Refactor database sessions into FastAPI dependency

dependencies.py

@@ -0,0 +1,17 @@
+from typing import Annotated
+
+from fastapi import Depends
+from sqlalchemy.orm import Session
+
+from database import engine
+
+
+def get_session():
+    with Session(engine, expire_on_commit=False) as session:
+        yield session
+
+
+SessionDep = Annotated[
+    Session,
+    Depends(get_session),
+]

main.py

@@ -2,11 +2,11 @@ from fastapi import FastAPI, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
 from pydantic import BaseModel
 from sqlalchemy import select
-from sqlalchemy.orm import Session
-from database import engine
-from models import Todo
 from sqlalchemy.exc import SQLAlchemyError
 
+from dependencies import SessionDep
+from models import Todo
+
 app = FastAPI()
 app.add_middleware(
         CORSMiddleware,
@@ -32,20 +32,20 @@ def health():
     return {"status":"ok"}
 
 @app.get("/todos", response_model=list[todoresponse])
-def todos_get():
-    with Session(engine) as session:
+def todos_get(session: SessionDep):
     statement = select(Todo)
     todos = session.scalars(statement).all()
     return todos
 
 @app.post("/todos", response_model=todoresponse)
-def todos_create(todo_data:todocreate):
-    with Session(engine) as session:
+def todos_create(
+    todo_data: todocreate,
+    session: SessionDep,
+):
     try:
         new_todo = Todo(task=todo_data.task)
         session.add(new_todo)
         session.commit()
-            session.refresh(new_todo)
         return new_todo
     except SQLAlchemyError:
         session.rollback()
@@ -53,8 +53,11 @@ def todos_create(todo_data:todocreate):
 
 
 @app.patch("/todos/{todo_id}", response_model=todoresponse)
-def todos_patch(todo_id:int, update_data:todoupdate):
-    with Session(engine) as session:
+def todos_patch(
+    todo_id: int,
+    update_data: todoupdate,
+    session: SessionDep,
+):
     try:
         todo = session.get(Todo, todo_id)
         if todo is None:
@@ -64,7 +67,6 @@ def todos_patch(todo_id:int, update_data:todoupdate):
         if update_data.completion is not None:
             todo.completion = update_data.completion
         session.commit()
-            session.refresh(todo)
         return todo
     except SQLAlchemyError:
         session.rollback()
@@ -72,8 +74,10 @@ def todos_patch(todo_id:int, update_data:todoupdate):
 
 
 @app.delete("/todos/{todo_id}", response_model=todoresponse)
-def todos_delete(todo_id:int):
-    with Session(engine) as session:
+def todos_delete(
+    todo_id: int,
+    session: SessionDep,
+):
     try:
         todo = session.get(Todo, todo_id)
         if todo is None: