```python
from fastapi import FastAPI
```

::: fastapi.FastAPI
    options:
        members:
            - openapi_version
            - webhooks
            - state
            - dependency_overrides
            - openapi
            - websocket
            - include_router
            - get
            - put
            - post
            - delete
            - options

            - url
            - base_url
            - headers
            - query_params
            - path_params
            - cookies
            - client
            - state
            - url_for
            - client_state
            - application_state
            - receive
            - send
            - accept
            - receive_text
            - receive_bytes
            - receive_json
            - iter_text

    我们将`SessionLocal()`请求的创建和处理放在一个`try`块中。

    然后我们在finally块中关闭它。

    通过这种方式，我们确保数据库会话在请求后始终关闭，即使在处理请求时出现异常也会关闭。

### 关于`request.state`

`request.state`是每个`Request`对象的属性。它用于存储附加到请求本身的任意对象，例如本例中的数据库会话。您可以在[Starlette 的关于`Request`state](https://www.starlette.io/requests/#other-state)的文档中了解更多信息。

对于这种情况下，它帮助我们确保在所有请求中使用单个数据库会话，然后关闭（在中间件中）。

### 使用`yield`依赖项与使用中间件的区别

在此处添加**中间件**与`yield`的依赖项的作用效果类似，但也有一些区别：

class ReviewNode(BaseModel):
    author: Union[Author, None] = None
    state: str


class Reviews(BaseModel):
    nodes: List[ReviewNode]


class PullRequestNode(BaseModel):
    number: int
    labels: Labels
    author: Union[Author, None] = None
    title: str
    createdAt: datetime
    state: str
    comments: Comments
    reviews: Reviews

class OtherDependencyError(Exception):
    pass


async def asyncgen_state(state: Dict[str, str] = Depends(get_state)):
    state["/async"] = "asyncgen started"
    yield state["/async"]
    state["/async"] = "asyncgen completed"


def generator_state(state: Dict[str, str] = Depends(get_state)):
    state["/sync"] = "generator started"
    yield state["/sync"]
    state["/sync"] = "generator completed"

                already_done_comment = comment
        logging.info(
            f"Already notified comment: {already_notified_comment}, already done comment: {already_done_comment}"
        )

        if pr.state == "open" and awaiting_label in label_strs:
            logging.info(
                f"This PR seems to be a language translation and awaiting reviews: #{pr.number}"
            )
            if already_notified_comment:

```Python
# db._state = PeeweeConnectionState()
```

And in the file `sql_app/main.py` file, comment the body of the `async` dependency `reset_db_state()` and replace it with a `pass`:

```Python
async def reset_db_state():
#     database.db._state._state.set(db_state_default.copy())
#     database.db._state.reset()
    pass
```

Then run your app with Uvicorn:

            - url
            - base_url
            - headers
            - query_params
            - path_params
            - cookies
            - client
            - state
            - url_for
            - client_state
            - application_state
            - receive
            - send
            - accept
            - receive_text
            - receive_bytes
            - receive_json
            - iter_text

    app.include_router(router)

    assert state.app_startup is False
    assert state.router_startup is False
    assert state.sub_router_startup is False
    assert state.app_shutdown is False
    assert state.router_shutdown is False
    assert state.sub_router_shutdown is False
    with TestClient(app) as client:
        assert state.app_startup is True
        assert state.router_startup is True

    return {"message": "OK"}


@pytest.fixture(autouse=True)
def reset_state_and_db():
    global fake_database
    global state
    fake_database = initial_fake_database.copy()
    state = initial_state.copy()


client = TestClient(app)


def test_dependency_gets_exception():
    assert state["except"] is False
    assert state["finally"] is False
    response = client.put("/invalid-user/rick", json="Morty")