from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(x_token: list[str] | None = Header(default=None)):

from fastapi import FastAPI
from fastapi.testclient import TestClient
from inline_snapshot import snapshot

app = FastAPI()


@app.get("/", openapi_extra={"x-custom-extension": "value"})
def route_with_extras():
    return {}


client = TestClient(app)


def test_get_route():
    response = client.get("/")
    assert response.status_code == 200, response.text
    assert response.json() == {}

# Doğrudan Bir Response Döndürme { #return-a-response-directly }

**FastAPI** ile bir *path operation* oluşturduğunuzda, normalde ondan herhangi bir veri döndürebilirsiniz: bir `dict`, bir `list`, bir Pydantic model, bir veritabanı modeli vb.

Bir [Response Model](../tutorial/response-model.md) deklare ederseniz, FastAPI veriyi Pydantic kullanarak JSON'a serialize etmek için bunu kullanır.

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI(swagger_ui_oauth2_redirect_url=None)


@app.get("/items/")
async def read_items():
    return {"id": "foo"}


client = TestClient(app)


def test_swagger_ui():
    response = client.get("/docs")
    assert response.status_code == 200, response.text
    assert response.headers["content-type"] == "text/html; charset=utf-8"

from fastapi import FastAPI
from fastapi.responses import RedirectResponse

app = FastAPI()


@app.get("/fastapi", response_class=RedirectResponse)
async def redirect_fastapi():

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: list[str] = Query(default=["foo", "bar"])):
    query_items = {"q": q}

from fastapi import FastAPI, Request

app = FastAPI(root_path="/api/v1")


@app.get("/app")
def read_main(request: Request):

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/")
async def read_main():
    return {"msg": "Hello World"}


client = TestClient(app)


def test_read_main():
    response = client.get("/")
    assert response.status_code == 200

因此，**FastAPI** 会负责过滤掉输出模型中未声明的所有数据（使用 Pydantic）。

### `response_model` 还是返回类型 { #response-model-or-return-type }

在这个例子中，因为两个模型不同，如果我们将函数返回类型注解为 `UserOut`，编辑器和工具会抱怨我们返回了无效类型，因为它们是不同的类。

这就是为什么在这个例子里我们必须在 `response_model` 参数中声明它。

……但继续往下读，看看如何更好地处理这种情况。

## 返回类型与数据过滤 { #return-type-and-data-filtering }

延续上一个例子。我们希望**用一种类型来注解函数**，但希望从函数返回的内容实际上可以**包含更多数据**。

package clause

type Delete struct {
	Modifier string
}

func (d Delete) Name() string {
	return "DELETE"
}

func (d Delete) Build(builder Builder) {
	builder.WriteString("DELETE")

	if d.Modifier != "" {
		builder.WriteByte(' ')
		builder.WriteString(d.Modifier)
	}
}

func (d Delete) MergeClause(clause *Clause) {
	clause.Name = ""
	clause.Expression = d