## `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:

from typing import List

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

app = FastAPI()


class FilterParams(BaseModel):
    class Config:
        extra = "forbid"

    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/")

	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 "Name":
			z.Name, err = dc.ReadString()

      throws IllegalAccessException {
    for (Field field : relevantFields(clazz)) {
      assertEquals(
          upperToHttpHeaderName(field.getName(), specialCases, uppercaseAcronyms), field.get(null));
    }
  }

  // Visible for other tests to use
  static ImmutableSet<Field> relevantFields(Class<?> cls) {
    ImmutableSet.Builder<Field> builder = ImmutableSet.builder();
    for (Field field : cls.getDeclaredFields()) {
      /*

                    "msg": "Field required",
                    "input": {"username": "Foo"},
                }
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1
        {
            "detail": [
                {
                    "loc": ["body", "password"],
                    "msg": "field required",
                    "type": "value_error.missing",

      throws IllegalAccessException {
    for (Field field : relevantFields(clazz)) {
      assertEquals(
          upperToHttpHeaderName(field.getName(), specialCases, uppercaseAcronyms), field.get(null));
    }
  }

  // Visible for other tests to use
  static ImmutableSet<Field> relevantFields(Class<?> cls) {
    ImmutableSet.Builder<Field> builder = ImmutableSet.builder();
    for (Field field : cls.getDeclaredFields()) {
      /*

from typing import Union

from fastapi import Depends, FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select


class Hero(SQLModel, table=True):
    id: Union[int, None] = Field(default=None, primary_key=True)
    name: str = Field(index=True)
    age: Union[int, None] = Field(default=None, index=True)
    secret_name: str


sqlite_file_name = "database.db"

    try {
      Field field = clazz.getDeclaredField(fieldName);
      return new FieldSetter<>(field);
    } catch (NoSuchFieldException e) {
      throw new AssertionError(e); // programmer error
    }
  }

  // Secret sauce for setting final fields; don't make it public.
  static final class FieldSetter<T> {
    private final Field field;

    private FieldSetter(Field field) {

func (z *LockArgs) 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 "UID":
			z.UID, err = dc.ReadString()

func (z *ChecksumInfo) 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 "PartNumber":
			z.PartNumber, err = dc.ReadInt()