[PATCH] has_one :through through belongs_to associations does not build through record when assigning the has_one record

The above test fails in the block because the association proxy is nil, because
of the following code:

    # 38f1ea8fe267947f4baf832d3b15ee5b83f18f71
    # associations.rb:1364
    if retval.nil? and association_proxy_class == BelongsToAssociation
        association_instance_set(reflection.name, nil)
        return nil
    end

I believe the motivation for the above code was to handle the case exemplified
by the following test:

    # 38f1ea8fe267947f4baf832d3b15ee5b83f18f71
    # belongs_to_associations_test.rb:305
    def test_forgetting_the_load_when_foreign_key_enters_late
        c = Client.new
        assert_nil c.firm_with_basic_id

        c.firm_id = 1
        # sometimes tests on Oracle fail if ORDER BY is not provided therefore add always :order with :first
        assert_equal Firm.find(:first, :order => "id"), c.firm_with_basic_id
    end

In case it's not clear, the patch handles the test_forgetting_the_load_when_foreign_key_enters_late test (as well as the rest of the activerecord test suite, at least in my environment :-).

I'm fairly sure the linked commit actually resolves 5173, and not this bug.

No worries (^_^)

created another ticket in regards to querying a has_one :through through a belongs_to. figured id make it separate since this ticket is about creating the records.

#5512 has_one :through through belongs_to fails on includes() i also have a test appended.

I am not able to reproduce this problem with rails master. This is what I did.

require 'test/unit'
require 'test/unit/assertions'
class Object
  include Test::Unit::Assertions
end


ActiveRecord::Schema.define(:version => 20100511140856) do

  create_table "dashboards", :force => true do |t|
    t.string "name"
  end

  create_table "minivans", :force => true do |t|
    t.string "name"
  end

  create_table "speedometers", :force => true do |t|
    t.string  "name"
    t.integer "minivan_id"
    t.integer "dashboard_id"
  end


end
class Dashboard < ActiveRecord::Base
end

class Minivan < ActiveRecord::Base

  has_one :speedometer
  has_one :dashboard, :through => :speedometer

  def self.lab
    minivan = Minivan.new(:name => 'm1')
    dashboard = Dashboard.create(:name => 'd1')

    minivan.dashboard = dashboard

    assert minivan.speedometer
    assert_equal dashboard, minivan.dashboard
    minivan.save
    assert_equal dashboard, minivan.dashboard
  end

end

class Speedometer < ActiveRecord::Base
  belongs_to :minivan
  belongs_to :dashboard
end

> Minivan.lab does not fail for me.

Ok. The test provided in #5512 has_one :through through belongs_to fails on includes() does fail for me. Looking into it.

Neeraj,

Thank you for looking into this.

Your code above does not test the problem: there, you have a has_one (dashboard)
through a has_one(speedometer).

If you change Minivan so it belongs_to(speedometer), instead of has_one, then
your test will exhibit the same failure.

    [davidjh@nyx ((no branch); ruby-1.9.2-p0)] ~/devel/foss/rails/activerecord
    $ ruby --version
    ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
    [davidjh@nyx ((no branch); ruby-1.9.2-p0)] ~/devel/foss/rails/activerecord
    $ git rev-parse HEAD
    8b2e4fddbf7e9d204579cd87ac72f14bc592d5a5
    [davidjh@nyx ((no branch); ruby-1.9.2-p0)] ~/devel/foss/rails/activerecord

    # cat test/cases/associations/issue_5137.rb
    require 'test/unit'
    require 'test/unit/assertions'
    require 'test/cases/helper'
    class Object
      include Test::Unit::Assertions
    end


    ActiveRecord::Schema.define(:version => 20100511140856) do

      create_table "dashboards", :force => true do |t|
        t.string "name"
      end

      create_table "minivans", :force => true do |t|
        t.string "name"
      end

      create_table "speedometers", :force => true do |t|
        t.string  "name"
        t.integer "minivan_id"
        t.integer "dashboard_id"
      end


    end
    class Dashboard < ActiveRecord::Base
    end

    class Minivan < ActiveRecord::Base

      set_primary_key :minivan_id


      belongs_to :speedometer
      has_one :dashboard, :through => :speedometer

      def self.lab
        minivan = Minivan.new(:name => 'm1')
        dashboard = Dashboard.create(:name => 'd1')

        minivan.dashboard = dashboard

        assert minivan.speedometer
        assert_equal dashboard, minivan.dashboard
        minivan.save
        assert_equal dashboard, minivan.dashboard
      end

    end

    class Speedometer < ActiveRecord::Base
      belongs_to :minivan
      belongs_to :dashboard
    end


    class MinivanTest < ActiveRecord::TestCase
      def test_minivan_lab
        Minivan.lab
      end
    end

    [davidjh@nyx ((no branch); ruby-1.9.2-p0)] ~/devel/foss/rails/activerecord
    $ ruby -I'test' -I'test/connections/native_sqlite3/' -I'.' test/cases/associations/issue_5137.rb
    Using native SQLite3
    -- create_table("dashboards", {:force=>true})
       -> 0.0052s
    -- create_table("minivans", {:force=>true})
       -> 0.0273s
    -- create_table("speedometers", {:force=>true})
       -> 0.0055s
    -- initialize_schema_migrations_table()
       -> 0.0014s
    -- assume_migrated_upto_version(20100511140856, "db/migrate")
       -> 0.0003s
    Loaded suite test/cases/associations/issue_5137
    Started
    E
    Finished in 0.057919 seconds.

      1) Error:
    test_minivan_lab(MinivanTest):
    NoMethodError: undefined method `build' for nil:NilClass
        /home/davidjh/devel/foss/rails/activerecord/lib/active_record/associations/has_one_through_association.rb:27:in `create_through_record'
        /home/davidjh/devel/foss/rails/activerecord/lib/active_record/associations/has_one_through_association.rb:10:in `replace'
        /home/davidjh/devel/foss/rails/activerecord/lib/active_record/associations.rb:1474:in `block in association_accessor_methods'
        test/cases/associations/issue_5137.rb:42:in `lab'
        test/cases/associations/issue_5137.rb:60:in `test_minivan_lab'
        /home/davidjh/.rvm/gems/ruby-1.9.2-p0/gems/mocha-0.9.8/lib/mocha/integration/mini_test/version_131_and_above.rb:26:in `run'
        /home/davidjh/devel/foss/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:35:in `block in run'
        /home/davidjh/devel/foss/rails/activesupport/lib/active_support/callbacks.rb:413:in `_run_setup_callbacks'
        /home/davidjh/devel/foss/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:34:in `run'

    1 tests, 0 assertions, 0 failures, 1 errors, 0 skips

    Test run options: --seed 37085

I have rebased http://github.com/hjdivad/rails/tree/issue-5137 to the current
master, which as of now is 8b2e4fddbf7e9d204579cd87ac72f14bc592d5a5. The diff
remains basically the same, but I have regenerated it again for your
convenience.

Neeraj,

The test for invoking association.reload was to handle the following case,
exhibited in a test in test/cases/associations/belongs_to_association_test.rb.

 def test_forgetting_the_load_when_foreign_key_enters_late
   c = Client.new
   assert_nil c.firm_with_basic_id

   c.firm_id = 1
   # sometimes tests on Oracle fail if ORDER BY is not provided
therefore add always :order with :first
   assert_equal Firm.find(:first, :order => "id"), c.firm_with_basic_id
 end

i.e. if the key changes, reload the association. However, the original logic I
had did not properly handle all cases. I have updated the patch branch with a
better patch that is also hopefully more clear. Attached is the new patch.

I finally got the minivan example failing. However the attached fix is not passing. I am leaving for the long weekend. Will take a look when I come back.

This bug seems to be related to (or possibly a duplicate of) #142 belongs_to association not updated when assigning to foreign key.