# File lib/dm-core/resource.rb, line 147 def key return @_key if defined?(@_key) model_key = model.key(repository_name) key = model_key.map do |property| original_attributes[property] || (property.loaded?(self) ? property.get!(self) : nil) end # only memoize a valid key @_key = key if model_key.valid?(key) end