Refactor webservice db stuff to use a single sessionmaker

solvable/src/webservice/model.py

@@ -1,9 +1,27 @@
+from contextlib import contextmanager
+
 from sqlalchemy import Column, Integer, String, create_engine
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
 
 engine = create_engine('sqlite:///db.db', convert_unicode=True)
+session_factory = sessionmaker(autocommit=False,
+                               autoflush=False,
+                               bind=engine)
+
+
+@contextmanager
+def Session():
+    session = session_factory()
+    try:
+        yield session
+        session.commit()
+    except:
+        session.rollback()
+        raise
+    finally:
+        session.close()
 
 
 Base = declarative_base()
@@ -19,21 +37,3 @@ class User(Base):
 
 def init_db():
     Base.metadata.create_all(bind=engine)
-
-
-class Session:
-    session = None
-
-    def __enter__(self):
-        self.session = Session.create()
-        return self.session
-
-    @staticmethod
-    def create():
-        factory = sessionmaker(autocommit=False,
-                               autoflush=False,
-                               bind=engine)
-        return factory()
-
-    def __exit__(self, exc_type, exc_val, exc_tb):
-        self.session.close()

solvable/src/webservice/user_ops.py

@@ -39,4 +39,3 @@ class UserOps:
             user = User(username=self.username,
                         passwordhash=PasswordHasher.hash(self.password))
             db.add(user)
-            db.commit()