## 使用回调的应用

示例如下。

假设要开发一个创建发票的应用。

发票包括 `id`、`title`（可选）、`customer`、`total` 等属性。

API 的用户 （外部开发者）要在您的 API 内使用 POST 请求创建一条发票记录。

（假设）您的 API 将：

* 把发票发送至外部开发者的消费者
* 归集现金
* 把通知发送至 API 的用户（外部开发者）
    * 通过（从您的 API）发送 POST 请求至外部 API （即**回调**）来完成

## 常规 **FastAPI** 应用

添加回调前，首先看下常规 API 应用是什么样子。

常规 API 应用包含接收 `Invoice` 请求体的*路径操作*，还有包含回调 URL 的查询参数 `callback_url`。

        yield session


SessionDep = Annotated[Session, Depends(get_session)]

app = FastAPI()


@app.on_event("startup")
def on_startup():
    create_db_and_tables()


@app.post("/heroes/")
def create_hero(hero: Hero, session: SessionDep) -> Hero:
    session.add(hero)
    session.commit()
    session.refresh(hero)
    return hero


@app.get("/heroes/")
def read_heroes(

from docs_src.background_tasks.tutorial001_py39 import app

client = TestClient(app)


def test():
    log = Path("log.txt")
    if log.is_file():
        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Notification sent in the background"}
    with open("./log.txt") as f:

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()


@app.post("/items/", response_model=Item, tags=["items"])
async def create_item(item: Item):
    return item


@app.get("/items/", tags=["items"])
async def read_items():
    return [{"name": "Foo", "price": 42}]

	}
	if len(s) > len(b) {
		f.ops[0] = s[len(b):]
	} else {
		f.ops = f.ops[1:]
	}
	f.pos += int64(len(b))
	return len(b), nil
}

func (f *testFile) Seek(pos int64, whence int) (int64, error) {
	if pos == 0 && whence == io.SeekCurrent {
		return f.pos, nil
	}
	if len(f.ops) == 0 {
		return 0, errors.New("unexpected Seek operation")
	}
	s, ok := f.ops[0].(int64)
	if !ok {

* `@app.get()`
* `@app.post()`
* `@app.put()`
* `@app.delete()`
* etc.

{* ../../docs_src/response_status_code/tutorial001_py39.py hl[6] *}

/// note | Nota

Observe que `status_code` é um parâmetro do método "decorador" (`get`, `post`, etc). Não da sua função de *operação de rota*, como todos os parâmetros e corpo.

///

sources | indent 10 }} {{- end }} minio/templates/post-install-create-user-job.yaml {{- if .Values.users }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-make-user-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-make-user-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook": post-install,post-upgrade "helm.sh/hook-delete-policy": hook-succee...

sources | indent 10 }} {{- end }} minio/templates/post-install-create-user-job.yaml {{- if .Values.users }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-make-user-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-make-user-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook": post-install,post-upgrade "helm.sh/hook-delete-policy": hook-succee...

sources | indent 10 }} {{- end }} minio/templates/post-install-create-user-job.yaml {{- if .Values.users }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-make-user-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-make-user-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook": post-install,post-upgrade "helm.sh/hook-delete-policy": hook-succee...

* `@app.get()`
* `@app.post()`
* `@app.put()`
* `@app.delete()`
* тощо.

{* ../../docs_src/response_status_code/tutorial001.py hl[6] *}

/// note | Нотатка

Зверніть увагу, що `status_code` є параметром методу "декоратора" (`get`, `post` і т.д.), а не Вашої *функції операції шляху*, як усі інші параметри та тіло запиту.

///