A primeira coisa a notar é que estamos definindo uma função assíncrona com `yield`. Isso é muito semelhante a Dependências com `yield`.

{* ../../docs_src/events/tutorial003_py310.py hl[14:19] *}

A primeira parte da função, antes do `yield`, será executada **antes** de a aplicação iniciar.

E a parte posterior ao `yield` será executada **depois** de a aplicação ter terminado.

        // Assert using reflection to verify superclass fields
        Field handleField = lsarpc.LsarLookupSids.class.getDeclaredField("handle");
        handleField.setAccessible(true);
        assertSame(mockPolicyHandle, handleField.get(lookupSids));

        Field countField = lsarpc.LsarLookupSids.class.getDeclaredField("count");
        countField.setAccessible(true);

/// tip | 팁

비동기 함수 안에서 블로킹 코드를 호출해야 하거나, 반대로 블로킹 함수 안에서 비동기 함수를 호출해야 한다면 FastAPI의 형제 라이브러리인 [Asyncer](https://asyncer.tiangolo.com)를 사용할 수 있습니다.

///

### `yield from` { #yield-from }

파일 유사 객체처럼 어떤 것을 순회하면서 각 항목마다 `yield`를 하는 대신, `yield from`을 사용해 각 항목을 직접 전달하고 `for` 루프를 생략할 수 있습니다.

이는 FastAPI에 특화된 기능이 아니라 순수한 파이썬 기능이지만, 알아두면 유용한 트릭입니다. 😎

async def stream_items() -> AsyncIterable[Item]:
    for item in items:
        yield item


@app.get("/items/stream-no-async")
def stream_items_no_async() -> Iterable[Item]:
    for item in items:
        yield item


@app.get("/items/stream-no-annotation")
async def stream_items_no_annotation():
    for item in items:
        yield item


@app.get("/items/stream-no-async-no-annotation")

from typing import Literal

from fastapi import FastAPI, Query
from pydantic import BaseModel, Field

app = FastAPI()


class FilterParams(BaseModel):
    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")
async def read_items(filter_query: FilterParams = Query()):

    assert response.status_code == 422
    assert response.json() == {
        "detail": [
            {
                "type": "missing",
                "loc": ["body", "p"],
                "msg": "Field required",
                "input": None,
            }
        ]
    }


@pytest.mark.parametrize(
    "path",
    [
        "/required-bytes",
        "/required-uploadfile",
    ],
)

    private Object getFieldValue(Object obj, String fieldName) {
        try {
            Field field = getField(obj.getClass(), fieldName);
            field.setAccessible(true);
            return field.get(obj);
        } catch (Exception e) {
            throw new RuntimeException("Failed to get field value: " + fieldName, e);
        }
    }

     */
    void init() throws IOException;

    /**
     * Converts the given text into a list of readings based on the specified field and languages.
     *
     * @param text the text to be converted.
     * @param field the field to be used for conversion.
     * @param langs the languages to be used for conversion.
     * @return a list of readings for the given text.

    // --------------------------/
    // - Class/Member Variables -/
    // --------------------------/

    /**
     * Field extensions.
     */
    private List<CoreExtension> extensions;

    /**
     * Field modelEncoding.
     */
    private String modelEncoding = "UTF-8";

    // -----------/
    // - Methods -/
    // -----------/

    /**

from fastapi import Depends


async def dependency_a():
    dep_a = generate_dep_a()
    try:
        yield dep_a
    finally:
        dep_a.close()


async def dependency_b(dep_a: Annotated[DepA, Depends(dependency_a)]):
    dep_b = generate_dep_b()
    try:
        yield dep_b
    finally:
        dep_b.close(dep_a)


async def dependency_c(dep_b: Annotated[DepB, Depends(dependency_b)]):