require 'activerecord' module IsParanoid # Call this in your model to enable all the safety-net goodness # # Example: # # class Android < ActiveRecord::Base # is_paranoid # end # def is_paranoid opts = {} opts[:field] ||= [:deleted_at, Proc.new{Time.now.utc}, nil] class_inheritable_accessor :destroyed_field, :field_destroyed, :field_not_destroyed self.destroyed_field, self.field_destroyed, self.field_not_destroyed = opts[:field] # This is the real magic. All calls made to this model will append # the conditions deleted_at => nil (or whatever your destroyed_field # and field_not_destroyed are). All exceptions require using # exclusive_scope (see self.delete_all, self.count_with_destroyed, # and self.find_with_destroyed defined in the module ClassMethods) default_scope :conditions => {destroyed_field => field_not_destroyed} extend ClassMethods include InstanceMethods end module ClassMethods # Actually delete the model, bypassing the safety net. Because # this method is called internally by Model.delete(id) and on the # delete method in each instance, we don't need to specify those # methods separately def delete_all conditions = nil self.with_exclusive_scope { super conditions } end # Use update_all with an exclusive scope to restore undo the soft-delete. # This bypasses update-related callbacks. # # By default, restores cascade through associations that are belongs_to # :dependent => :destroy and under is_paranoid. You can prevent restoration # of associated models by passing :include_destroyed_dependents => false, # for example: # # Android.restore(:include_destroyed_dependents => false) # # Alternatively you can specify which relationships to restore via :include, # for example: # # Android.restore(:include => [:parts, memories]) # # Please note that specifying :include means you're not using # :include_destroyed_dependents by default, though you can explicitly use # both if you want all has_* relationships and specific belongs_to # relationships, for example # # Android.restore(:include => [:home, :planet], :include_destroyed_dependents => true) def restore(id, options = {}) options.reverse_merge!({:include_destroyed_dependents => true}) unless options[:include] with_exclusive_scope do update_all( "#{destroyed_field} = #{connection.quote(field_not_destroyed)}", "id = #{id}" ) end self.reflect_on_all_associations.each do |association| if association.options[:dependent] == :destroy and association.klass.respond_to?(:restore) dependent_relationship = association.macro.to_s =~ /^has/ if should_restore?(association.name, dependent_relationship, options) if dependent_relationship restore_related(association.klass, association.primary_key_name, id, options) else restore_related( association.klass, association.klass.primary_key, self.first(id).send(association.primary_key_name), options ) end end end end end # find_with_destroyed and other blah_with_destroyed and # blah_destroyed_only methods are defined here def method_missing name, *args, &block if name.to_s =~ /^(.*)(_destroyed_only|_with_destroyed)$/ and self.respond_to?($1) self.extend(Module.new{ if $2 == '_with_destroyed' # Example: # def count_with_destroyed(*args) # self.with_exclusive_scope{ self.send(:count, *args) } # end define_method name do |*args| self.with_exclusive_scope{ self.send($1, *args) } end else # Example: # def count_destroyed_only(*args) # self.with_exclusive_scope do # with_scope({:find => { :conditions => ["#{destroyed_field} IS NOT ?", nil] }}) do # self.send(:count, *args) # end # end # end define_method name do |*args| self.with_exclusive_scope do with_scope({:find => { :conditions => ["#{self.table_name}.#{destroyed_field} IS NOT ?", field_not_destroyed] }}) do self.send($1, *args, &block) end end end end }) self.send(name, *args, &block) else super(name, *args, &block) end end # with_exclusive_scope is used internally by ActiveRecord when preloading # associations. Unfortunately this is problematic for is_paranoid since we # want preloaded is_paranoid items to still be scoped to their deleted conditions. # so we override that here. def with_exclusive_scope(method_scoping = {}, &block) # this is rather hacky, suggestions for improvements appreciated... the idea # is that when the caller includes the method preload_associations, we want # to apply our is_paranoid conditions if caller.any?{|c| c =~ /\d+:in `preload_associations'$/} method_scoping.deep_merge!(:find => {:conditions => {destroyed_field => field_not_destroyed} }) end super method_scoping, &block end protected def should_restore?(association_name, dependent_relationship, options) #:nodoc: ([*options[:include]] || []).include?(association_name) or (options[:include_destroyed_dependents] and dependent_relationship) end def restore_related klass, key_name, id, options #:nodoc: klass.find_destroyed_only(:all, :conditions => ["#{key_name} = ?", id] ).each do |model| model.restore(options) end end end module InstanceMethods def self.included(base) base.class_eval do unless method_defined? :method_missing def method_missing(meth, *args, &block); super; end end alias_method :old_method_missing, :method_missing alias_method :method_missing, :is_paranoid_method_missing end end def is_paranoid_method_missing name, *args, &block # if we're trying for a _____with_destroyed method # and we can respond to the _____ method # and we have an association by the name of _____ if name.to_s =~ /^(.*)(_with_destroyed)$/ and self.respond_to?($1) and (assoc = self.class.reflect_on_all_associations.detect{|a| a.name.to_s == $1}) parent_klass = Object.module_eval("::#{assoc.class_name}", __FILE__, __LINE__) self.class.send( :include, Module.new{ # Example: define_method name do |*args| # def android_with_destroyed parent_klass.first_with_destroyed( # Android.first_with_destroyed( :conditions => { # :conditions => { parent_klass.primary_key => # :id => self.send(assoc.primary_key_name) # self.send(:android_id) } # } ) # ) end # end } ) self.send(name, *args, &block) else old_method_missing(name, *args, &block) end end # Mark the model deleted_at as now. def destroy_without_callbacks self.class.update_all( "#{destroyed_field} = #{self.class.connection.quote(( field_destroyed.respond_to?(:call) ? field_destroyed.call : field_destroyed))}", "id = #{self.id}" ) self end # Override the default destroy to allow us to flag deleted_at. # This preserves the before_destroy and after_destroy callbacks. # Because this is also called internally by Model.destroy_all and # the Model.destroy(id), we don't need to specify those methods # separately. def destroy return false if callback(:before_destroy) == false result = destroy_without_callbacks callback(:after_destroy) self end # Set deleted_at flag on a model to field_not_destroyed, effectively # undoing the soft-deletion. def restore(options = {}) self.class.restore(id, options) self end end end ActiveRecord::Base.send(:extend, IsParanoid)