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Fix observer callbacks firing multiple times on descendant instances

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commit ee491b064bff126a67600d694511986b8636d47b 1 parent 30a0e3f
@kamal kamal authored tenderlove committed
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9 activerecord/lib/active_record/observer.rb
@@ -108,10 +108,17 @@ def add_observer!(klass)
def define_callbacks(klass)
observer = self
+ observer_name = observer.class.name.underscore.gsub('/', '__')
ActiveRecord::Callbacks::CALLBACKS.each do |callback|
next unless respond_to?(callback)
- klass.send(callback){|record| observer.send(callback, record)}
+ callback_meth = :"_notify_#{observer_name}_for_#{callback}"
+ unless klass.respond_to?(callback_meth)
+ klass.send(:define_method, callback_meth) do
+ observer.send(callback, self)
+ end
+ klass.send(callback, callback_meth)
+ end
end
end
end
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14 activerecord/test/cases/lifecycle_test.rb
@@ -7,6 +7,12 @@
class SpecialDeveloper < Developer; end
+class DeveloperObserver < ActiveRecord::Observer
+ def before_save(developer)
+ developer.salary += 1
+ end
+end
+
class SalaryChecker < ActiveRecord::Observer
observe :special_developer
attr_accessor :last_saved
@@ -195,4 +201,12 @@ def test_invalid_observer
assert_equal developer, SalaryChecker.instance.last_saved
end
+ test "callback observing the ancestor does not fire multiple times on descendent" do
+ DeveloperObserver.instance # activate
+ developer = Developer.create! :name => 'Ancestor', :salary => 100000
+ assert_equal 100001, developer.salary, 'ancestor callback fired multiple times'
+ developer = SpecialDeveloper.create! :name => 'Descendent', :salary => 100000
+ assert_equal 100001, developer.salary, 'descendent callback fired multiple times'
+ end
+
end

4 comments on commit ee491b0

@paneq

Why was this fireing twice on descendants ? I think the callbacks are copied right ? Maybe then they should not be copied ?

@tenderlove
Owner

I'm not sure. I'm looking in to it as I don't really like observer code. However, this is a bug so I had to apply. :-(

@paneq

I'm not saying that it was bad to apply, quite contrary, good job on catching and fixing it guys.
Now when we have it working and a proper test is written, we can think about keeping it beautiful :-)

@tenderlove
Owner

Exactly. :-D

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