def __init__(self,
event_store,
mutator=None,
snapshot_strategy=None,
use_cache=False,
*args,
**kwargs):
super(EventSourcedRepository, self).__init__(*args, **kwargs)
self._cache = {}
self._snapshot_strategy = snapshot_strategy
# self._use_cache = use_cache
# Check we got an event store.
assert isinstance(event_store, AbstractEventStore), type(event_store)
self._event_store = event_store
# Instantiate an event player for this repo.
mutator = mutator or type(self).mutator
self.event_player = EventPlayer(
event_store=self.event_store,
mutator=mutator,
page_size=self.__page_size__,
is_short=self.__is_short__,
snapshot_strategy=self._snapshot_strategy,
)
def __init__(self,
event_store,
mutator=None,
snapshot_strategy=None,
use_cache=False):
self._cache = {}
self._snapshot_strategy = snapshot_strategy
# self._use_cache = use_cache
# Check we got an event store.
assert isinstance(event_store, AbstractEventStore)
self.event_store = event_store
# Instantiate an event player for this repo.
mutator = mutator or type(self).mutator
if mutator is None:
raise ValueError(
"Repository needs a mutator function (set class attribute or pass constructor arg)"
)
self.event_player = EventPlayer(
event_store=self.event_store,
mutator=mutator,
page_size=self.__page_size__,
is_short=self.__is_short__,
snapshot_strategy=self._snapshot_strategy,
)
def test_replay_entity(self):
# Store example events.
# Create entity1.
entity_id1 = uuid4()
event1 = Example.Created(originator_id=entity_id1, a=1, b=2)
self.entity_event_store.append(event1)
# Create entity2.
entity_id2 = uuid4()
event2 = Example.Created(originator_id=entity_id2, a=2, b=4)
self.entity_event_store.append(event2)
# Create entity3.
entity_id3 = uuid4()
event3 = Example.Created(originator_id=entity_id3, a=3, b=6)
self.entity_event_store.append(event3)
# Discard entity3.
event4 = Example.Discarded(originator_id=entity_id3,
originator_version=1)
self.entity_event_store.append(event4)
# Check the entities can be replayed.
event_player = EventPlayer(event_store=self.entity_event_store,
mutator=Example._mutate)
# Check recovered entities have correct attribute values.
recovered1 = event_player.replay_entity(entity_id1)
self.assertEqual(entity_id1, recovered1.id)
self.assertEqual(1, recovered1.a)
recovered2 = event_player.replay_entity(entity_id2)
self.assertEqual(2, recovered2.a)
recovered3 = event_player.replay_entity(entity_id3)
self.assertEqual(None, recovered3)
# Check it works for "short" entities (should be faster, but the main thing is that it still works).
# - just use a trivial mutate that always instantiates the 'Example'.
event5 = Example.AttributeChanged(originator_id=entity_id1,
originator_version=1,
name='a',
value=10)
self.entity_event_store.append(event5)
recovered1 = event_player.replay_entity(entity_id1)
self.assertEqual(10, recovered1.a)
event_player = EventPlayer(
event_store=self.entity_event_store,
mutator=Example._mutate,
is_short=True,
)
self.assertEqual(10, event_player.replay_entity(entity_id1).a)
def test_replay_entity(self):
# Store example events.
# Create entity1.
entity_id1 = uuid4()
event1 = Example.Created(originator_id=entity_id1, a=1, b=2)
self.entity_event_store.append(event1)
# Create entity2.
entity_id2 = uuid4()
event2 = Example.Created(originator_id=entity_id2, a=2, b=4)
self.entity_event_store.append(event2)
# Create entity3.
entity_id3 = uuid4()
event3 = Example.Created(originator_id=entity_id3, a=3, b=6)
self.entity_event_store.append(event3)
# Discard entity3.
event4 = Example.Discarded(originator_id=entity_id3, originator_version=1)
self.entity_event_store.append(event4)
# Check the entities can be replayed.
event_player = EventPlayer(event_store=self.entity_event_store, mutator=Example._mutate)
# Check recovered entities have correct attribute values.
recovered1 = event_player.replay_entity(entity_id1)
self.assertEqual(entity_id1, recovered1.id)
self.assertEqual(1, recovered1.a)
recovered2 = event_player.replay_entity(entity_id2)
self.assertEqual(2, recovered2.a)
recovered3 = event_player.replay_entity(entity_id3)
self.assertEqual(None, recovered3)
