Support nested children in Arel::Nodes::And

[ciihla]

Fixes #925.
Fixes #1240.

[scarroll32]

This looks great but do we have test coverage?

[deivid-rodriguez]

Nope, also I tried to reproduce the issue and couldn't.

[scarroll32]

@ciihla thank you for this contribution, is it possible to add a test (that would fail first without your PR) ?

[ciihla]

@ciihla thank you for this contribution, is it possible to add a test (that would fail first without your PR) ?

The test is very specific, maybe it has to do something with combination of multitenancy(acts_as_tenant) + postgres_ext-serializers + our specific usage (hierarchy sql condition). but basically our test fails within this:

let!(:column) { create(:column, space: space) }
    let!(:column2) { create(:column, space: space) }
    let!(:column_value) { create(:column_value, space: space, feature: feature_1, column: column) }
    let!(:column_value2) { create(:column_value, space: space, feature: feature_2, column: column2) }

    let(:params) { { q: { column_values_column_id_not_eq: column.id, id_in: [feature_1.id, feature_2.id] } } }

    it 'returns all data' do
      expect(space.features
                      .select('features.*, case when count(childs.id) > 0 then true else false end as has_children')
                      .joins('left join features childs on childs.parent_id = features.id')
                      .group('features.id').ransack(params[:q]).result.to_a.count).to eq(1)
    end

error:

  NoMethodError:
       undefined method `children' for nil:NilClass
     # /Users/jan.uhlar/.rvm/gems/ruby-3.0.3@pb-backend/gems/ransack-2.5.0/lib/ransack/adapters/active_record/context.rb:146:in `block in remove_association'
     # /Users/jan.uhlar/.rvm/gems/ruby-3.0.3@pb-backend/gems/ransack-2.5.0/lib/ransack/adapters/active_record/context.rb:145:in `delete_if'
     # /Users/jan.uhlar/.rvm/gems/ruby-3.0.3@pb-backend/gems/ransack-2.5.0/lib/ransack/adapters/active_record/context.rb:145:in `remove_association'
     # /Users/jan.uhlar/.rvm/gems/ruby-3.0.3@pb-backend/gems/ransack-2.5.0/lib/ransack/adapters/active_record/ransack/nodes/condition.rb:10:in `block in arel_predicate'
   

Sorry I dont have much time to elaborate more :(

[deivid-rodriguez]

Thanks @ciihla, it definitely makes sense to me that a third gem is involved here. If you find time to isolate this to a sample app, it'd be great. Even temporarily removing either of these gems from your application to see if the issue still reproduces and further isolate the culprit would be great.

[shannondoah]

We encountered another use case that this patch seems to fix: querying a scoped association where the association model also has a default scope (multiple conditions). Here is a standalone test that exposes the error, and a copy with the patch applied that executes without error.

Here is another example reproducing the failure with a different set of conditions.

[tappleby]

@shannondoah I just ran into this same issue, have you been running this patch in production?