This project is archived and is in readonly mode.

has_one :through with decorated join model saves incorrectly

#1376

The attached patch is several failing tests that show a problem with using has_one :through with a decorated model.

Models are:


# simplified for readability - see full model in source
class Member < ActiveRecord::Base
  has_one :member_detail
  has_one :organization, :through => :member_detail
end

class MemberDetail < ActiveRecord::Base
  # has additional string field 'extra_data'
  belongs_to :member
  belongs_to :organization
end

class Organization < ActiveRecord::Base
  has_many :member_details
  has_many :members, :through => :member_details
end

The problem appears when you create a member, add a member_detail to it, and then add it to an organization. Either two MemberDetails get created, or one is created without the extra_data field set correctly.

See attached tests for more details - all three currently fail.

add-has-one-through-tests.patch 5.82 KB

Reported by Matt Jones · November 14th, 2008 @ 06:18 PM

Activity

Matt Jones
- Tag changed from 2.2.rc1, bug, edge, has_one_through to 2.2.rc1, bug, edge, has_one_through, patch
Update: Some digging tracked this down to HasOneThroughAssociation#create_through_record; it was always deleting the join model record. The attached patch instead uses update_attributes if the join model already exists, and includes tests.

Two of the tests in the previous patch were removed; adding records to the association from the other side doesn't work correctly. Thus
```
@organization.members << @member
```
will still yield bad behavior - but I'm not sure if it should work. The has_many :through on @organization doesn't know anything about the associations defined on @member. Maybe there needs to be a warning in the docs?
- has_one_through_fix.patch 6.5 KB
November 15th, 2008 @ 07:16 AM
Michael Koziarski
- State changed from new to resolved
Nice find,

Yeah, the inverses of associations don't work anywhere in rails at present. The same is true with a simple has_many /belongs_to.

Ideally we can fix that in 2.3, but depends on people getting the time and motivation

Fixed for 2-2 and master.

November 15th, 2008 @ 05:24 PM