use uow in services, flask app

Author: hjwp

src/allocation/adapters/orm.py

@@ -41,7 +41,9 @@ def start_mappers():
         batches,
         properties={
             "_allocations": relationship(
-                lines_mapper, secondary=allocations, collection_class=set,
+                lines_mapper,
+                secondary=allocations,
+                collection_class=set,
             )
         },
     )

src/allocation/entrypoints/flask_app.py

@@ -3,20 +3,16 @@
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 
-from allocation import config
 from allocation.domain import model
-from allocation.adapters import orm, repository
-from allocation.service_layer import services
+from allocation.adapters import orm
+from allocation.service_layer import services, unit_of_work
 
-orm.start_mappers()
-get_session = sessionmaker(bind=create_engine(config.get_postgres_uri()))
 app = Flask(__name__)
+orm.start_mappers()
 
 
 @app.route("/add_batch", methods=["POST"])
 def add_batch():
-    session = get_session()
-    repo = repository.SqlAlchemyRepository(session)
     eta = request.json["eta"]
     if eta is not None:
         eta = datetime.fromisoformat(eta).date()
@@ -25,23 +21,19 @@ def add_batch():
         request.json["sku"],
         request.json["qty"],
         eta,
-        repo,
-        session,
+        unit_of_work.SqlAlchemyUnitOfWork(),
     )
     return "OK", 201
 
 
 @app.route("/allocate", methods=["POST"])
 def allocate_endpoint():
-    session = get_session()
-    repo = repository.SqlAlchemyRepository(session)
     try:
         batchref = services.allocate(
             request.json["orderid"],
             request.json["sku"],
             request.json["qty"],
-            repo,
-            session,
+            unit_of_work.SqlAlchemyUnitOfWork(),
         )
     except (model.OutOfStock, services.InvalidSku) as e:
         return {"message": str(e)}, 400

src/allocation/service_layer/services.py

@@ -4,7 +4,7 @@
 
 from allocation.domain import model
 from allocation.domain.model import OrderLine
-from allocation.adapters.repository import AbstractRepository
+from allocation.service_layer import unit_of_work
 
 
 class InvalidSku(Exception):
@@ -17,20 +17,22 @@ def is_valid_sku(sku, batches):
 
 def add_batch(
     ref: str, sku: str, qty: int, eta: Optional[date],
-    repo: AbstractRepository, session,
-) -> None:
-    repo.add(model.Batch(ref, sku, qty, eta))
-    session.commit()
+    uow: unit_of_work.AbstractUnitOfWork,
+):
+    with uow:
+        uow.batches.add(model.Batch(ref, sku, qty, eta))
+        uow.commit()
 
 
 def allocate(
     orderid: str, sku: str, qty: int,
-    repo: AbstractRepository, session,
+    uow: unit_of_work.AbstractUnitOfWork,
 ) -> str:
     line = OrderLine(orderid, sku, qty)
-    batches = repo.list()
-    if not is_valid_sku(line.sku, batches):
-        raise InvalidSku(f"Invalid sku {line.sku}")
-    batchref = model.allocate(line, batches)
-    session.commit()
+    with uow:
+        batches = uow.batches.list()
+        if not is_valid_sku(line.sku, batches):
+            raise InvalidSku(f"Invalid sku {line.sku}")
+        batchref = model.allocate(line, batches)
+        uow.commit()
     return batchref

src/allocation/unit_of_work.py …allocation/service_layer/unit_of_work.pysrc/allocation/unit_of_work.py renamed to src/allocation/service_layer/unit_of_work.py src/allocation/unit_of_work.py renamed to src/allocation/service_layer/unit_of_work.py

@@ -6,7 +6,7 @@
 from sqlalchemy.orm.session import Session
 
 from allocation import config
-from allocation import repository
+from allocation.adapters import repository
 
 
 class AbstractUnitOfWork(abc.ABC):
@@ -27,7 +27,11 @@ def rollback(self):
         raise NotImplementedError
 
 
-DEFAULT_SESSION_FACTORY = sessionmaker(bind=create_engine(config.get_postgres_uri(),))
+DEFAULT_SESSION_FACTORY = sessionmaker(
+    bind=create_engine(
+        config.get_postgres_uri(),
+    )
+)
 
 
 class SqlAlchemyUnitOfWork(AbstractUnitOfWork):

src/setup.py

@@ -1,5 +1,7 @@
 from setuptools import setup
 
 setup(
-    name="allocation", version="0.1", packages=["allocation"],
+    name="allocation",
+    version="0.1",
+    packages=["allocation"],
 )

tests/integration/test_uow.py

@@ -1,6 +1,5 @@
-import pytest
-from allocation import model
-from allocation import unit_of_work
+from allocation.domain import model
+from allocation.service_layer import unit_of_work
 
 
 def insert_batch(session, ref, sku, qty, eta):

tests/unit/test_services.py

@@ -1,6 +1,6 @@
 import pytest
 from allocation.adapters import repository
-from allocation.service_layer import services
+from allocation.service_layer import services, unit_of_work
 
 
 class FakeRepository(repository.AbstractRepository):
@@ -17,38 +17,42 @@ def list(self):
         return list(self._batches)
 
 
-class FakeSession:
-    committed = False
+class FakeUnitOfWork(unit_of_work.AbstractUnitOfWork):
+    def __init__(self):
+        self.batches = FakeRepository([])
+        self.committed = False
 
     def commit(self):
         self.committed = True
 
+    def rollback(self):
+        pass
+
 
 def test_add_batch():
-    repo, session = FakeRepository([]), FakeSession()
-    services.add_batch("b1", "CRUNCHY-ARMCHAIR", 100, None, repo, session)
-    assert repo.get("b1") is not None
-    assert session.committed
+    uow = FakeUnitOfWork()
+    services.add_batch("b1", "CRUNCHY-ARMCHAIR", 100, None, uow)
+    assert uow.batches.get("b1") is not None
+    assert uow.committed
 
 
 def test_allocate_returns_allocation():
-    repo, session = FakeRepository([]), FakeSession()
-    services.add_batch("batch1", "COMPLICATED-LAMP", 100, None, repo, session)
-    result = services.allocate("o1", "COMPLICATED-LAMP", 10, repo, session)
+    uow = FakeUnitOfWork()
+    services.add_batch("batch1", "COMPLICATED-LAMP", 100, None, uow)
+    result = services.allocate("o1", "COMPLICATED-LAMP", 10, uow)
     assert result == "batch1"
 
 
 def test_allocate_errors_for_invalid_sku():
-    repo, session = FakeRepository([]), FakeSession()
-    services.add_batch("b1", "AREALSKU", 100, None, repo, session)
+    uow = FakeUnitOfWork()
+    services.add_batch("b1", "AREALSKU", 100, None, uow)
 
     with pytest.raises(services.InvalidSku, match="Invalid sku NONEXISTENTSKU"):
-        services.allocate("o1", "NONEXISTENTSKU", 10, repo, FakeSession())
+        services.allocate("o1", "NONEXISTENTSKU", 10, uow)
 
 
-def test_commits():
-    repo, session = FakeRepository([]), FakeSession()
-    session = FakeSession()
-    services.add_batch("b1", "OMINOUS-MIRROR", 100, None, repo, session)
-    services.allocate("o1", "OMINOUS-MIRROR", 10, repo, session)
-    assert session.committed is True
+def test_allocate_commits():
+    uow = FakeUnitOfWork()
+    services.add_batch("b1", "OMINOUS-MIRROR", 100, None, uow)
+    services.allocate("o1", "OMINOUS-MIRROR", 10, uow)
+    assert uow.committed