Les schémas sont référencés à un autre endroit du modèle OpenAPI :

```JSON hl_lines="4-16"
{
    "components": {
        "schemas": {
            "Message": {
                "title": "Message",
                "required": [
                    "message"
                ],
                "type": "object",
                "properties": {
                    "message": {
                        "title": "Message",

### ⚙️ Pydantic `Required` ↩️ ❕ (`...`)

🚥 👆 💭 😬 ⚙️ `...`, 👆 💪 🗄 & ⚙️ `Required` ⚪️➡️ Pydantic:

```Python hl_lines="2  8"
{!../../../docs_src/query_params_str_validations/tutorial006d.py!}
```

!!! tip

It requires a little bit more verbose configurations. And as it is based on WSGI (instead of ASGI), it is not designed to take advantage of the high performance provided by tools like Uvicorn, Starlette and Sanic.

!!! note
    **FastAPI** saura que la valeur de `q` n'est pas requise grâce à la valeur par défaut `= None`.

    Le `Union` dans `Union[str, None]` permettra à votre éditeur de vous offrir un meilleur support et de détecter les erreurs.

## Validation additionnelle

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

=== "Python 3.10+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py310/main.py!}
    ```

=== "Python 3.9+"

    ```Python

```TypeScript
ItemsService.createItemItemsPost({name: "Plumbus", price: 5})
```

...that's because the client generator uses the OpenAPI internal **operation ID** for each *path operation*.

It can contain several fields. <details><summary><code>license_info</code> fields</summary><table><thead><tr><th>Parameter</th><th>Type</th><th>Description</th></tr></thead><tbody><tr><td><code>name</code></td><td><code>str</code></td><td><strong>REQUIRED</strong> (if a <code>license_info</code> is set). The license name used for the API.</td></tr><tr><td><code>identifier</code></td><td><code>str</code></td><td>An <a href="https://spdx.org/licenses/" class="external-link" target="_blank">SPDX</a>...

        }
    }
}

```
**模式被引用到OpenAPI模式中的另一个位置：**
```json hl_lines="4-16"
{
    "components": {
        "schemas": {
            "Message": {
                "title": "Message",
                "required": [
                    "message"
                ],
                "type": "object",
                "properties": {
                    "message": {
                        "title": "Message",

### 使用Pydantic中的`Required`代替省略号(`...`)

如果你觉得使用 `...` 不舒服，你也可以从 Pydantic 导入并使用 `Required`：

```Python hl_lines="2  8"
{!../../../docs_src/query_params_str_validations/tutorial006d.py!}
```

!!! tip

## Type Hints with Metadata Annotations

Python also has a feature that allows putting **additional metadata** in these type hints using `Annotated`.