# Check it works for "short" entities (should be faster, but the main thing is that it still works).
# - just use a trivial mutate that always instantiates the 'Example'.
event5 = Example.AttributeChanged(originator_id=entity_id1, originator_version=1, name='a', value=10)
self.entity_event_store.append(event5)
recovered1 = event_player.replay_entity(entity_id1)
self.assertEqual(10, recovered1.a)
event_player = EventPlayer(
event_store=self.entity_event_store,
mutator=Example._mutate,
is_short=True,
)
self.assertEqual(10, event_player.replay_entity(entity_id1).a)
def __init__(self, event_store, mutator=None, snapshot_strategy=None, use_cache=False, *args, **kwargs):
super(EventSourcedRepository, self).__init__(*args, **kwargs)
self._cache = {}
self._snapshot_strategy = snapshot_strategy
# self._use_cache = use_cache
# Check we got an event store.
assert isinstance(event_store, AbstractEventStore), type(event_store)
self._event_store = event_store
# Instantiate an event player for this repo.
mutator = mutator or type(self).mutator
self.event_player = EventPlayer(
event_store=self.event_store,
mutator=mutator,
page_size=self.__page_size__,
is_short=self.__is_short__,
snapshot_strategy=self._snapshot_strategy,
)
def test_take_snapshot(self):
self.entity_persistence_policy = PersistencePolicy(
event_store=self.entity_event_store,
event_type=VersionedEntity.Event,
)
self.snapshot_persistence_policy = PersistencePolicy(
event_store=self.snapshot_store,
event_type=Snapshot,
)
snapshot_strategy = EventSourcedSnapshotStrategy(
event_store=self.snapshot_store
)
event_player = EventPlayer(
event_store=self.entity_event_store,
mutator=Example._mutate,
snapshot_strategy=snapshot_strategy
)
# Take a snapshot with a non-existent ID.
unregistered_id = uuid4()
# Check no snapshot is taken.
self.assertIsNone(event_player.take_snapshot(unregistered_id))
# Check no snapshot is available.
self.assertIsNone(event_player.get_snapshot(unregistered_id))
# Create a new entity.
registered_example = create_new_example(a=123, b=234)
# Take a snapshot of the new entity (no previous snapshots).
snapshot1 = event_player.take_snapshot(registered_example.id, lt=registered_example.version)
# Check the snapshot is pegged to the last applied version.
self.assertEqual(snapshot1.originator_version, 0)
# Replay from this snapshot.
entity_from_snapshot1 = entity_from_snapshot(snapshot1)
retrieved_example = event_player.replay_entity(registered_example.id,
initial_state=entity_from_snapshot1,
gte=entity_from_snapshot1._version)
# Check the attributes are correct.
self.assertEqual(retrieved_example.a, 123)
# Remember the version now.
version1 = retrieved_example._version
self.assertEqual(version1, 1)
# Change attribute value.
retrieved_example.a = 999
# Remember the version now.
version2 = retrieved_example._version
self.assertEqual(version2, 2)
# Change attribute value.
retrieved_example.a = 9999
# Remember the version now.
version3 = retrieved_example._version
self.assertEqual(version3, 3)
# Check the event sourced entities are correct.
retrieved_example = event_player.replay_entity(registered_example.id)
self.assertEqual(retrieved_example.a, 9999)
# Take another snapshot.
snapshot2 = event_player.take_snapshot(retrieved_example.id, lt=retrieved_example.version)
# Replay from this snapshot.
initial_state = entity_from_snapshot(snapshot2)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=initial_state,
gte=initial_state._version,
)
# Check the attributes are correct.
self.assertEqual(retrieved_example.a, 9999)
# Check we can get historical state at version1.
retrieved_example = event_player.replay_entity(registered_example.id, lt=version1)
self.assertEqual(retrieved_example.a, 123)
# Check we can get historical state at version2.
retrieved_example = event_player.replay_entity(registered_example.id, lt=version2)
self.assertEqual(retrieved_example.a, 999)
# Check we can get historical state at version3.
retrieved_example = event_player.replay_entity(registered_example.id, lt=version3)
self.assertEqual(retrieved_example.a, 9999)
# Similarly, check we can get historical state using a snapshot
initial_state = entity_from_snapshot(snapshot1)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=initial_state,
gte=initial_state._version,
lt=version2,
)
self.assertEqual(retrieved_example.a, 999)
# Discard the entity.
registered_example = event_player.replay_entity(registered_example.id)
registered_example.discard()
# Take snapshot of discarded entity.
snapshot3 = event_player.take_snapshot(registered_example.id)
self.assertIsNone(snapshot3.state)
self.assertIsNone(entity_from_snapshot(snapshot3))
class EventSourcedRepository(AbstractEntityRepository):
