Operation Callbacks
Last updated 29 October 2016Overview
class Comment::Create < Trailblazer::Operation
include Dispatch
callback :after_save do
on_change :notify!
end
end
Note that you need to include Dispatch into operations that use callbacks.
Composable Interface
Using Operation::callback simply creates a new Disposable::Callback::Group class for you.
class Comment::Create < Trailblazer::Operation
callback :after_save do
# this is a Disposable::Callback::Group class.
end
Successive calls with the same name will extend the group.
class Comment::Create < Trailblazer::Operation
callback :after_save do
on_change :notify!
end
callback :after_save do
on_change :cleanup!
end
Dispatching :after_save will now run #notify!, then #cleanup!.
Note that this also works when inheriting callbacks from a parent operation. You can extend it without changing the parent’s callbacks.
If you prefer keeping callbacks in separate classes, you can do so.
class AfterSave < Disposable::Callback::Group
on_change :notify!
end
Register it using ::callback.
class Comment::Create < Trailblazer::Operation
callback :after_save, AfterSave
As always, the callback can be extended locally.
class Comment::Create < Trailblazer::Operation
callback :after_save, AfterSave do
on_update :cleanup!
end
Since Trailblazer copies the callback group, this will change the callbacks only for this operation.
Custom Callbacks
You can attach any callback object you like to an operation. It will receive the contract in the initializer and has to respond to #call.
class MyCallback
def initialize(contract)
@contract = contract
end
def call(options) # this is {context: operation} normally.
User::Mailer.(@contract.email)
end
end
Use ::callback to register it as a group.
class Comment::Create < Trailblazer::Operation
callback :after_save, MyCallback