fire callbacks only when setting was stored sucessfully

app/models/setting.rb

@@ -155,9 +155,12 @@ class Setting < ActiveRecord::Base
     old_value = setting.value
     setting.value = (v ? v : "")
     Rails.cache.delete(cache_key(name))
-    setting.save
-    fire_callbacks(name, setting.value, old_value)
-    setting.value
+    if setting.save
+      fire_callbacks(name, setting.value, old_value)
+      setting.value
+    else
+      old_value
+    end
   end
 
   # Check whether a setting was defined

spec/models/setting_spec.rb

@@ -108,6 +108,12 @@ describe Setting do
       expect(collector).to_not be_empty
     end
 
+    it "calls no callback on invalid setting" do
+      Setting.any_instance.stub(:valid?).and_return(false)
+      Setting.notified_events = 'invalid'
+      expect(collector).to be_empty
+    end
+
     it "calls multiple callbacks when a setting is set" do
       Setting.notified_events = [:some_event]
       Setting.notified_events = [:some_event]