Validation performed on has_many associations before updatin


I have a Campaign model which has_many :condition_sets. The ConditionSet
belongs_to :campaign and also validates_presence_of :campaign_id

Now, If I…

c =
s =!
ActiveRecord::RecordInvalid: Validation failed: Condition sets is

=> [“Campaign can’t be blank”]

I’d expect Rails to set the campaign_id foreign key before performing
validation on the ConditionSet, right?

Removing the validates_presence_of :campaign_id lets the campaign save…

c =
s =!
=> #<Campaign id: 1, created_at: “2007-07-13 09:20:08”, updated_at:
“2007-07-13 09:20:08”>

Am I just being dumb???


Ruby version 1.8.6 (i686-darwin8.10.1)
RubyGems version 0.9.4
Rails version 1.2.3
Active Record version 1.15.3
Action Pack version 1.13.3
Action Web Service version 1.2.3
Action Mailer version 1.3.3
Active Support version 1.4.2
Edge Rails revision 436
Application root /Users/ian/Projects/systino/trunk
Environment development
Database adapter mysql
Database schema version 64

Ian L. wrote:

=> [“Campaign can’t be blank”]

I’d expect Rails to set the campaign_id foreign key before performing
validation on the ConditionSet, right?

campaign_id can’t be set before it’s validated because it is unknown
until the campaign is saved, and validation is designed to prevent
anything being saved unless the whole object hierarchy is valid.

The usual solution is:

class ConditionSet
  validates_presence_of :campaign # Checks for valid object or fk
c =
s =
s.campaign = c # Currently not set automatically by Rails!

We develop, watch us RoR, in numbers too big to ignore.

Thanks Mark, it seems pretty obvious now you’ve pointed it out.

I’m having a similar problem with a has_one association this time but
applying what I’ve learned here doesn’t seem to work. To confuse me even
more, the parent has_one association works fine.

Here is some debug of what my app is doing…

BUILD Incentive::ConditionSet#build_promoter
ASSIGN Incentive::ConditionSet#promoter <= Incentive::PromoterCondition
ASSIGN FOREIGN Incentive::PromoterCondition#condition_set <=

BUILD Incentive::PromoterCondition#build_order
ASSIGN Incentive::PromoterCondition#order <= Incentive::OrderCondition
<= Incentive::PromoterCondition

BUILD Incentive::OrderCondition#build_order_value
ASSIGN Incentive::OrderCondition#order_value <=
ASSIGN FOREIGN Incentive::OrderValueCondition#order <=

ConditionSet, PromoterCondition and OrderCondition all save correctly,
however OrderValueCondition fails due to order_id being NULL. The
is the same if I rely on the build_* methods.

So to recap… Campaign has_many ConditionSets has_one PromoterCondition
has_one OrderCondition has_one OrderValueCondition. The only difference
between the PromoterCondition / OrderCondition and OrderCondition /
OrderValueCondition associations is that the PromoterCondition /
OrderCondition is infact a polymorphic one via a OrderConditionable
interface, but surely that shouldn’t be causing the problem?

Today really is a has_many :headaches day!


OK this is odd… or just not what I’m expecting.

class OrderValueCondition
belongs_to :order, :class_name => ‘Incentive::OrderCondition’

Rails should infer order_id as the foreign key, right? I’m not sure what
Rail thinks it is, because when I explicitly specify :foreign_key =>
:order_id it saves.

…the penny drops…

Just noticed:

DEPRECATION WARNING: The inferred foreign_key name will change in
Rails 2.0to use the association name instead of its class name when
they differ.
When using :class_name in belongs_to, use the :foreign_key option to
explicitly set the key name to avoid problems in the transition. See
Ruby on Rails — A web-app framework that includes everything needed to create database-backed web applications according to the Model-View-Controller (MVC) pattern. for details.