Improved aggregate examples 7 and 8 by introducing a custom type of v…

…alue object (the Trick class) and using this in aggregate events and aggregate state, and having this type reconstructed from JSON by Pydantic when reconstructing aggregate state from both recorded aggregate events and snapshots which simply contain string values representing the name of the trick.

Makefile

@@ -148,7 +148,7 @@ create_postgres_db:
 .PHONY: updatetools
 updatetools:
 	pip install -U pip
-	pip install -U black mypy flake8 flake8-bugbear isort
+	pip install -U black mypy flake8 flake8-bugbear isort orjson python-coveralls coverage
 
 .PHONY: docs
 docs:

docs/topics/examples/aggregate7.rst

@@ -21,7 +21,8 @@ that have been deserialised by orjson.
 One advantage of using Pydantic here is that any custom value objects
 will be automatically reconstructed without needing to define the
 transcoding classes that would be needed when using the library's
-default ``JSONTranscoder``.
+default ``JSONTranscoder``. This is demonstrated with the ``Trick``
+class.
 
 
 Domain model

docs/topics/examples/aggregate8.rst

@@ -20,7 +20,8 @@ Pydantic model.
 One advantage of using Pydantic here is that any custom value objects
 will be automatically reconstructed without needing to define the
 transcoding classes that would be needed when using the library's
-default ``JSONTranscoder``.
+default ``JSONTranscoder``. This is demonstrated with the ``Trick``
+class.
 
 
 Domain model

eventsourcing/application.py

@@ -884,7 +884,10 @@ def take_snapshot(
             aggregate = self.repository.get(
                 aggregate_id, version=version, projector_func=projector_func
             )
-            snapshot = type(self).snapshot_class.take(aggregate)
+            snapshot_class = getattr(
+                type(aggregate), "Snapshot", type(self).snapshot_class
+            )
+            snapshot = snapshot_class.take(aggregate)
             self.snapshots.put([snapshot])
 
     def notify(self, new_events: List[DomainEventProtocol]) -> None:

eventsourcing/domain.py

@@ -1556,7 +1556,7 @@ def take(cls: Any, aggregate: Any) -> Any:
 
 class CanSnapshotAggregate(HasOriginatorIDVersion, CanCreateTimestamp):
     topic: str
-    state: Dict[str, Any]
+    state: Any
 
     @classmethod
     def take(

eventsourcing/examples/aggregate7/application.py

@@ -4,6 +4,7 @@
 from eventsourcing.application import Application
 from eventsourcing.examples.aggregate7.domainmodel import (
     Snapshot,
+    Trick,
     add_trick,
     project_dog,
     register_dog,
@@ -26,7 +27,7 @@ def register_dog(self, name: str) -> UUID:
 
     def add_trick(self, dog_id: UUID, trick: str) -> None:
         dog = self.repository.get(dog_id, projector_func=project_dog)
-        self.save(add_trick(dog, trick))
+        self.save(add_trick(dog, Trick(name=trick)))
 
     def get_dog(self, dog_id: UUID) -> Dict[str, Any]:
         dog = self.repository.get(dog_id, projector_func=project_dog)

eventsourcing/examples/aggregate7/domainmodel.py

@@ -68,17 +68,21 @@ def project_aggregate(
     return project_aggregate
 
 
+class Trick(BaseModel):
+    name: str
+
+
 class Dog(Aggregate):
     name: str
-    tricks: Tuple[str, ...]
+    tricks: Tuple[Trick, ...]
 
 
 class DogRegistered(DomainEvent):
     name: str
 
 
 class TrickAdded(DomainEvent):
-    trick: str
+    trick: Trick
 
 
 def register_dog(name: str) -> DomainEvent:
@@ -90,7 +94,7 @@ def register_dog(name: str) -> DomainEvent:
     )
 
 
-def add_trick(dog: Dog, trick: str) -> DomainEvent:
+def add_trick(dog: Dog, trick: Trick) -> DomainEvent:
     return TrickAdded(
         originator_id=dog.id,
         originator_version=dog.version + 1,

eventsourcing/examples/aggregate7/test_application.py

@@ -1,7 +1,8 @@
+from typing import Tuple
 from unittest import TestCase
 
 from eventsourcing.examples.aggregate7.application import DogSchool
-from eventsourcing.examples.aggregate7.domainmodel import project_dog
+from eventsourcing.examples.aggregate7.domainmodel import Trick, project_dog
 
 
 class TestDogSchool(TestCase):
@@ -16,8 +17,8 @@ def test_dog_school(self) -> None:
 
