与在*路径操作函数*中使用 `Query`、`Path` 、`Body` 声明校验与元数据的方式一样，可以使用 Pydantic 的 `Field` 在 Pydantic 模型内部声明校验和元数据。

## 导入 `Field`

首先，从 Pydantic 中导入 `Field`：

=== "Python 3.10+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

## Importe `Field`

Primeiro, você tem que importá-lo:

```Python hl_lines="4"
{!../../../docs_src/body_fields/tutorial001.py!}
```

!!! warning "Aviso"
    Note que `Field` é importado diretamente do `pydantic`, não do `fastapi` como todo o resto (`Query`, `Path`, `Body`, etc).

	user, err := schema.Parse(&UserWithPermissionControl{}, &sync.Map{}, schema.NamingStrategy{})
	if err != nil {
		t.Fatalf("Failed to parse user with permission, got error %v", err)
	}

	fields := []*schema.Field{
		{Name: "ID", DBName: "id", BindNames: []string{"ID"}, DataType: schema.Uint, PrimaryKey: true, Size: 64, Creatable: true, Updatable: true, Readable: true, HasDefaultValue: true, AutoIncrement: true},

## `Field`のインポート

まず、以下のようにインポートします:

```Python hl_lines="4"
{!../../../docs_src/body_fields/tutorial001.py!}
```

!!! warning "注意"
    `Field`は他の全てのもの（`Query`、`Path`、`Body`など）とは違い、`fastapi`からではなく、`pydantic`から直接インポートされていることに注意してください。

## モデルの属性の宣言

以下のように`Field`をモデルの属性として使用することができます:

```Python hl_lines="11 12 13 14"

	if cc2.Name != "bar" {
		t.Errorf("Failed to query CustomizeColumn")
	}
}

func TestCustomColumnAndIgnoredFieldClash(t *testing.T) {
	// Make sure an ignored field does not interfere with another field's custom
	// column name that matches the ignored field.
	type CustomColumnAndIgnoredFieldClash struct {
		Body    string `gorm:"-"`
		RawBody string `gorm:"column:body"`
	}

and <code>T</code> itself may not be
a pointer type. The unqualified type name acts as the field name.
</p>

<pre>
// A struct with four embedded fields of types T1, *T2, P.T3 and *P.T4
struct {
	T1        // field name is T1
	*T2       // field name is T2
	P.T3      // field name is T3
	*P.T4     // field name is T4
	x, y int  // field names are x and y
}
</pre>

<p>

from .utils import needs_pydanticv2


@pytest.fixture(name="client")
def get_client():
    app = FastAPI()

    from pydantic import BaseModel, computed_field

    class Rectangle(BaseModel):
        width: int
        length: int

        @computed_field
        @property
        def area(self) -> int:
            return self.width * self.length

    @app.get("/")
    def read_root() -> Rectangle:

and <code>T</code> itself may not be
a pointer type. The unqualified type name acts as the field name.
</p>

<pre>
// A struct with four embedded fields of types T1, *T2, P.T3 and *P.T4
struct {
	T1        // field name is T1
	*T2       // field name is T2
	P.T3      // field name is T3
	*P.T4     // field name is T4
	x, y int  // field names are x and y
}
</pre>

<p>

	}

	animal = Animal{From: "somewhere"}              // No name fields, should be filled with the default value (galeone)
	DB.Save(&animal).Update("From", "a nice place") // The name field shoul be untouched
	DB.First(&animal, animal.Counter)
	if animal.Name != "galeone" {
		t.Errorf("Name fields shouldn't be changed if untouched, but got %v", animal.Name)
	}

	// When changing a field with a default value, the change must occur

Und dann basierte das neue OpenAPI 3.1.0 auf der neuesten Version (JSON Schema 2020-12), die dieses neue Feld `examples` enthielt.

Und jetzt hat dieses neue `examples`-Feld Vorrang vor dem alten (und benutzerdefinierten) `example`-Feld, im Singular, das jetzt deprecated ist.