class ActiveModel::Serializer

we want to merge a new list of values.
avoids the need to scan through the Array looking for entries every time
a unique list of all of the objects that are already in the Array. This
In order to make this efficient, we store a :unique_values hash containing

of all tags for all comments of the post.
which has_many tags, the top-level :tags key will contain the merged list
content for all of the children. For instance, if a Post has_many comments,
In some cases, an Array of associations is built by merging the associated

def merge_association(hash, key, serializables, unique_values)
  already_serialized = (unique_values[key] ||= {})
  serializable_hashes = (hash[key] ||= [])
  serializables.each do |serializable|
    unless already_serialized.include? serializable.object
      already_serialized[serializable.object] = true
      serializable_hashes << serializable.serializable_hash
    end
  end
end