# If the entity won't have very many events, marking the entity as
# "short" by setting __is_short__ value equal to True will mean
# the fastest path for getting all the events is used. If you set
# a value for page size (see below), this option will have no effect.
__is_short__ = False
# The page size by which events are retrieved. If this
# value is set to a positive integer, the events of
# the entity will be retrieved in pages, using a series
# of queries, rather than with one potentially large query.
__page_size__ = None
# The mutator function used by this repository. Can either
# be set as a class attribute, or passed as a constructor arg.
mutator = mutate_entity
def __init__(self, event_store, mutator=None, snapshot_strategy=None, use_cache=False, *args, **kwargs):
super(EventSourcedRepository, self).__init__(*args, **kwargs)
self._cache = {}
self._snapshot_strategy = snapshot_strategy
# self._use_cache = use_cache
# Check we got an event store.
assert isinstance(event_store, AbstractEventStore), type(event_store)
self._event_store = event_store
# Instantiate an event player for this repo.
mutator = mutator or type(self).mutator
self.event_player = EventPlayer(
event_store=self.event_store,
mutator=mutator,
page_size=self.__page_size__,
is_short=self.__is_short__,
snapshot_strategy=self._snapshot_strategy,
)
@property
def event_store(self):
return self._event_store
def __contains__(self, entity_id):
"""
Returns a boolean value according to whether entity with given ID exists.
"""
return self.get_entity(entity_id) is not None
def __getitem__(self, entity_id):
"""
Returns entity with given ID.
"""
# # Get entity from the cache.
# if self._use_cache:
# try:
# return self._cache[entity_id]
# except KeyError:
# pass
# Reconstitute the entity.
entity = self.get_entity(entity_id)
# Never created or already discarded?
if entity is None:
raise RepositoryKeyError(entity_id)
# # Put entity in the cache.
# if self._use_cache:
# self.add_cache(entity_id, entity)
# Return entity.
return entity
# def add_cache(self, entity_id, entity):
# self._cache[entity_id] = entity
def get_entity(self, entity_id, lt=None, lte=None):
"""
Returns entity with given ID, optionally until position.
"""
# Get a snapshot (None if none exist).
if self._snapshot_strategy is not None:
snapshot = self._snapshot_strategy.get_snapshot(entity_id, lt=lt, lte=lte)
else:
snapshot = None
# Decide the initial state of the entity, and the
# version of the last item applied to the entity.
if snapshot is None:
initial_state = None
gt = None
else:
initial_state = entity_from_snapshot(snapshot)
gt = snapshot.originator_version
# Replay domain events.
return self.event_player.replay_entity(entity_id, gt=gt, lt=lt, lte=lte, initial_state=initial_state)
def take_snapshot(self, entity_id, lt=None, lte=None):
return self.event_player.take_snapshot(entity_id, lt=lt, lte=lte)
def test_take_snapshot(self):
self.entity_persistence_policy = PersistencePolicy(
event_store=self.entity_event_store,
event_type=VersionedEntity.Event,
)
self.snapshot_persistence_policy = PersistencePolicy(
event_store=self.snapshot_store,
event_type=Snapshot,
)
snapshot_strategy = EventSourcedSnapshotStrategy(
event_store=self.snapshot_store)
event_player = EventPlayer(event_store=self.entity_event_store,
mutator=Example._mutate,
snapshot_strategy=snapshot_strategy)
# Take a snapshot with a non-existent ID.
unregistered_id = uuid4()
# Check no snapshot is taken.
self.assertIsNone(event_player.take_snapshot(unregistered_id))
# Check no snapshot is available.
self.assertIsNone(event_player.get_snapshot(unregistered_id))
# Create a new entity.
registered_example = create_new_example(a=123, b=234)
# Take a snapshot of the new entity (no previous snapshots).
snapshot1 = event_player.take_snapshot(registered_example.id,
lt=registered_example.version)
# Check the snapshot is pegged to the last applied version.
self.assertEqual(snapshot1.originator_version, 0)
# Replay from this snapshot.
entity_from_snapshot1 = entity_from_snapshot(snapshot1)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=entity_from_snapshot1,
gte=entity_from_snapshot1._version)
# Check the attributes are correct.
self.assertEqual(retrieved_example.a, 123)
# Remember the version now.
version1 = retrieved_example._version
self.assertEqual(version1, 1)
# Change attribute value.
retrieved_example.a = 999
# Remember the version now.
version2 = retrieved_example._version
self.assertEqual(version2, 2)
