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,
@@ -32,55 +32,59 @@ def health():
     return {"status":"ok"}
 
 @app.get("/todos", response_model=list[todoresponse])
-def todos_get():
+def todos_get(session: SessionDep):
-    with Session(engine) as session:
+    statement = select(Todo)
-        statement = select(Todo)
+    todos = session.scalars(statement).all()
-        todos = session.scalars(statement).all()
+    return todos
-        return todos
 
 @app.post("/todos", response_model=todoresponse)
-def todos_create(todo_data:todocreate):
+def todos_create(
-    with Session(engine) as session:
+    todo_data: todocreate,
-        try:
+    session: SessionDep,
-            new_todo = Todo(task = todo_data.task)
+):
-            session.add(new_todo)
+    try:
-            session.commit()
+        new_todo = Todo(task=todo_data.task)
-            session.refresh(new_todo)
+        session.add(new_todo)
-            return new_todo
+        session.commit()
-        except SQLAlchemyError:
+        return new_todo
-            session.rollback()
+    except SQLAlchemyError:
-            raise
+        session.rollback()
+        raise
 
 
 @app.patch("/todos/{todo_id}", response_model=todoresponse)
-def todos_patch(todo_id:int, update_data:todoupdate):
+def todos_patch(
-    with Session(engine) as session:
+    todo_id: int,
-        try:
+    update_data: todoupdate,
-            todo = session.get(Todo, todo_id)
+    session: SessionDep,
-            if todo is None:
+):
-                raise HTTPException(status_code = 404, detail = "Todo not found")
+    try:
-            if update_data.task is not None:
+        todo = session.get(Todo, todo_id)
-                todo.task = update_data.task
+        if todo is None:
-            if update_data.completion is not None:
+            raise HTTPException(status_code = 404, detail = "Todo not found")
-                todo.completion = update_data.completion
+        if update_data.task is not None:
-            session.commit()
+            todo.task = update_data.task
-            session.refresh(todo)
+        if update_data.completion is not None:
-            return todo
+            todo.completion = update_data.completion
-        except SQLAlchemyError:
+        session.commit()
-            session.rollback()
+        return todo
-            raise
+    except SQLAlchemyError:
+        session.rollback()
+        raise
 
 
 @app.delete("/todos/{todo_id}", response_model=todoresponse)
-def todos_delete(todo_id:int):
+def todos_delete(
-    with Session(engine) as session:
+    todo_id: int,
-        try:
+    session: SessionDep,
-            todo = session.get(Todo, todo_id)
+):
-            if todo is None:
+    try:
-                raise HTTPException(status_code = 404, detail = "Todo not found")
+        todo = session.get(Todo, todo_id)
-            session.delete(todo)
+        if todo is None:
-            session.commit()
+            raise HTTPException(status_code = 404, detail = "Todo not found")
-            return todo
+        session.delete(todo)
-        except SQLAlchemyError:
+        session.commit()
-            session.rollback()
+        return todo
-            raise
+    except SQLAlchemyError:
+        session.rollback()
+        raise