         # Query application state.
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
 
         # Select notifications.
         notifications = school.notification_log.select(start=1, limit=10)
@@ -26,11 +27,19 @@ def test_dog_school(self) -> None:
         # Take snapshot.
         school.take_snapshot(dog_id, version=3, projector_func=project_dog)
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
 
         # Continue with snapshotted aggregate.
         school.add_trick(dog_id, "fetch ball")
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead", "fetch ball")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead", "fetch ball"))
+
+    def assertEqualTricks(
+        self, actual: Tuple[Trick, ...], expected: Tuple[str, ...]
+    ) -> None:
+        self.assertEqual(len(actual), len(expected))
+        for i, trick in enumerate(actual):
+            self.assertIsInstance(trick, Trick)
+            self.assertEqual(trick.name, expected[i])

eventsourcing/examples/aggregate7/test_compression_and_encryption.py

@@ -1,8 +1,9 @@
+from typing import Tuple
 from unittest import TestCase
 
 from eventsourcing.cipher import AESCipher
 from eventsourcing.examples.aggregate7.application import DogSchool
-from eventsourcing.examples.aggregate7.domainmodel import project_dog
+from eventsourcing.examples.aggregate7.domainmodel import Trick, project_dog
 
 
 class TestDogSchool(TestCase):
@@ -24,7 +25,7 @@ def test_dog_school(self) -> None:
         # Query application state.
         dog = school.get_dog(dog_id)
         assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
 
         # Select notifications.
         notifications = school.notification_log.select(start=1, limit=10)
@@ -34,10 +35,18 @@ def test_dog_school(self) -> None:
         school.take_snapshot(dog_id, version=3, projector_func=project_dog)
         dog = school.get_dog(dog_id)
         assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
 
         # Continue with snapshotted aggregate.
         school.add_trick(dog_id, "fetch ball")
         dog = school.get_dog(dog_id)
         assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead", "fetch ball")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead", "fetch ball"))
+
+    def assertEqualTricks(
+        self, actual: Tuple[Trick, ...], expected: Tuple[str, ...]
+    ) -> None:
+        self.assertEqual(len(actual), len(expected))
+        for i, trick in enumerate(actual):
+            self.assertIsInstance(trick, Trick)
+            self.assertEqual(trick.name, expected[i])

eventsourcing/examples/aggregate7/test_snapshotting_intervals.py

@@ -1,11 +1,12 @@
-from typing import cast
+from typing import Tuple, cast
 from unittest import TestCase
 from uuid import UUID
 
 from eventsourcing.domain import ProgrammingError
 from eventsourcing.examples.aggregate7.application import DogSchool
 from eventsourcing.examples.aggregate7.domainmodel import (
     Dog,
+    Trick,
     add_trick,
     project_dog,
     register_dog,
@@ -23,7 +24,7 @@ def register_dog(self, name: str) -> UUID:
 
     def add_trick(self, dog_id: UUID, trick: str) -> None:
         dog = self.repository.get(dog_id, projector_func=project_dog)
-        event = add_trick(dog, trick)
+        event = add_trick(dog, Trick(name=trick))
         dog = cast(Dog, project_dog(dog, [event]))
         self.save(dog, event)
 
@@ -58,5 +59,13 @@ def test_dog_school(self) -> None:
 
         # Query application state.
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
+
+    def assertEqualTricks(
+        self, actual: Tuple[Trick, ...], expected: Tuple[str, ...]
+    ) -> None:
+        self.assertEqual(len(actual), len(expected))
+        for i, trick in enumerate(actual):
+            self.assertIsInstance(trick, Trick)
+            self.assertEqual(trick.name, expected[i])

eventsourcing/examples/aggregate8/application.py

@@ -2,7 +2,7 @@
 from uuid import UUID
 
 from eventsourcing.application import Application
-from eventsourcing.examples.aggregate8.domainmodel import Dog, Snapshot
+from eventsourcing.examples.aggregate8.domainmodel import Dog, Trick
 from eventsourcing.examples.aggregate8.persistence import (
     OrjsonTranscoder,
     PydanticMapper,
@@ -12,7 +12,6 @@
 
 class DogSchool(Application):
     is_snapshotting_enabled = True
-    snapshot_class = Snapshot
 
     def register_dog(self, name: str) -> UUID:
         dog = Dog(name)
@@ -21,12 +20,17 @@ def register_dog(self, name: str) -> UUID:
 
     def add_trick(self, dog_id: UUID, trick: str) -> None:
         dog: Dog = self.repository.get(dog_id)
-        dog.add_trick(trick)
+        dog.add_trick(Trick(name=trick))
         self.save(dog)
 
     def get_dog(self, dog_id: UUID) -> Dict[str, Any]:
         dog: Dog = self.repository.get(dog_id)
-        return {"name": dog.name, "tricks": tuple(dog.tricks)}
+        return {
+            "name": dog.name,
+            "tricks": tuple(dog.tricks),
+            "created_on": dog.created_on,
+            "modified_on": dog.modified_on,
+        }
 
     def construct_mapper(self) -> Mapper:
         return self.factory.mapper(

eventsourcing/examples/aggregate8/domainmodel.py

@@ -1,8 +1,8 @@
 from datetime import datetime
-from typing import Any, Dict, List
+from typing import List
 from uuid import UUID
 
