MongoMapper EmbeddedDocument edge case involving _root_document

[bricestacey]

I am writing a validation for a MongoMapper embedded document. It looks something like so:

if _root_document.settings.select { |s| s.feature_id == feature_id && s.name == name }.size > 1
  errors.add(:name, 'is not unique')
end

If I then try to test this using valid_attribute like so:

describe Setting do
  before do
    @feature = FactoryGirl.create(:feature)
    @feature.settings << subject
  end

  context 'given a setting with the name limit already exists' do
    before { @feature.settings << FactoryGirl.build(:setting, name: 'limit') }
    it { should_not have_valid(:name).when('limit') }
  end
end

It will fail even though it actually doesn't. The problem seems to stem from how valid_attribute clones the subject and then performs validations. At that point, the feature's embedded settings do not contain a reference to the cloned subject, but to the actual subject and so valid_attribute wrongly believes the setting is valid.

I've worked around this by emulating the behavior of valid_attribute without cloning and it works.

It's an obvious edge-case, not sure if it's worth working around, but wanted to let you know.

[bcardarella]

So there might need to be some adapter for the object cloning to pull in any embedded documents. Now that you brought this up I suspect the same problem will happen with ActiveRecord objects that also have associations that need to be validated against.

[bcardarella]

This should be solved with: 1f526c21be6498c6fe17764960c95a8450e1f492

I have turned off cloning by default and it can be forced by doing:

it { should have_valid(:name).when('Brian').clone }