1 files changed, 40 insertions, 0 deletions
diff --git a/Zettelkast/Notes/290220241458 - Unit of Work pattern.md b/Zettelkast/Notes/290220241458 - Unit of Work pattern.md
new file mode 100644
index 0000000..3ba00cb
--- /dev/null
+++ b/Zettelkast/Notes/290220241458 - Unit of Work pattern.md
@@ -0,0 +1,40 @@
+#needs-clarification
+
+The Unit of Work is an abstraction of the concept of atomic operations. We can have a clear boundary on what work is grouped together and should be committed only if everything succeeded.
+
+We can use the UoW to remove dependency on storage layer from entrypoints by having the UoW manage the set-up. This makes tests easier.
+
+For example an SqlAlchemyUoW can wrap an SqlAlchemy Session object and expose only its most thin API: commit and rollback. It can work together as well with a [[022920240901 - Repository Pattern|Repository]]. Using a ContextManager we can make  the operations safe by only explicitly having the user of the UoW commit and otherwise when exiting do a rollback:
+```py
+import abc
+
+class AbstractUnitOfWork(abc.ABC):
+	products: AbstractRepository
+
+	def __init__(self, products: AbstractRepository):
+		self.products = products
+
+	def __exit__(self):
+		self.rollback()
+
+	@abc.abstractmethod
+	def commit(self):
+		pass
+
+	@abc.abstractmethod
+	def rollback(self):
+		pass
+
+
+class SqlAlchemyUnitOfWork(AbstractUnitOfWork):
+	def __init__(self, products: AbstractRepository, sessionmaker):
+		self._session = sessionmaker()
+		super().__init__(some_repo)
+
+	def commit(self):
+		self._session.commit()
+
+	def rollback(self):
+		self._session.rollback()
+```
+