Rails - May 2006 - Using ''validates_inclusion_of'' to validate foreign key

I seem to be missing something trying to use
''validates_inclusion_of'' to
validate a foreign key and was hoping some one could piont out my 
mistake?

The problem seems to be that Order.find_all.collect is not returning an 
array that contains the order_id, if I replace it with a hardcoded array 
everything works as expected.

The model:

class OrderItem < ActiveRecord::Base
  validates_inclusion_of :order_id, :in => Order.find_all.collect { 
|order| order.id }
  belongs_to :order
end

The test:

class OrderItemTest < Test::Unit::TestCase
  fixtures :orders, :order_items
  def test_validates_inclusion_of_order_id_in_orders
    orderitem = OrderItem.new(:order_id => 1)
    assert( orderitem.save,
orderitem.errors.full_messages.join(''\n''))
  end
end

The fixture:
first:
  id: 1
  sid: ''ON001''

All of the code can be found at http://metaspot.net/dev/browser/?rev=46


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Michael Greenly wrote:
> The problem seems to be that Order.find_all.collect is not returning an 
> array that contains the order_id, if I replace it with a hardcoded array 
> everything works as expected.
> 
Guess I''ll respond to my own post...

This was most likley a bad idea anyway.  I really don''t want to suck an
entire table index into an array every time I want to create or update a 
new row.  I should of just created a validation that did something like 
this....

 def validate
    begin
      Order.find(self.order_id)
    rescue ActiveRecord::RecordNotFound
      errors.add(:order_id, "invalid foreign key reference")
    end
  end

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You might have difficulty using :in => to achieve that. A custom
validation is probably in order. For performance reasons, it''s
probably worth adding a method to ActiveRecord::Base to select just
the model ids. That will save you from having to instantiate all the
model objects each time the validation occurs.

class ActiveRecord::Base
  def self.ids
    connection.select_values("select #{primary_key} from
#{table_name}").collect(&:to_i)
  end
end

class OrderItem
  belongs_to :order

  def validate
    errors.add_to_base "Invalid order" unless
Order.ids.include?(order_id)
  end
end

-Jonathan

On 5/27/06, Michael Greenly <mgreenly@gmail.com>
wrote:
> I seem to be missing something trying to use
''validates_inclusion_of'' to
> validate a foreign key and was hoping some one could piont out my
> mistake?
>
> The problem seems to be that Order.find_all.collect is not returning an
> array that contains the order_id, if I replace it with a hardcoded array
> everything works as expected.
>
> The model:
>
> class OrderItem < ActiveRecord::Base
>   validates_inclusion_of :order_id, :in => Order.find_all.collect {
> |order| order.id }
>   belongs_to :order
> end
>
> The test:
>
> class OrderItemTest < Test::Unit::TestCase
>   fixtures :orders, :order_items
>   def test_validates_inclusion_of_order_id_in_orders
>     orderitem = OrderItem.new(:order_id => 1)
>     assert( orderitem.save,
orderitem.errors.full_messages.join(''\n''))
>   end
> end
>
> The fixture:
> first:
>   id: 1
>   sid: ''ON001''
>
> All of the code can be found at http://metaspot.net/dev/browser/?rev=46
>
>
> --
> Posted via http://www.ruby-forum.com/.
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> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

That is probably a better approach. Using Order.exists? will make the
code a bit shorter:

errors.add_to_base ''Invalid order'' unless
Order.exists?(order_id)

-Jonathan.
>
>  def validate
>     begin
>       Order.find(self.order_id)
>     rescue ActiveRecord::RecordNotFound
>       errors.add(:order_id, "invalid foreign key reference")
>     end
>   end
>

Jonathan Viney wrote:
> That is probably a better approach. Using Order.exists? will make the
> code a bit shorter:
> 
> errors.add_to_base ''Invalid order'' unless
Order.exists?(order_id)
> 
> -Jonathan.
Much better, it''s starting to look a bit more like ruby... now that
it''s
been expressed in a single line ;)

Thanks

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