Sie können dies in der Dokumentations-UI unter `/docs` testen:

<div class="screenshot">
<img src="/img/tutorial/request-form-models/image01.png">
</div>

## Zusätzliche Formularfelder verbieten { #forbid-extra-form-fields }

from typing import Annotated, Literal

from fastapi import FastAPI, Query
from pydantic import BaseModel, Field

app = FastAPI()


class FilterParams(BaseModel):
    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")
async def read_items(filter_query: Annotated[FilterParams, Query()]):

                    public String @Nullable [] foo() { return new String[] {"some", null}; }
                }
            """
        ) {
            assertHasErrors(
                "Field nonFinalField: Nullability breaking change.",
                "Field finalField: From non-nullable to nullable breaking change.",
                "Method com.example.Source.foo(): From non-null returning to null returning breaking change."
            )

## Campos do tipo Lista { #list-fields }

Você pode definir um atributo como um subtipo. Por exemplo, uma `list` do Python:

{* ../../docs_src/body_nested_models/tutorial001_py310.py hl[12] *}

Isso fará com que tags seja uma lista de itens mesmo sem declarar o tipo dos elementos desta lista.

## Campos do tipo Lista com um parâmetro de tipo { #list-fields-with-type-parameter }

@dataclass
class Dependant:
    path_params: list[ModelField] = field(default_factory=list)
    query_params: list[ModelField] = field(default_factory=list)
    header_params: list[ModelField] = field(default_factory=list)
    cookie_params: list[ModelField] = field(default_factory=list)
    body_params: list[ModelField] = field(default_factory=list)
    dependencies: list["Dependant"] = field(default_factory=list)
    name: Optional[str] = None

func (z *WalkDirOptions) DecodeMsg(dc *msgp.Reader) (err error) {
	var field []byte
	_ = field
	var zb0001 uint32
	zb0001, err = dc.ReadMapHeader()
	if err != nil {
		err = msgp.WrapError(err)
		return
	}
	for zb0001 > 0 {
		zb0001--
		field, err = dc.ReadMapKeyPtr()
		if err != nil {
			err = msgp.WrapError(err)
			return
		}
		switch msgp.UnsafeString(field) {
		case "Bucket":
			z.Bucket, err = dc.ReadString()

                                "` structure with `struct_size` field "   \
                                "set to " #SIZE_VALUE_NAME                \
                                ". Found `struct_size` = 0.");            \
    }                                                                     \
  } while (0)

// Macro to verify that the field NAME of STRUCT_OBJ is not null.

                    "body",
                    "item",
                ],
                "msg": "Field required",
                "type": "missing",
            },
            {
                "input": None,
                "loc": [
                    "body",
                    "user",
                ],
                "msg": "Field required",
                "type": "missing",
            },
        ],
    }

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: float | None = None


@app.put("/items/{item_id}")

    // --------------------------/
    // - Class/Member Variables -/
    // --------------------------/

    /**
     * Field extensions.
     */
    private List<CoreExtension> extensions;

    /**
     * Field modelEncoding.
     */
    private String modelEncoding = "UTF-8";

    // -----------/
    // - Methods -/
    // -----------/

    /**