```

## Recap

With `Query`, `Path` (and others you haven't seen yet) you can declare metadata and string validations in the same ways as with [Query Parameters and String Validations](query-params-str-validations.md){.internal-link target=_blank}.

And you can also declare numeric validations:

* `gt`: `g`reater `t`han
* `ge`: `g`reater than or `e`qual
* `lt`: `l`ess `t`han
* `le`: `l`ess than or `e`qual

But you can also use more complex data types.

And you will still have the same features as seen up to now:

* Great editor support.
* Data conversion from incoming requests.
* Data conversion for response data.
* Data validation.
* Automatic annotation and documentation.

## Other data types

Here are some of the additional data types you can use:

* `UUID`:

So, even with the code above that doesn't use Pydantic explicitly, FastAPI is using Pydantic to convert those standard dataclasses to Pydantic's own flavor of dataclasses.

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

!!! info

    ```

## Declare `Header` parameters

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

The first value is the default value, you can pass all the extra validation or annotation parameters:

=== "Python 3.10+"

    ```Python hl_lines="9"
    {!> ../../../docs_src/header_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="9"

            dependencies {
                implementation(kotlin("stdlib"))
            }

            ${if (kotlinVersion >= VersionNumber.parse("1.9.0")) {
                """
                // Work around JVM validation issue: https://youtrack.jetbrains.com/issue/KT-66919
                tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {

* Editor support (obviously)
* Data <abbr title="converting the string that comes from an HTTP request into Python data">"parsing"</abbr>
* Data validation
* Automatic documentation

## Defaults

As query parameters are not a fixed part of a path, they can be optional and can have default values.

<img src="https://fastapi.tiangolo.com/img/tutorial/body-fields/image01.png">

## 技術詳細

`example` と `examples`について...

JSON Schemaの最新バージョンでは<a href="https://json-schema.org/draft/2019-09/json-schema-validation.html#rfc.section.9.5" class="external-link" target="_blank">`examples`</a>というフィールドを定義していますが、OpenAPIは`examples`を持たない古いバージョンのJSON Schemaをベースにしています。

& 👈 **🎻 🔗** Pydantic 🏷 🔌 **🗄** 👆 🛠️, & ⤴️ ⚫️ ⚙️ 🩺 🎚.

**🎻 🔗** 🚫 🤙 ✔️ 🏑 `example` 🐩. ⏮️ ⏬ 🎻 🔗 🔬 🏑 <a href="https://json-schema.org/draft/2019-09/json-schema-validation.html#rfc.section.9.5" class="external-link" target="_blank">`examples`</a>, ✋️ 🗄 3️⃣.0️⃣.3️⃣ ⚓️ 🔛 🗝 ⏬ 🎻 🔗 👈 🚫 ✔️ `examples`.

                    "schema": {
                        "$ref": "#/components/schemas/Item"
                    }
                }
            }
        },
        "422": {
            "description": "Validation Error",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/HTTPValidationError"
                    }
                }

* Support de l'éditeur : vérification d'erreurs, auto-complétion, etc.
* <abbr title="conversion de la chaîne de caractères venant de la requête HTTP en données Python">"Parsing"</abbr> de données.
* Validation de données.
* Annotations d'API et documentation automatique.

## Valeurs par défaut

Les paramètres de requête ne sont pas une partie fixe d'un chemin, ils peuvent être optionnels et avoir des valeurs par défaut.