Is it changed?

Rails has some useful methods to check whether an object has changed since first being loaded into memory. Here are some examples:

$ rails console --sandbox

2.1.0 :001 > user = User.find(1)

 => #<User id: 1, name: "Roderick", email: "rod@example.com", created_at: ..., updated_at: ...>

2.1.0 :002 > user.name = 'Jimmy'

 => "Jimmy"

2.1.0 :003 > user.changed?

 => true

2.1.0 :004 > user.changed

 => ["name"]

2.1.0 :005 > user.changes

 => {"name"=>["Roderick", "Jimmy"]}

2.1.0 :006 > user.name_changed?

 => true

2.1.0 :007 > user.email_changed?

 => false

2.1.0 :008 > user.name_was

 => "Roderick"

2.1.0 :009 > user.save

 => true

2.1.0 :010 > user.changed?

 => false

More info here: ActiveModel::Dirty.