# Change attribute value.
retrieved_example.a = 9999
# Remember the version now.
version3 = retrieved_example._version
self.assertEqual(version3, 3)
# Check the event sourced entities are correct.
retrieved_example = event_player.replay_entity(registered_example.id)
self.assertEqual(retrieved_example.a, 9999)
# Take another snapshot.
snapshot2 = event_player.take_snapshot(retrieved_example.id,
lt=retrieved_example.version)
# Replay from this snapshot.
initial_state = entity_from_snapshot(snapshot2)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=initial_state,
gte=initial_state._version,
)
# Check the attributes are correct.
self.assertEqual(retrieved_example.a, 9999)
# Check we can get historical state at version1.
retrieved_example = event_player.replay_entity(registered_example.id,
lt=version1)
self.assertEqual(retrieved_example.a, 123)
# Check we can get historical state at version2.
retrieved_example = event_player.replay_entity(registered_example.id,
lt=version2)
self.assertEqual(retrieved_example.a, 999)
# Check we can get historical state at version3.
retrieved_example = event_player.replay_entity(registered_example.id,
lt=version3)
self.assertEqual(retrieved_example.a, 9999)
# Similarly, check we can get historical state using a snapshot
initial_state = entity_from_snapshot(snapshot1)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=initial_state,
gte=initial_state._version,
lt=version2,
)
self.assertEqual(retrieved_example.a, 999)
# Discard the entity.
registered_example = event_player.replay_entity(registered_example.id)
registered_example.discard()
# Take snapshot of discarded entity.
snapshot3 = event_player.take_snapshot(registered_example.id)
self.assertIsNone(snapshot3.state)
self.assertIsNone(entity_from_snapshot(snapshot3))
class EventSourcedRepository(AbstractEntityRepository):
# If the entity won't have very many events, marking the entity as
# "short" by setting __is_short__ value equal to True will mean
# the fastest path for getting all the events is used. If you set
# a value for page size (see below), this option will have no effect.
__is_short__ = False
# The page size by which events are retrieved. If this
# value is set to a positive integer, the events of
# the entity will be retrieved in pages, using a series
# of queries, rather than with one potentially large query.
__page_size__ = None
# The mutator function used by this repository. Can either
# be set as a class attribute, or passed as a constructor arg.
mutator = mutate_entity
def __init__(self,
event_store,
mutator=None,
snapshot_strategy=None,
use_cache=False,
*args,
**kwargs):
super(EventSourcedRepository, self).__init__(*args, **kwargs)
self._cache = {}
self._snapshot_strategy = snapshot_strategy
# self._use_cache = use_cache
# Check we got an event store.
assert isinstance(event_store, AbstractEventStore), type(event_store)
self._event_store = event_store
# Instantiate an event player for this repo.
mutator = mutator or type(self).mutator
self.event_player = EventPlayer(
event_store=self.event_store,
mutator=mutator,
page_size=self.__page_size__,
is_short=self.__is_short__,
snapshot_strategy=self._snapshot_strategy,
)
@property
def event_store(self):
return self._event_store
def __contains__(self, entity_id):
"""
Returns a boolean value according to whether entity with given ID exists.
"""
return self.get_entity(entity_id) is not None
def __getitem__(self, entity_id):
"""
Returns entity with given ID.
"""
# # Get entity from the cache.
# if self._use_cache:
# try:
# return self._cache[entity_id]
# except KeyError:
# pass
# Reconstitute the entity.
entity = self.get_entity(entity_id)
# Never created or already discarded?
if entity is None:
raise RepositoryKeyError(entity_id)
# # Put entity in the cache.
# if self._use_cache:
# self.add_cache(entity_id, entity)
# Return entity.
return entity
# def add_cache(self, entity_id, entity):
# self._cache[entity_id] = entity
def get_entity(self, entity_id, lt=None, lte=None):
"""
Returns entity with given ID, optionally until position.
