This example shows another variation of the Dog aggregate class used in the tutorial and module docs.
Like in the previous example, this example also does not use the library Aggregate class. Instead, it defines its own Aggregate and DomainEvent base classes. In contrast to the previous examples, the aggregate is defined as frozen dataclasses to be an immutable object. This has implications for the aggregate command methods, which must simply return the events that they trigger without mutating the state of the aggregate object.
The Dog aggregate is an immutable frozen dataclass, but it otherwise similar to the previous example. It explicitly defines event classes. And it explicitly triggers events in command methods. However, it has a mutate() method which evolves aggregate state by constructing a new instance of the aggregate class for each event.
The application code in this example must receive the new events that are triggered when calling the aggregate command methods. The aggregate projector function must also be supplied when getting an aggregate from the repository and when taking snapshots.
../../../eventsourcing/examples/aggregate5/domainmodel.py
../../../eventsourcing/examples/aggregate5/application.py
../../../eventsourcing/examples/aggregate5/test_application.py