Rails core - Jul 2006 - Updating a belongs_to foreign key leaves the old association object available

Perhaps this is intentional, but it seems unlikely:

class Person < ActiveRecord::Base
  belongs_to :school
end

p = Person.find(:first)
p.school # nil
p.school_id = School.find_by_name(''High School'').id
p.school.name # High School
p.school_id = School.find_by_name(''Primary School'').id
p.school.name # High School <= Shouldn''t this be Primary School?
p.school.id == p.school_id # false !!!

Of course, p.school(:reload) works fine, but I think it would be nice
for the association accessor to check that the foreign keys match up
and reload the association if they don''t. This should only be
necessary for belongs_to.

A more disturbing example may be something like:

def save
  @person = Person.find(params[:id], :include => :school)
  @person.update_attributes(params[:person])

  # @person.school will refer to the old school, even if a new
school_id was passed in the params
end

Thoughts?

-Jonathan.

> p = Person.find(:first)
> p.school # nil
> p.school_id = School.find_by_name(''High School'').id
> p.school.name # High School
You should be assigning .school= here.  Why are you working with the id?
> p.school_id = School.find_by_name(''Primary School'').id
> p.school.name # High School <= Shouldn''t this be Primary
School?
> p.school.id == p.school_id # false !!!
Again, the .school_id accessors aren''t really meant for use like this.
I  suppose the accessors could check the ids,  but it seems like a lot
of work for a corner case.   An alternative would be to let the
school_id accessor use school.id  if the proxy''s been loaded.
-- 
Cheers

Koz

Isn''t the standard way of updating relationships like this to have a
select box with name="person[school_id]" which will be updated with
update_attributes, like in the second example?

I''ve attached a patch which fixes the behaviour. I guess school_id
could access school.id, and school_id= would have to set @school nil. It makes
more sense to me to put it in the association accessor,
rather than modifiying the attribute accessors.

-Jonathan.

On 7/31/06, Michael Koziarski <michael@koziarski.com>
wrote:
> Again, the .school_id accessors aren''t really meant for use like
this.
> I  suppose the accessors could check the ids,  but it seems like a lot
> of work for a corner case.   An alternative would be to let the
> school_id accessor use school.id  if the proxy''s been loaded.
> --
> Cheers
>
> Koz

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