/// tip

**GraphQL** solves some very specific use cases.

It has **advantages** and **disadvantages** when compared to common **web APIs**.

Make sure you evaluate if the **benefits** for your use case compensate the **drawbacks**. 🤓

///

## GraphQL Libraries { #graphql-libraries }

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

## Other data types { #other-data-types }

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

* `UUID`:
    * A standard "Universally Unique Identifier", common as an ID in many databases and systems.
    * In requests and responses will be represented as a `str`.

                "price": 50.5,
                "description": "Some Foo",
                "tax": 0.1,
            },
        },
    )
    assert response.status_code == 200
    assert response.json() == {
        "item_id": 5,
        "item": {
            "name": "Foo",
            "price": 50.5,
            "description": "Some Foo",
            "tax": 0.1,
        },
    }

If for some reason you need to disable automatic conversion of underscores to hyphens, set the parameter `convert_underscores` of `Header` to `False`:

{* ../../docs_src/header_params/tutorial002_an_py310.py hl[10] *}

/// warning

Before setting `convert_underscores` to `False`, bear in mind that some HTTP proxies and servers disallow the usage of headers with underscores.

///

# Advanced Python Types { #advanced-python-types }

Here are some additional ideas that might be useful when working with Python types.

## Using `Union` or `Optional` { #using-union-or-optional }

If your code for some reason can't use `|`, for example if it's not in a type annotation but in something like `response_model=`, instead of using the vertical bar (`|`) you can use `Union` from `typing`.

    * This is particularly important for **security**, we'll see more of that below.

## `response_model` Parameter { #response-model-parameter }

There are some cases where you need or want to return some data that is not exactly what the type declares.

* Be careful when using features introduced in Java 9 or later. Some parts of Gradle still need to run on Java 8.
* Normalize file paths in tests. The `org.gradle.util.internal.TextUtil` class has some useful functions for this purpose.

You can consult the [Architecture documentation](architecture) to learn about some of the architecture of Gradle.

```

...this would work:

```JSON
{
    "item_id": "foo-item",
    "needy": "sooooneedy"
}
```

And of course, you can define some parameters as required, some as having a default value, and some entirely optional:

{* ../../docs_src/query_params/tutorial006_py310.py hl[8] *}

In this case, there are 3 query parameters:

* `needy`, a required `str`.

    should not use them for communication between trusted and untrusted code.

6.  For the mainline flavor, we test the libraries using OpenJDK 8, 11, and 17
    on Linux, with some additional testing on newer JDKs and on Windows. Some
    features, especially in `com.google.common.io`, may not work correctly in
    non-Linux environments. For the Android flavor, our unit tests also run on
    API level 23 (Marshmallow).

```json
{
    "description": "Some data",
    "data": "aGVsbG8="
}
```

/// tip | Astuce

`aGVsbG8=` est l'encodage base64 de `hello`.

///

Pydantic décodera ensuite la chaîne base64 et vous fournira les octets originaux dans le champ `data` du modèle.

Vous recevrez une réponse comme :

```json
{
  "description": "Some data",
  "content": "hello"
}
```