app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item = Body(
        openapi_examples={
            "normal": {
                "summary": "A normal example",
                "description": "A **normal** item works correctly.",
                "value": {

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}")

app = FastAPI()


class BaseItem(BaseModel):
    description: str
    type: str


class CarItem(BaseItem):
    type: str = "car"


class PlaneItem(BaseItem):
    type: str = "plane"
    size: int


items = {
    "item1": {"description": "All my friends drive a low rider", "type": "car"},
    "item2": {
        "description": "Music is my aeroplane, it's my aeroplane",
        "type": "plane",

<?xml version="1.0" encoding="UTF-8"?>
<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/">
  <ShortName>Fess</ShortName>
  <Description>Full Text Search for Your Documents.</Description>
  <Tags>Full Text Search</Tags>
  <Contact>******@****.***</Contact>
  <SearchForm>http://localhost:8080/fess/</SearchForm>
  <Url type="text/html" template="http://localhost:8080/fess/search?q={searchTerms}"/>
  <InputEncoding>UTF-8</InputEncoding>

app = FastAPI()


def magic_data_reader(raw_body: bytes):
    return {
        "size": len(raw_body),
        "content": {
            "name": "Maaaagic",
            "price": 42,
            "description": "Just kiddin', no magic here. ✨",
        },
    }


@app.post(
    "/items/",
    openapi_extra={
        "requestBody": {
            "content": {
                "application/json": {

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        description: Annotated[
            str | None,
            Doc(
                """
                Security scheme description.

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,

      description: |
        We can remove packages with a shared path prefix.
        For example, a request for 'github.com/author' would remove all pkg.go.dev pages with that package path prefix.
    validations:
      required: true
  - type: textarea
    id: package-owner
    attributes:
      label: "Are you the owner of this package?"
      description: |

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:15] hl[14] *}

... dann ist das Feld `description` **nicht erforderlich**. Weil es den Defaultwert `None` hat.

### Eingabemodell in der Dokumentation { #input-model-in-docs }

Sie können überprüfen, dass das Feld `description` in der Dokumentation kein **rotes Sternchen** enthält, es ist nicht als erforderlich markiert:

<div class="screenshot">

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:15] hl[14] *}

…то поле `description` **не будет обязательным**, потому что у него значение по умолчанию `None`.

### Входная модель в документации { #input-model-in-docs }

В документации это видно: у поля `description` нет **красной звёздочки** — оно не отмечено как обязательное:

<div class="screenshot">

name: Go vulnerability management - bugs and feature requests
description: Issues or feature requests about Go vulnerability management
title: "x/vuln: issue title"
labels: ["vulncheck or vulndb"]
body:
  - type: markdown
    attributes: