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Call initialize_copy when cloning [#3164 state:resolved]

Cloned AR objects are now instantiated through initialize_copy rather than
new/initialize. This allows AR classes to override initialize_copy in order to
implement deep cloning.

Signed-off-by: Joshua Peek <josh@joshpeek.com>
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1 parent 126f623 commit 6361d4234ca7f7c2dcb98e6ed34187d2933b56d7 @paulgillard paulgillard committed with josh Oct 6, 2009
Showing with 39 additions and 28 deletions.
  1. +38 −27 activerecord/lib/active_record/base.rb
  2. +1 −1 activerecord/test/cases/base_test.rb
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65 activerecord/lib/active_record/base.rb
@@ -2427,6 +2427,29 @@ def initialize(attributes = nil)
result
end
+ # Cloned objects have no id assigned and are treated as new records. Note that this is a "shallow" clone
+ # as it copies the object's attributes only, not its associations. The extent of a "deep" clone is
+ # application specific and is therefore left to the application to implement according to its need.
+ def initialize_copy(other)
+ # Think the assertion which fails if the after_initialize callback goes at the end of the method is wrong. The
+ # deleted clone method called new which therefore called the after_initialize callback. It then went on to copy
+ # over the attributes. But if it's copying the attributes afterwards then it hasn't finished initializing right?
+ # For example in the test suite the topic model's after_initialize method sets the author_email_address to
+ # test@test.com. I would have thought this would mean that all cloned models would have an author email address
+ # of test@test.com. However the test_clone test method seems to test that this is not the case. As a result the
+ # after_initialize callback has to be run *before* the copying of the atrributes rather than afterwards in order
+ # for all tests to pass. This makes no sense to me.
+ callback(:after_initialize) if respond_to_without_attributes?(:after_initialize)
+ cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
+ cloned_attributes.delete(self.class.primary_key)
+ @attributes = cloned_attributes
+ clear_aggregation_cache
+ @attributes_cache = {}
+ @new_record = true
+ ensure_proper_type
+ self.class.send(:scope, :create).each { |att, value| self.send("#{att}=", value) } if self.class.send(:scoped?, :create)
+ end
+
# Returns a String, which Action Pack uses for constructing an URL to this
# object. The default implementation returns this record's id as a String,
# or nil if this record's unsaved.
@@ -2555,19 +2578,6 @@ def destroy
freeze
end
- # Returns a clone of the record that hasn't been assigned an id yet and
- # is treated as a new record. Note that this is a "shallow" clone:
- # it copies the object's attributes only, not its associations.
- # The extent of a "deep" clone is application-specific and is therefore
- # left to the application to implement according to its need.
- def clone
- attrs = clone_attributes(:read_attribute_before_type_cast)
- attrs.delete(self.class.primary_key)
- record = self.class.new
- record.send :instance_variable_set, '@attributes', attrs
- 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, <tt>Client < Company</tt> to do something like render <tt>:partial => @client.becomes(Company)</tt>
@@ -2831,6 +2841,21 @@ def inspect
"#<#{self.class} #{attributes_as_nice_string}>"
end
+ protected
+ def clone_attributes(reader_method = :read_attribute, attributes = {})
+ self.attribute_names.inject(attributes) do |attrs, name|
+ attrs[name] = clone_attribute_value(reader_method, name)
+ attrs
+ end
+ end
+
+ def clone_attribute_value(reader_method, attribute_name)
+ value = send(reader_method, attribute_name)
+ value.duplicable? ? value.clone : value
+ rescue TypeError, NoMethodError
+ value
+ end
+
private
def create_or_update
raise ReadOnlyRecord if readonly?
@@ -3093,20 +3118,6 @@ def object_from_yaml(string)
return string unless string.is_a?(String) && string =~ /^---/
YAML::load(string) rescue string
end
-
- def clone_attributes(reader_method = :read_attribute, attributes = {})
- self.attribute_names.inject(attributes) do |attrs, name|
- attrs[name] = clone_attribute_value(reader_method, name)
- attrs
- end
- end
-
- def clone_attribute_value(reader_method, attribute_name)
- value = send(reader_method, attribute_name)
- value.duplicable? ? value.clone : value
- rescue TypeError, NoMethodError
- value
- end
end
Base.class_eval do
View
2 activerecord/test/cases/base_test.rb
@@ -1352,7 +1352,7 @@ def test_clone
cloned_topic.title["a"] = "c"
assert_equal "b", topic.title["a"]
- #test if attributes set as part of after_initialize are cloned correctly
+ # test if attributes set as part of after_initialize are cloned correctly
assert_equal topic.author_email_address, cloned_topic.author_email_address
# test if saved clone object differs from original

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