Merge pull request #16 from mr-raccoon-97/main

Add default events

pybondi/events.py

@@ -0,0 +1,25 @@
+from abc import ABC
+from dataclasses import dataclass
+from pybondi.aggregate import Aggregate
+from pybondi.messagebus import Event
+
+@dataclass
+class Added[T: Aggregate](Event):
+    '''
+    The Added[Aggregate] event is used to signal that the aggregate has been added to a session.
+    '''
+    aggregate: T
+
+@dataclass
+class RolledBack[T: Aggregate](Event):
+    '''
+    The RolledBack[Aggregate] event is used to signal that the aggregate has been rolled back in the session.
+    '''
+    aggregate: T
+
+@dataclass
+class Saved[T: Aggregate](Event):
+    '''
+    The Saved[Aggregate] event is used to signal that the aggregate has been committed in the session.
+    '''
+    aggregate: T

pybondi/messagebus.py

@@ -7,20 +7,21 @@
 
 class Event(ABC):
     """
-    Event is an abstract base class for domain events.
+    An abstract base class for domain events. All events should inherit from this class, otherwise
+    they will not be recognized by the message bus.
     """
 
 class Command(ABC):
     """
-    Command is a class representing a request to perform an action.
+    Command is a class representing a request to perform an action. All commands should inherit from this class.
+    Otherwise, they will not be recognized by the message bus.
     """
     ...
-    @abstractmethod
     def execute(self):
         """
         Executes the command.
         """
-        ...
+        raise NotImplementedError
 
 class Messagebus:
     """

pybondi/session.py

@@ -1,10 +1,11 @@
 from collections import deque
 from typing import Callable
-
+from dataclasses import dataclass
 from pybondi.aggregate import Aggregate
 from pybondi.messagebus import Messagebus, Command, Event
 from pybondi.repository import Repository
 from pybondi.publisher import Publisher
+from pybondi.events import Added, RolledBack, Saved
 
 class Session:
     """
@@ -73,9 +74,12 @@ def dequeue(self) -> Command | Event:
 
     def add(self, aggregate: Aggregate):
         """
-        Adds an aggregate to the repository.
+        Adds an aggregate to the repository. Enqueues an Added event for the aggregate.
+        In case that the aggregate state depends on external resources, the aggregate should
+        bring it's state up to date using a handler for the Added event.
         """
         self.repository.add(aggregate)
+        self.enqueue(Added(aggregate))
 
     def dispatch(self, message: Command | Event):
         """
@@ -115,14 +119,24 @@ def begin(self):
 
     def commit(self):
         """
-        Commits changes from the transaction.
+        Commits changes from the transaction. Dispatches a Saved event for each aggregate
+        for which changes were committed. In case that the aggregate state depends on external
+        resources, it should be updated using a handler for the Saved event.
         """
+        self.run()
+        for aggregate in self.repository.aggregates.values():
+            self.dispatch(Saved(aggregate))
         self.repository.commit(), self.publisher.commit()
 
     def rollback(self):
         """
-        Rolls back changes of the transaction.
+        Rolls back changes of the transaction. Dispatches a RolledBack event for each aggregate
+        for which changes were rolled back. In case that the aggregate state depends on external
+        resources, it should be restored to its previous state using a handler for the RolledBack event.
         """
+        for aggregate in self.repository.aggregates.values():
+            self.dispatch(RolledBack(aggregate))
+        self.queue.clear()
         self.repository.rollback(), self.publisher.rollback()
 
     def close(self):

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pybondi"
-version = "0.3.2"
+version = "1.0.0"
 description = "A lightweight library for creating event driven systems using domain driven design."
 authors = ["Eric Cardozo <[email protected]>"]
 license = "MIT"