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

这是因为路径参数 `item_id` 的值 （`"foo"`）的类型不是 `int`。

值的类型不是 `int ` 而是浮点数（`float`）时也会显示同样的错误，比如： <a href="http://127.0.0.1:8000/items/4.2" class="external-link" target="_blank">http://127.0.0.1:8000/items/4.2。</a>

/// check | 检查

**FastAPI** 使用 Python 类型声明实现了数据校验。

注意，上面的错误清晰地指出了未通过校验的具体原因。

      "input": "foo"
    }
  ]
}
```

porque o parâmetro de path `item_id` tinha o valor `"foo"`, que não é um `int`.

O mesmo erro apareceria se você fornecesse um `float` em vez de um `int`, como em: <a href="http://127.0.0.1:8000/items/4.2" class="external-link" target="_blank">http://127.0.0.1:8000/items/4.2</a>

/// check | Verifique

Diese **„Typhinweise“** oder -Annotationen sind eine spezielle Syntax, die es erlaubt, den <abbr title="zum Beispiel: str, int, float, bool">Typ</abbr> einer Variablen zu deklarieren.

Durch das Deklarieren von Typen für Ihre Variablen können Editoren und Tools bessere Unterstützung bieten.

```Python hl_lines="4  9-12  25-27"
from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):

         * Sets the weight for the request data.
         *
         * @param weight the weight to set
         * @return the current RequestDataContext instance
         */
        public RequestDataContext weight(final float weight) {
            data.setWeight(weight);
            return this;
        }

        /**
         * Builds and returns the constructed RequestData object.
         *

                            <la:message key="labels.dict_stemmeroverride_title"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/dict">
                                <la:message key="labels.dict_list_link"/>
                            </la:link></li>

                            <la:message key="labels.wizard_title_configuration"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item active"><la:link href="/admin/wizard/">
                                <la:message key="labels.wizard_start_title"/>
                            </la:link></li>

    // The values here look like 111...11101...010 in binary, where the initial 111...1110 takes
    // up exactly as many bits as can be represented in the significand (24 for float, 53 for
    // double). That final 0 should be rounded up to 1 because the remaining bits make that number
    // slightly nearer.
    long floatConversionTest = 0xfffffe8000000002L;

# Introduction aux Types Python

Python supporte des annotations de type (ou *type hints*) optionnelles.

Ces annotations de type constituent une syntaxe spéciale qui permet de déclarer le <abbr title="par exemple : str, int, float, bool">type</abbr> d'une variable.

En déclarant les types de vos variables, cela permet aux différents outils comme les éditeurs de texte d'offrir un meilleur support.

from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

bearer_scheme = HTTPBearer()


class Subscription(BaseModel):
    username: str
    monthly_fee: float
    start_date: datetime


@app.webhooks.post("new-subscription")
def new_subscription(
    body: Subscription, token: Annotated[str, Security(bearer_scheme)]
):
    """