Forum: Ruby on Rails Receiving already loaded object from find_by method of ActiveRecord::Associations::CollectionProx

09083d9430ebedc23782f93779657695?d=identicon&s=25 Ryo Yamada (Guest)
on 2014-06-02 14:27
(Received via mailing list)
I have the following models

    class Parent < ActiveRecord::Base
      has_many :children
    end

    class Child < ActiveRecord::Base
     belongs_to :parent
    end

What I want to do is changing a child object by
parent.children.find_or_initialize_by() and modify the child object,
then
save it by parent.save. But the children doens't get saved. Here's the
code.

    # prepare a parent with a child
    p = Parent.new({:name=>'parent'})
    p.children << Child.new({:name => 'child'})
    p.save

    # modify and save child
    p = Parent.first
    c = p.children.find_or_initialize_by({:name=>'child'}) #=> returns
the
child already created above
    c.name = 'new child'
    p.save #=> children aren't saved

I know this is because find_by method always returns a new object rather
than the one already loaded. But it seems more natural to me if the code
above works because the method is invoked through
ActiveRecord::Associations::CollectionProxy. Am I missing anything to
get
this to work? Or are there any reasons that find_by on
ActiveRecord::Associations::CollectionProxy have to work as it currently
does?

(I know I can save the modified child by c.save, but I want to save the
child through parant.save, because I want the errors on child object to
be
referenced by parent.errors.)
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