"""
# Get a snapshot (None if none exist).
if self._snapshot_strategy is not None:
snapshot = self._snapshot_strategy.get_snapshot(entity_id,
lt=lt,
lte=lte)
else:
snapshot = None
# Decide the initial state of the entity, and the
# version of the last item applied to the entity.
if snapshot is None:
initial_state = None
gt = None
else:
initial_state = entity_from_snapshot(snapshot)
gt = snapshot.originator_version
# Replay domain events.
return self.event_player.replay_entity(entity_id,
gt=gt,
lt=lt,
lte=lte,
initial_state=initial_state)
def take_snapshot(self, entity_id, lt=None, lte=None):
return self.event_player.take_snapshot(entity_id, lt=lt, lte=lte)
def test_get_entity(self):
# Store example events.
entity_id1 = uuid4()
event1 = Example.Created(entity_id=entity_id1, a=1, b=2)
self.version_entity_event_store.append(event1)
entity_id2 = uuid4()
event2 = Example.Created(entity_id=entity_id2, a=2, b=4)
self.version_entity_event_store.append(event2)
entity_id3 = uuid4()
event3 = Example.Created(entity_id=entity_id3, a=3, b=6)
self.version_entity_event_store.append(event3)
event4 = Example.Discarded(entity_id=entity_id3, entity_version=1)
self.version_entity_event_store.append(event4)
# Check the event sourced entities are correct.
# - just use a trivial mutate that always instantiates the 'Example'.
event_player = EventPlayer(event_store=self.version_entity_event_store, mutator=Example.mutate)
# The the reconstituted entity has correct attribute values.
self.assertEqual(entity_id1, event_player.replay_entity(entity_id1).id)
self.assertEqual(1, event_player.replay_entity(entity_id1).a)
self.assertEqual(2, event_player.replay_entity(entity_id2).a)
self.assertEqual(None, event_player.replay_entity(entity_id3))
# Check entity3 raises KeyError.
self.assertEqual(event_player.replay_entity(entity_id3), None)
# Check it works for "short" entities (should be faster, but the main thing is that it still works).
# - just use a trivial mutate that always instantiates the 'Example'.
event5 = Example.AttributeChanged(entity_id=entity_id1, entity_version=1, name='a', value=10)
self.version_entity_event_store.append(event5)
event_player = EventPlayer(event_store=self.version_entity_event_store, mutator=Example.mutate)
self.assertEqual(10, event_player.replay_entity(entity_id1).a)
event_player = EventPlayer(
event_store=self.version_entity_event_store,
mutator=Example.mutate,
is_short=True,
)
self.assertEqual(10, event_player.replay_entity(entity_id1).a)
def test_snapshots(self):
self.policy = CombinedPersistencePolicy(
versioned_entity_event_store=self.version_entity_event_store,
timestamped_entity_event_store=self.timestamp_entity_event_store,
)
event_player = EventPlayer(
event_store=self.version_entity_event_store,
mutator=Example.mutate,
snapshot_strategy=EventSourcedSnapshotStrategy(
event_store=self.timestamp_entity_event_store
)
)
# Take a snapshot with a non-existent ID.
self.assertIsNone(event_player.take_snapshot(uuid4()))
# Create a new entity.
registered_example = register_new_example(a=123, b=234)
# Take a snapshot.
snapshot1 = event_player.take_snapshot(registered_example.id)
# Replay from this snapshot.
initial_state = entity_from_snapshot(snapshot1)
retrieved_example = event_player.replay_entity(registered_example.id,
initial_state=initial_state,
gte=initial_state._version)
# Check the attributes are correct.
self.assertEqual(retrieved_example.a, 123)
# Remember the version now.
version1 = retrieved_example._version
# Change attribute value.
retrieved_example.a = 999
# Remember the version now.
version2 = retrieved_example._version
# Change attribute value.
retrieved_example.a = 9999
# Remember the version now.
version3 = retrieved_example._version
# Check the event sourced entities are correct.
retrieved_example = event_player.replay_entity(registered_example.id)
self.assertEqual(retrieved_example.a, 9999)
# Take another snapshot.
snapshot2 = event_player.take_snapshot(retrieved_example.id)
# Check we can replay from this snapshot.
initial_state = entity_from_snapshot(snapshot2)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=initial_state,
gte=initial_state._version,
)
# Check the attributes are correct.
self.assertEqual(retrieved_example.a, 9999)
# Check we can get historical state at version1.
retrieved_example = event_player.replay_entity(registered_example.id, lt=version1)
self.assertEqual(retrieved_example.a, 123)
# Check we can get historical state at version2.
retrieved_example = event_player.replay_entity(registered_example.id, lt=version2)
self.assertEqual(retrieved_example.a, 999)
# Check we can get historical state at version3.
retrieved_example = event_player.replay_entity(registered_example.id, lt=version3)
self.assertEqual(retrieved_example.a, 9999)
# Similarly, check we can get historical state using a snapshot
initial_state = entity_from_snapshot(snapshot1)
retrieved_example = event_player.replay_entity(
registered_example.id,
initial_state=initial_state,
gte=initial_state._version,
lt=version2,
)
self.assertEqual(retrieved_example.a, 999)