ISSUE #99

* Add support for handling of not found cases to `LmdbDatabaseClient`.

Author: Sergio García Prado

packages/core/minos-microservice-common/minos/common/database/mixins.py

@@ -1,8 +1,11 @@
+from collections.abc import (
+    AsyncIterator,
+)
 from contextlib import (
     suppress,
 )
 from typing import (
-    AsyncIterator,
+    Any,
     Generic,
     Optional,
     TypeVar,
@@ -101,7 +104,7 @@ def _get_generic_operation_factory(self) -> Optional[type[GenericDatabaseOperati
                 raise TypeError(f"{type(self)!r} must contain a {DatabaseOperationFactory!r} as generic value.")
         return operation_factory_cls
 
-    async def execute_on_database_and_fetch_one(self, operation: DatabaseOperation) -> tuple:
+    async def execute_on_database_and_fetch_one(self, operation: DatabaseOperation) -> Any:
         """Submit an Operation and get the first response.
 
         :param operation: The operation to be executed.

packages/core/minos-microservice-saga/minos/saga/executions/repositories/database/impl.py

@@ -11,6 +11,7 @@
 
 from minos.common import (
     DatabaseMixin,
+    ProgrammingException,
 )
 
 from ....exceptions import (
@@ -46,8 +47,9 @@ async def _delete(self, uuid: UUID) -> None:
     async def _load(self, uuid: UUID) -> SagaExecution:
         operation = self.database_operation_factory.build_load(uuid)
 
-        value = await self.execute_on_database_and_fetch_one(operation)
-        if value is None:
+        try:
+            value = await self.execute_on_database_and_fetch_one(operation)
+        except ProgrammingException:
             raise SagaExecutionNotFoundException(f"The execution identified by {uuid} was not found.")
         execution = SagaExecution.from_raw(value)
         return execution

packages/core/minos-microservice-saga/tests/test_saga/test_executions/test_repositories/test_database/test_impl.py

@@ -5,6 +5,7 @@
 
 from minos.common import (
     DatabaseClient,
+    ProgrammingException,
 )
 from minos.saga import (
     DatabaseSagaExecutionRepository,
@@ -39,15 +40,15 @@ async def test_load_from_str(self):
             await super().test_load_from_str()
 
     async def test_load_raises(self):
-        with patch.object(DatabaseClient, "fetch_one", side_effect=[None]):
+        with patch.object(DatabaseClient, "fetch_one", side_effect=[ProgrammingException("")]):
             await super().test_load_raises()
 
     async def test_delete(self):
-        with patch.object(DatabaseClient, "fetch_one", side_effect=[None]):
+        with patch.object(DatabaseClient, "fetch_one", side_effect=[ProgrammingException("")]):
             await super().test_delete()
 
     async def test_delete_from_str(self):
-        with patch.object(DatabaseClient, "fetch_one", side_effect=[None]):
+        with patch.object(DatabaseClient, "fetch_one", side_effect=[ProgrammingException("")]):
             await super().test_delete_from_str()
 
 

packages/core/minos-microservice-saga/tests/test_saga/test_manager.py

@@ -17,6 +17,7 @@
     DatabaseClient,
     DatabaseClientPool,
     NotProvidedException,
+    ProgrammingException,
 )
 from minos.networks import (
     REQUEST_HEADERS_CONTEXT_VAR,
@@ -109,7 +110,7 @@ async def test_run_with_pause_on_memory(self):
 
         self.assertEqual(SagaStatus.Finished, execution.status)
         with self.assertRaises(SagaExecutionNotFoundException):
-            with patch.object(DatabaseClient, "fetch_one", side_effect=[None]):
+            with patch.object(DatabaseClient, "fetch_one", side_effect=[ProgrammingException("")]):
                 await self.manager.storage.load(execution.uuid)
 
         observed = self.broker_publisher.messages
@@ -190,7 +191,7 @@ async def test_run_with_pause_on_disk(self):
             self.assertEqual(SagaStatus.Finished, execution.status)
 
         with self.assertRaises(SagaExecutionNotFoundException):
-            with patch.object(DatabaseClient, "fetch_one", side_effect=[None]):
+            with patch.object(DatabaseClient, "fetch_one", side_effect=[ProgrammingException("")]):
                 await self.manager.storage.load(self.uuid)
 
         observed = self.broker_publisher.messages

packages/plugins/minos-database-lmdb/minos/plugins/lmdb/clients.py

@@ -27,6 +27,8 @@
     LmdbDatabaseOperationType,
 )
 
+not_found_sentinel = object()
+
 
 class LmdbDatabaseClient(DatabaseClient):
     """Lmdb Database Client class."""
@@ -52,7 +54,7 @@ def __init__(
         self._protocol = protocol
         self._tables = {}
 
-        self._prefetched = None
+        self._prefetched = not_found_sentinel
 
         self._environment = None
 
@@ -79,8 +81,10 @@ async def _reset(self, **kwargs) -> None:
         self._environment.sync()
 
     async def _fetch_all(self, *args, **kwargs) -> Any:
+        if self._prefetched is not_found_sentinel:
+            return
         prefetched = self._prefetched
-        self._prefetched = None
+        self._prefetched = not_found_sentinel
         yield prefetched
 
     async def _execute(self, operation: DatabaseOperation) -> None:
@@ -109,11 +113,9 @@ def _create(self, table: str, key: str, value: Any, **kwargs) -> None:
     def _read(self, table: str, key: str, **kwargs):
         table = self._get_table(table)
         with self._environment.begin(db=table) as transaction:
-            value_binary = transaction.get(key.encode())
-            if value_binary is not None:
-                value = self._protocol.decode(value_binary)
-            else:
-                value = None
+            value = transaction.get(key.encode(), default=not_found_sentinel)
+            if value is not not_found_sentinel:
+                value = self._protocol.decode(value)
 
         self._prefetched = value
 

packages/plugins/minos-database-lmdb/tests/test_lmdb/test_clients.py

@@ -7,6 +7,7 @@
 from minos.common import (
     DatabaseClient,
     DatabaseOperation,
+    ProgrammingException,
 )
 from minos.plugins.lmdb import (
     LmdbDatabaseClient,
@@ -146,7 +147,8 @@ async def test_execute_delete(self):
             self.assertEqual("Text Second Value", await client.fetch_one())
 
             await client.execute(read_op_2)
-            self.assertEqual(None, await client.fetch_one())
+            with self.assertRaises(ProgrammingException):
+                self.assertEqual(None, await client.fetch_one())
 
     async def test_execute_update(self):
         create_op = LmdbDatabaseOperation(LmdbDatabaseOperationType.CREATE, "TestOne", "first", "Text Value")

packages/plugins/minos-database-lmdb/tests/test_lmdb/test_factories/test_saga/test_factories.py

@@ -25,7 +25,6 @@ def test_build_store(self):
         self.assertEqual(LmdbDatabaseOperationType.CREATE, operation.type_)
 
     def test_build_load(self):
-        pass
         factory = LmdbSagaExecutionDatabaseOperationFactory()
 
         operation = factory.build_load(uuid4())