forked from jodosha/vestal_versions
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reversion.rb
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/
reversion.rb
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module VestalVersions
# Enables versioned ActiveRecord::Base instances to revert to a previously saved version.
module Reversion
extend ActiveSupport::Concern
# Provides the base instance methods required to revert a versioned instance.
# Returns the current version number for the versioned object.
def version
@version ||= last_version
end
# Accepts a value corresponding to a specific version record, builds a history of changes
# between that version and the current version, and then iterates over that history updating
# the object's attributes until the it's reverted to its prior state.
#
# The single argument should adhere to one of the formats as documented in the +at+ method of
# VestalVersions::Versions.
#
# After the object is reverted to the target version, it is not saved. In order to save the
# object after the reversion, use the +revert_to!+ method.
#
# The version number of the object will reflect whatever version has been reverted to, and
# the return value of the +revert_to+ method is also the target version number.
def revert_to(value)
to_number = versions.number_at(value)
changes_between(version, to_number).each do |attribute, change|
write_attribute(attribute, change.last)
end
reset_version(to_number)
end
# Behaves similarly to the +revert_to+ method except that it automatically saves the record
# after the reversion. The return value is the success of the save.
def revert_to!(value)
revert_to(value)
reset_version if saved = save
saved
end
# Returns a boolean specifying whether the object has been reverted to a previous version or
# if the object represents the latest version in the version history.
def reverted?
version != last_version
end
private
# Mixes in the reverted_from value if it is currently within a revert
def version_attributes
attributes = super
if @reverted_from.nil?
attributes
else
attributes.merge(:reverted_from => @reverted_from)
end
end
# Returns the number of the last created version in the object's version history.
#
# If no associated versions exist, the object is considered at version 1.
def last_version
@last_version ||= versions.maximum(:number) || 1
end
# Clears the cached version number instance variables so that they can be recalculated.
# Useful after a new version is created.
def reset_version(version = nil)
if version.nil?
@last_version = nil
@reverted_from = nil
else
@reverted_from = version
end
@version = version
end
end
end