{!> ../../docs_src/security/tutorial003_an.py!}
```

////

//// tab | Python 3.10+ non-Annotated

/// tip | Dica

Prefira usar a versão `Annotated`, se possível.

///

```Python hl_lines="2  74"
{!> ../../docs_src/security/tutorial003_py310.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip | Dica

Prefira usar a versão `Annotated`, se possível.

///

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str | None, Query(min_length=3)] = ...):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

## 响应模型编码参数

你的响应模型可以具有默认值，例如：

```Python hl_lines="11  13-14"
{!../../docs_src/response_model/tutorial004.py!}
```

* `description: Union[str, None] = None` 具有默认值 `None`。
* `tax: float = 10.5` 具有默认值 `10.5`.
* `tags: List[str] = []` 具有一个空列表作为默认值： `[]`.

但如果它们并没有存储实际的值，你可能想从结果中忽略它们的默认值。

举个例子，当你在 NoSQL 数据库中保存了具有许多可选属性的模型，但你又不想发送充满默认值的很长的 JSON 响应。

        {
            "detail": [
                {
                    "type": "missing",
                    "loc": ["body", "file"],
                    "msg": "Field required",
                    "input": None,
                }
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1
        {
            "detail": [
                {
                    "loc": ["body", "file"],

                Arguments.of(true, new String[] {"--force-interactive", "--non-interactive"}, false),
                Arguments.of(true, new String[] {"--force-interactive", "--batch-mode"}, false),
                Arguments.of(true, new String[] {"--force-interactive", "--non-interactive", "--batch-mode"}, false),
                Arguments.of(false, new String[] {"--non-interactive"}, true),

                DependencyScope.TEST.isTransitive(),
                byProjectPath(CommonBuilds.PROJECT_PATH_TEST)));
        result.add(internalScopeManager.createDependencyScope(
                DependencyScope.NONE.id(), DependencyScope.NONE.isTransitive(), Collections.emptySet()));
        result.add(internalScopeManager.createDependencyScope(
                DependencyScope.COMPILE_ONLY.id(),
                DependencyScope.COMPILE_ONLY.isTransitive(),

from typing import Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=..., min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[Union[str, None], Query(min_length=3)] = ...):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

    assert response.status_code == 200
    assert response.json() == {
        "host": "testserver",
        "save_data": True,
        "if_modified_since": None,
        "traceparent": None,
        "x_tag": [],
    }


def test_header_param_model_invalid(client: TestClient):
    response = client.get("/items/")
    assert response.status_code == 422

from typing import Union

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[Union[str, None], Query(min_length=3)] = ...):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})