from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: list[str] = []


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

from typing import 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: FilterParams = Query()):

Сначала вы должны импортировать его:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}

/// warning | Внимание

Обратите внимание, что функция `Field` импортируется непосредственно из `pydantic`, а не из `fastapi`, как все остальные функции (`Query`, `Path`, `Body` и т.д.).

///

## Объявление атрибутов модели { #declare-model-attributes }

Вы можете использовать функцию `Field` с атрибутами модели:

import importlib

import pytest
from fastapi.testclient import TestClient
from inline_snapshot import snapshot

from tests.utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial002_py39"),
        pytest.param("tutorial002_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.dataclasses_.{request.param}")

from fastapi.testclient import TestClient

from docs_src.events.tutorial003_py39 import (
    app,
    fake_answer_to_everything_ml_model,
    ml_models,
)


def test_events():
    assert not ml_models, "ml_models should be empty"
    with TestClient(app) as client:
        assert ml_models["answer_to_everything"] == fake_answer_to_everything_ml_model
        response = client.get("/predict", params={"x": 2})

from fastapi.testclient import TestClient

from docs_src.response_model.tutorial003_02_py39 import app

client = TestClient(app)


def test_get_portal():
    response = client.get("/portal")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Here's your interdimensional portal."}


def test_get_redirect():
    response = client.get("/portal", params={"teleport": True}, follow_redirects=False)

import importlib

import pytest
from fastapi.testclient import TestClient


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial001_py39"),
        pytest.param("tutorial002_py39"),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.response_status_code.{request.param}")

    client = TestClient(mod.app)
    return client

Por ejemplo, si quieres leer o manipular el request body antes de que sea procesado por tu aplicación.

/// danger | Advertencia

Esta es una funcionalidad "avanzada".

Si apenas estás comenzando con **FastAPI**, quizás quieras saltar esta sección.

///

## Casos de uso { #use-cases }

Algunos casos de uso incluyen:

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel


class Item(BaseModel):
    name: str
    description: Optional[str] = None


app = FastAPI(separate_input_output_schemas=False)


@app.post("/items/")
def create_item(item: Item):
    return item


@app.get("/items/")
def read_items() -> list[Item]:
    return [
        Item(
            name="Portal Gun",

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Image(BaseModel):
    url: str
    name: str


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()
    image: Image | None = None


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