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Added ActiveRecord::Base#becomes to turn a record into one of another…

… class (mostly relevant for STIs) [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8259 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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commit e6f54290aff2982fe1c295d4b0ac6793a55fa112 1 parent c4cb2dd
@dhh dhh authored
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4 activerecord/CHANGELOG
@@ -1,5 +1,9 @@
*SVN*
+* Added ActiveRecord::Base#becomes to turn a record into one of another class (mostly relevant for STIs) [DHH]. Example:
+
+ render :partial => @client.becomes(Company) # renders companies/company instead of clients/client
+
* Fixed that to_xml should not automatically pass :procs to associations included with :include #10162 [chuyeow]
* Fix documentation typo introduced in [8250]. Closes #10339 [Henrik N]
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14 activerecord/lib/active_record/base.rb
@@ -1806,6 +1806,20 @@ def clone
record
end
+ # Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to
+ # single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record
+ # identification in Action Pack to allow, say, Client < Company to do something like render :partial => @client.becomes(Company)
+ # to render that instance using the companies/company partial instead of clients/client.
+ #
+ # Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either
+ # instance will affect the other.
+ def becomes(klass)
+ returning klass.new do |became|
+ became.instance_variable_set("@attributes", @attributes)
+ became.instance_variable_set("@new_record", new_record?)
+ end
+ end
+
# Updates a single attribute and saves the record. This is especially useful for boolean flags on existing records.
# Note: This method is overwritten by the Validation module that'll make sure that updates made with this method
# aren't subjected to validation checks. Hence, attributes can be updated even if the full object isn't valid.
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7 activerecord/test/base_test.rb
@@ -1737,4 +1737,9 @@ def test_attribute_for_inspect
assert_equal %("#{t.written_on.to_s(:db)}"), t.attribute_for_inspect(:written_on)
assert_equal '"This is some really long content, longer than 50 ch..."', t.attribute_for_inspect(:content)
end
-end
+
+ def test_becomes
+ assert_kind_of Reply, topics(:first).becomes(Reply)
+ assert_equal "The First Topic", topics(:first).becomes(Reply).title
+ end
+end
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