提交 3b9d2b8d 编写于 作者: S Sean Griffin

Merge pull request #15987 from jamesprior/patch-2

Update documentation on STI change handling
......@@ -233,6 +233,15 @@ module ActiveRecord #:nodoc:
# 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.
......
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