diff options
Diffstat (limited to 'activerecord/lib/active_record/inheritance.rb')
| -rw-r--r-- | activerecord/lib/active_record/inheritance.rb | 63 |
1 files changed, 44 insertions, 19 deletions
diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb index da73112e90..fd1e22349b 100644 --- a/activerecord/lib/active_record/inheritance.rb +++ b/activerecord/lib/active_record/inheritance.rb @@ -1,6 +1,37 @@ require 'active_support/core_ext/hash/indifferent_access' module ActiveRecord + # == Single table inheritance + # + # Active Record allows inheritance by storing the name of the class in a column that by + # default is named "type" (can be changed by overwriting <tt>Base.inheritance_column</tt>). + # This means that an inheritance looking like this: + # + # class Company < ActiveRecord::Base; end + # class Firm < Company; end + # class Client < Company; end + # class PriorityClient < Client; end + # + # When you do <tt>Firm.create(name: "37signals")</tt>, this record will be saved in + # the companies table with type = "Firm". You can then fetch this row again using + # <tt>Company.where(name: '37signals').first</tt> and it will return a Firm object. + # + # Be aware that because the type column is an attribute on the record every new + # subclass will instantly be marked as dirty and the type column will be included + # in the list of changed attributes on the record. This is different from non + # STI classes: + # + # Company.new.changed? # => false + # Firm.new.changed? # => true + # Firm.new.changes # => {"type"=>["","Firm"]} + # + # If you don't have a type column defined in your table, single-table inheritance won't + # be triggered. In that case, it'll work just like normal subclasses with no special magic + # for differentiating between them or reloading the right type with find. + # + # Note, all the attributes for all the cases are kept in the same table. Read more: + # http://www.martinfowler.com/eaaCatalog/singleTableInheritance.html + # module Inheritance extend ActiveSupport::Concern @@ -48,16 +79,6 @@ module ActiveRecord :true == (@finder_needs_type_condition ||= descends_from_active_record? ? :false : :true) end - def symbolized_base_class - ActiveSupport::Deprecation.warn("ActiveRecord::Base.symbolized_base_class is deprecated and will be removed without replacement.") - @symbolized_base_class ||= base_class.to_s.to_sym - end - - def symbolized_sti_name - ActiveSupport::Deprecation.warn("ActiveRecord::Base.symbolized_sti_name is deprecated and will be removed without replacement.") - @symbolized_sti_name ||= sti_name.present? ? sti_name.to_sym : symbolized_base_class - end - # Returns the class descending directly from ActiveRecord::Base, or # an abstract class, if any, in the inheritance hierarchy. # @@ -120,14 +141,8 @@ module ActiveRecord candidates << type_name candidates.each do |candidate| - begin - constant = ActiveSupport::Dependencies.constantize(candidate) - return constant if candidate == constant.to_s - # We don't want to swallow NoMethodError < NameError errors - rescue NoMethodError - raise - rescue NameError - end + constant = ActiveSupport::Dependencies.safe_constantize(candidate) + return constant if candidate == constant.to_s end raise NameError.new("uninitialized constant #{candidates.first}", candidates.first) @@ -167,7 +182,7 @@ module ActiveRecord def type_condition(table = arel_table) sti_column = table[inheritance_column] - sti_names = ([self] + descendants).map { |model| model.sti_name } + sti_names = ([self] + descendants).map(&:sti_name) sti_column.in(sti_names) end @@ -195,8 +210,18 @@ module ActiveRecord end end + def initialize_dup(other) + super + ensure_proper_type + end + private + def initialize_internals_callback + super + ensure_proper_type + end + # Sets the attribute used for single table inheritance to this class name if this is not the # ActiveRecord::Base descendant. # Considering the hierarchy Reply < Message < ActiveRecord::Base, this makes it possible to |