from contextlib import asynccontextmanager

from fastapi import FastAPI


def fake_answer_to_everything_ml_model(x: float):
    return x * 42


ml_models = {}


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Load the ML model
    ml_models["answer_to_everything"] = fake_answer_to_everything_ml_model
    yield
    # Clean up the ML models and release the resources
    ml_models.clear()

from contextlib import asynccontextmanager

from fastapi import FastAPI
from fastapi.testclient import TestClient

items = {}


@asynccontextmanager
async def lifespan(app: FastAPI):
    items["foo"] = {"name": "Fighters"}
    items["bar"] = {"name": "Tenders"}
    yield
    # clean up items
    items.clear()


app = FastAPI(lifespan=lifespan)


@app.get("/items/{item_id}")
async def read_items(item_id: str):

    lenient_issubclass,
    sequence_types,
    serialize_sequence_value,
    value_is_sequence,
)
from fastapi.background import BackgroundTasks
from fastapi.concurrency import (
    asynccontextmanager,
    contextmanager_in_threadpool,
)
from fastapi.dependencies.models import Dependant
from fastapi.exceptions import DependencyScopeError
from fastapi.logger import logger

Cualquier función que sea válida para usar con:

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) o
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

sería válida para usar como una dependencia en **FastAPI**.

De hecho, FastAPI usa esos dos decoradores internamente.

///

Any function that is valid to use with:

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) or
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

would be valid to use as a **FastAPI** dependency.

In fact, FastAPI uses those two decorators internally.

///

///

/// note | 技術細節

任何可用於下列裝飾器的函式：

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) 或
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

都可以作為 **FastAPI** 的相依。

事實上，FastAPI 內部就是使用這兩個裝飾器。

///

## 使用 `yield` 的資料庫相依 { #a-database-dependency-with-yield }

例如，你可以用它建立一個資料庫 session，並在完成後關閉。

Qualquer função que possa ser utilizada com:

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) ou
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

pode ser utilizada como uma dependência do **FastAPI**.

Na realidade, o FastAPI utiliza esses dois decoradores internamente.

///

Любая функция, с которой можно корректно использовать:

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) или
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

будет корректной для использования в качестве зависимости **FastAPI**.

На самом деле, FastAPI использует эти два декоратора внутренне.

///

Jede Funktion, die dekoriert werden kann mit:

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) oder
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

kann auch als gültige **FastAPI**-Abhängigkeit verwendet werden.

Tatsächlich verwendet FastAPI diese beiden Dekoratoren intern.

///

/// note | 기술 세부사항

다음과 함께 사용할 수 있는 모든 함수:

* [`@contextlib.contextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager) 또는
* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

는 **FastAPI**의 의존성으로 사용할 수 있습니다.

사실, FastAPI는 내부적으로 이 두 데코레이터를 사용합니다.

///

## `yield`를 사용하는 데이터베이스 의존성 { #a-database-dependency-with-yield }