```Python
q: Annotated[str | None, Query(min_length=3)] = None
```

So, when you need to declare a value as required while using `Query`, you can simply not declare a default value:

{* ../../docs_src/query_params_str_validations/tutorial006_an_py310.py hl[9] *}

### Required, can be `None` { #required-can-be-none }

Hug ajudou a inspirar o **FastAPI** a usar anotações de tipo do Python para declarar parâmetros e para gerar um schema definindo a API automaticamente.

Hug inspirou **FastAPI** a declarar um parâmetro de `response` em funções para definir cabeçalhos e cookies.

///

### [APIStar](https://github.com/encode/apistar) (<= 0.5) { #apistar-0-5 }

Par exemple, vous pourriez déclarer que quelque chose peut être un `str` ou `None` :

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

`typing` propose également un raccourci pour déclarer que quelque chose peut être `None`, avec `Optional`.

ps-of-path-operations }

Más adelante, al leer sobre cómo estructurar aplicaciones más grandes ([Aplicaciones Más Grandes - Múltiples Archivos](../../tutorial/bigger-applications.md)), posiblemente con múltiples archivos, aprenderás cómo declarar un solo parámetro de `dependencies` para un grupo de *path operations*....

   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}, all non-private instance methods will be checked too using the instance
   *       created by invoking the constructor or static factory method.
   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}:
   *       <ul>

Se você declarar o tipo de retorno como `AsyncIterable[Item]`, o FastAPI o usará para validar, documentar e serializar os dados com o Pydantic.

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[1:25] hl[10:12,23] *}

/// tip | Dica

Como o Pydantic fará a serialização no lado em **Rust**, você terá um desempenho muito maior do que se não declarar um tipo de retorno.

///

          // Since this is an artificially generated type variable, we don't bother checking
          // subtyping between declared type bound and actual type bound. So it's possible that we
          // may generate something like <capture#1-of ? extends Foo&SubFoo>.
          // Checking subtype between declared and actual type bounds
          // adds recursive isSubtypeOf() call and feels complicated.

///

### Importer `Depends` { #import-depends }

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[3] *}

### Déclarer la dépendance, dans le « dependant » { #declare-the-dependency-in-the-dependant }

De la même manière que vous utilisez `Body`, `Query`, etc. avec les paramètres de votre fonction de chemin d’accès, utilisez `Depends` avec un nouveau paramètre :

You can also declare singular values to be received as part of the body.

   *       AbstractPackageSanityTests} doesn't know how to construct, the test will fail.
   *   <li>If there is no visible constructor or visible static factory method declared by {@code
   *       C}, {@code C} is skipped for serialization test, even if it implements {@link
   *       Serializable}.
   *   <li>Serialization test is not performed on method return values unless the method is a