Question

I want to check before saving event so I can throw an alert everytime a specific field gets updated.
I tried to use “changed” to detect it but update_attributes shortcut the db validation so there is no way for me to use changed?

For example this notices the change:

m = Player.new
m.name = "Tom"
m.changed?  
=> true  

But this does not:

m = Player.new
m.update_attributes!(name: "John")
m.changed?  
=> false

Any ideas how I can do this differently?

Answer 1

changed? returns true if there is non-persisted changes on your object. After your call, the object is up to date — hence the false return. Check the ActiveModel::Dirty module, there is several utilities in it to deal with changes on object. previous_changes could do the trick, and maybe there is a more suited method to your use case.