class ActiveRecord::Associations::CollectionAssociation

See delete for more info.

@author.books.delete_all(:delete_all)
@author.books.delete_all(:nullify)

Example:

You can force a particular deletion strategy by passing a parameter.

deletion strategy for the association is applied.
if the +:dependent+ value is +:destroy+ then in that case the +:delete_all+
on the associated records. It honors the +:dependent+ option. However
Removes all records from the association without calling callbacks

def delete_all(dependent = nil)
  if dependent && ![:nullify, :delete_all].include?(dependent)
    raise ArgumentError, "Valid values are :nullify or :delete_all"
  end
  dependent = if dependent
    dependent
  elsif options[:dependent] == :destroy
    :delete_all
  else
    options[:dependent]
  end
  delete_or_nullify_all_records(dependent).tap do
    reset
    loaded!
  end
end