:scheduled_shift_id)
>       QualificationsScheduledShifts.increment_quantity!(self)
>     else
>       #errors
>     end
>   end
> end
Of course... by QualificationsScheduledShifts I do mean OrdersProducts

...

heh