@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            }
        ],
    ),
):
    results = {"item_id": item_id, "item": item}

async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ],
        ),
    ],
):
    results = {"item_id": item_id, "item": item}

@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            },
            {
                "name": "Bar",
                "price": "35.4",
            },
            {

async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                },
                {
                    "name": "Bar",
                    "price": "35.4",
                },

    price: float
    tax: float | None = None

    class Config:
        schema_extra = {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]
        }


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):

                    "description": "A **normal** item works correctly.",
                    "value": {
                        "name": "Foo",
                        "description": "A very nice Item",
                        "price": 35.4,
                        "tax": 3.2,
                    },
                },
                "converted": {

from fastapi import FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):

    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {
            "title": "Custom title",
            "summary": "This is a very custom OpenAPI schema",
            "description": "Here's a longer description of the custom **OpenAPI** schema",
            "version": "2.5.0",
            "x-logo": {

This can be reading from Kubernetes and writing other objects back, writing to proxies over XDS, etc.

Unfortunately, writing controllers is very error prone, even for seemingly simple cases.
To work around this, Istio has a variety of abstractions meant to make writing controllers easier.

## Clients

@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            },
            {
                "name": "Bar",
                "price": "35.4",
            },
            {