-from pydantic import BaseModel
+from pydantic import BaseModel, Extra
 
 from eventsourcing.domain import (
     Aggregate as BaseAggregate,
@@ -30,17 +30,34 @@ class Created(Event, CanInitAggregate):
         originator_topic: str
 
 
-class Snapshot(DomainEvent, CanSnapshotAggregate):
+class SnapshotState(BaseModel):
+    class Config:
+        extra = Extra.allow
+
+
+class AggregateSnapshot(DomainEvent, CanSnapshotAggregate):
     topic: str
-    state: Dict[str, Any]
+    state: SnapshotState
+
+
+class Trick(BaseModel):
+    name: str
+
+
+class DogState(SnapshotState):
+    name: str
+    tricks: List[Trick]
 
 
 class Dog(Aggregate):
+    class Snapshot(AggregateSnapshot):
+        state: DogState
+
     @event("Registered")
     def __init__(self, name: str) -> None:
         self.name = name
-        self.tricks: List[str] = []
+        self.tricks: List[Trick] = []
 
     @event("TrickAdded")
-    def add_trick(self, trick: str) -> None:
+    def add_trick(self, trick: Trick) -> None:
         self.tricks.append(trick)

eventsourcing/examples/aggregate8/test_application.py

@@ -1,6 +1,8 @@
+from typing import Tuple
 from unittest import TestCase
 
 from eventsourcing.examples.aggregate8.application import DogSchool
+from eventsourcing.examples.aggregate8.domainmodel import Trick
 
 
 class TestDogSchool(TestCase):
@@ -15,8 +17,8 @@ def test_dog_school(self) -> None:
 
         # Query application state.
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
 
         # Select notifications.
         notifications = school.notification_log.select(start=1, limit=10)
@@ -25,11 +27,19 @@ def test_dog_school(self) -> None:
         # Take snapshot.
         school.take_snapshot(dog_id, version=3)
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead"))
 
         # Continue with snapshotted aggregate.
         school.add_trick(dog_id, "fetch ball")
         dog = school.get_dog(dog_id)
-        assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead", "fetch ball")
+        self.assertEqual(dog["name"], "Fido")
+        self.assertEqualTricks(dog["tricks"], ("roll over", "play dead", "fetch ball"))
+
+    def assertEqualTricks(
+        self, actual: Tuple[Trick, ...], expected: Tuple[str, ...]
+    ) -> None:
+        self.assertEqual(len(actual), len(expected))
+        for i, trick in enumerate(actual):
+            self.assertIsInstance(trick, Trick)
+            self.assertEqual(trick.name, expected[i])

eventsourcing/examples/aggregate8/test_compression_and_encryption.py

@@ -2,6 +2,7 @@
 
 from eventsourcing.cipher import AESCipher
 from eventsourcing.examples.aggregate8.application import DogSchool
+from eventsourcing.examples.aggregate8.domainmodel import Trick
 
 
 class TestDogSchool(TestCase):
@@ -23,7 +24,7 @@ def test_dog_school(self) -> None:
         # Query application state.
         dog = school.get_dog(dog_id)
         assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        assert dog["tricks"] == (Trick(name="roll over"), Trick(name="play dead"))
 
         # Select notifications.
         notifications = school.notification_log.select(start=1, limit=10)
@@ -33,10 +34,14 @@ def test_dog_school(self) -> None:
         school.take_snapshot(dog_id, version=3)
         dog = school.get_dog(dog_id)
         assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead")
+        assert dog["tricks"] == (Trick(name="roll over"), Trick(name="play dead"))
 
         # Continue with snapshotted aggregate.
         school.add_trick(dog_id, "fetch ball")
         dog = school.get_dog(dog_id)
         assert dog["name"] == "Fido"
-        assert dog["tricks"] == ("roll over", "play dead", "fetch ball")
+        assert dog["tricks"] == (
+            Trick(name="roll over"),
+            Trick(name="play dead"),
+            Trick(name="fetch ball"),
+        )