An Action is an object which handles the process of calling a UseCase and map the response.
Since the action is basically built on a Usecase to execute it we have to link it to an interaction through ViewModel such as clicking on a button.
When the interaction happens UseCase is executed and the result is mapped and passed to the ViewModel.
Generally an action use only one UseCase but is possible to define an ActionQueue which is a special type of Action which calls multiple UseCases sequentially.
Into an ActionQueue each UseCase, except the first, take the result of the previous as parameters and give the output to the next.
To execute a ActionQueue as for the Action we have to link it to an interaction, but in this case when the interaction happens the first usecase of the sequence is executed and pass its results to the next one, repeating this for each usecase of the sequence, except the last one which return the mapped result to the ViewModel.
An SingleAction is an object which handles the process of calling a UseCase and map the response.
This avoids a common problem with events: on configuration change (like rotation) an update
can be emitted if the observer is active. This LiveData only calls the observable if there's an
explicit call to setValue() or call().
Note that only one observer is going to be notified of changes.
When the interaction happens UseCase is executed and the result is mapped and passed to the ViewModel.
[alt_text] (https://github.com/googlesamples/android-architecture/blob/dev-todo-mvvm-live/todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/SingleLiveEvent.java "SingleLiveEvent")
Below an example of Action
val actionLogin = Action.Builder<ActionParams,Model,UiModel>()
.useCase(LoginUseCase::class.java)
.buildWithUiModel { UiModel(it) }Below an example of ActionQueue
val actionQueue = ActionQueue.Builder<LoginActionParams, UserLogged>()
.setFirstUseCase(FirstUseCase::class.java)
.addUseCase(...)
.setLastUseCase(...)Below an example of SingleAction
val redoOrderAction = SingleAction.Builder<RedoOrderActionParams, RedoOrderActionResult, RedoOrderActionResult>()
.useCase(redoOrderUsecase)
.buildWithUiModel { it }