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Contents
module Sequel
module Plugins
# Sequel's built in Serialization plugin doesn't check for modification
# of the serialized objects, because it requires an extra deserialization of a potentially
# very large object. This plugin can detect changes in serialized values by
# checking whether the current deserialized value is the same as the original
# deserialized value. This does require deserializing the value twice, but the
# original deserialized value is cached.
#
# == Example
#
# require 'sequel'
# require 'json'
# class User < Sequel::Model
# plugin :serialization, :json, :permissions
# plugin :serialization_modification_detection
# end
# user = User.create(:permissions => {})
# user.permissions[:global] = 'read-only'
# user.save_changes
module SerializationModificationDetection
# Load the serialization plugin automatically.
def self.apply(model)
model.plugin :serialization
end
module InstanceMethods
# Detect which serialized columns have changed.
def changed_columns
cc = super
deserialized_values.each{|c, v| cc << c if !cc.include?(c) && original_deserialized_value(c) != v}
cc
end
private
# Clear the cache of original deserialized values after saving so that it doesn't
# show the column is modified after saving.
def after_save
super
@original_deserialized_values.clear if @original_deserialized_values
end
# Return the original deserialized value of the column, caching it to improve performance.
def original_deserialized_value(column)
(@original_deserialized_values ||= {})[column] ||= deserialize_value(column, self[column])
end
end
end
end
end
Version data entries
10 entries across 10 versions & 1 rubygems