Remove to many issue using mongoid

I ran into an issue when trying to remove a has_many relationship using mongoid backed models.

The issues comes down to this code:

def _remove_to_many_link(relationship_type, key)
  relation_name = self.class._relationships[relationship_type].relation_name(context: @context)

  @model.public_send(relation_name).delete(key)

  :completed
end

Mongoid defines the delete method on a relationship as follow https://github.com/mongodb/mongoid/blob/v5.1.2/lib/mongoid/relations/referenced/many.rb#L103

I had to override the method definition in my resource like this:

def _remove_to_many_link(relationship_type, key)
  relation_name = self.class._relationships[relationship_type].relation_name(context: @context)
  relationship = @model.public_send(relation_name)
  document = relationship.find(id: key)

  relationship.delete(document)

  :completed
end

Not a huge deal but it would interesting to find a way to abstract how we delete relationships.

Start at _remove_to_many_link and compare its relationship.delete(key) call with Mongoid's referenced-many delete contract. Identify the abstraction boundary for relationship deletion; done means has_many removal works with Mongoid without a resource override while existing relationship behavior remains intact.