Commençons avec cette application pour exemple :

{* ../../docs_src/query_params_str_validations/tutorial001.py hl[9] *}

Le paramètre de requête `q` a pour type `Union[str, None]` (ou `str | None` en Python 3.10), signifiant qu'il est de type `str` mais pourrait aussi être égal à `None`, et bien sûr, la valeur par défaut est `None`, donc **FastAPI** saura qu'il n'est pas requis.

/// note

/// tip

This is just standard Python, it's called a "type alias", it's actually not specific to **FastAPI**.

But because **FastAPI** is based on the Python standards, including `Annotated`, you can use this trick in your code. 😎

///

                "item_id"
            ],
            "msg": "value is not a valid integer",
            "type": "type_error.integer"
        }
    ]
}
```

obtendrás una versión en texto, con:

```
1 validation error
path -> item_id
  value is not a valid integer (type=type_error.integer)
```

#### `RequestValidationError` vs `ValidationError`

/// warning | Advertencia

                "item_id"
            ],
            "msg": "value is not a valid integer",
            "type": "type_error.integer"
        }
    ]
}
```

você receberá a versão em texto:

```
1 validation error
path -> item_id
  value is not a valid integer (type=type_error.integer)
```

### `RequestValidationError` vs `ValidationError`

/// warning | Aviso

        enablePullRequestFeature()
    }

    requirements {
        requiresOs(os)
        requiresArch(os, arch)
    }

    failureConditions {
        if (this@applyDefaultSettings.type != BuildTypeSettings.Type.COMPOSITE) {
            executionTimeoutMin = timeout
        }
        testFailure = true
        supportTestRetry = true
        add {
            failOnText {

pkg log/slog, method (*MultiHandler) Handle(context.Context, Record) error #65954
pkg log/slog, method (*MultiHandler) WithAttrs([]Attr) Handler #65954
pkg log/slog, method (*MultiHandler) WithGroup(string) Handler #65954

tail -f ./fess-*/logs/*.log &

mvn test -P integrationTests -Dtest.fess.url="http://localhost:8080" -Dtest.search_engine.url="http://localhost:9201"
ret=$?

if [ $ret != 0 ] ; then
  for f in `find ./target -type f | grep surefire-reports | grep -v /TEST-` ; do
    cat $f
  done
fi

### Minor changes to the library {#minor_library_changes}

#### go/types

The `Var.Kind` method returns an enumeration of type `VarKind` that
classifies the variable (package-level, local, receiver, parameter,
result, or struct field). See issue #70250.

Callers of `NewVar` or `NewParam` are encouraged to call `Var.SetKind`

EyLTE5VDIzOjUzOjAxKzAxOjAw6tSWKgAAABl0RVh0U29mdHdhcmUAd3d3Lmlua3NjYXBlLm9yZ5vuPBoAAAAASUVORK5CYII=);-webkit-box-shadow:inset 0 1px 1px rgba(0,0,0,.075);box-shadow:inset 0 1px 1px rgba(0,0,0,.075)}input[type=file].error{color:#b94a48;background:0 0;-webkit-box-shadow:none;box-shadow:none}input[type=file].valid{color:#468847;background:0 0;-webkit-box-shadow:none;box-shadow:none}.form-error{display:block;color:#b94a48;margin-top:5px;margin-bottom:10px;line-height:140%}span.help{color:#999;font-siz...

Dependendo do seu caso de uso, você pode preferir usar uma biblioteca diferente, mas se você me perguntasse, eu provavelmente sugeriria que você experimentasse o **Strawberry**.