Attributes appended in associated view stripped when override:true

Issues
1

Hi,

In our project we are overriding relation associations with custom views.

For several reasons (principally many-to-many associations, and multi-table inheritance) we have lots of intermediary tables, which means our codebase has lots of examples of chained method calls on entities:

user.user_groups.first.group.admin

In the case of many-to-many associations, we do make use of ROM’s through: functionality, but often we need to access attributes that exist on the intermediary table. through: also does not seems to work in the case of belongs_to associations. What we were hoping to do was use views with override: true and select_append the attributes of the intermediary table we want onto the target table. Something roughly along these lines:

class Users < ROM::Relation[:sql]
 schema(infer: true) do
  associations do
     has_many :user_groups
     has_many :groups, override: true, view: for_users
  end
 end
end

class UserGroups < ROM::Relation[:sql]
 schema(infer: true) do
  associations do
     belongs_to :user
     belongs_to :group
  end
 end
end

class Groups < ROM::Relation[:sql]
 schema(infer: true) do
    associations do
	  has_many :user_groups
    end
 end

 def for_users(_assoc, users)
	user_ids = users.pluck(:id)

	join(:user_groups)
	  .where(self[:user_id] => user_ids)
	  .select_append { |user_groups:| user_groups[:admin].as(:admin) }
 end
end

Which would allow for a more succinct:
user.groups.first.admin

The issue we are running into is that attributes that are appended in the view, with
override: true are stripped away. This looks to be intended functionality within ROM to remove the join keys.

We have several questions around this.

Firstly, is there a way that we can select_append within views with override: true that we are missing?

Secondly, if not, are there any plans to add this functionality to future releases of ROM?

Lastly, if the answer to both the above are no, would you be open to pull requests that allow for this?

Thanks in advance,
Charlie