from typing import Annotated, Literal

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

app = FastAPI()


class FilterParams(BaseModel):
    model_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/")

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

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": {

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


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


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[

import logging
import secrets
import subprocess
from pathlib import Path

import yaml
from github import Github
from pydantic import BaseModel, SecretStr
from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    github_repository: str
    github_token: SecretStr


class Repo(BaseModel):
    name: str
    html_url: str
    stars: int
    owner_login: str
    owner_html_url: str

     * This class handles the authentication, connection management, and data retrieval
     * from storage buckets and objects.
     *
     * <p>
     * The connection extracts bucket and object names from the URL and uses environment
     * variables for authentication and endpoint configuration.
     * </p>
     */

                        + "seems is an instance of '%s'",
                expression.subSequence(from, to), from, value.getClass());

        throw new IntrospectionException(message);
    }

    private static Object getIndexedValue(
            final String expression, final int from, final int to, final Object value, final String indexStr)
            throws IntrospectionException {
        try {

from typing import Union

from fastapi import FastAPI
from fastapi.responses import FileResponse
from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


responses = {
    404: {"description": "Item not found"},
    302: {"description": "The item was moved"},
    403: {"description": "Not enough privileges"},
}


app = FastAPI()


@app.get(
    "/items/{item_id}",

With this, we get tooling support, from editors and mypy as this code is correct in terms of types, but we also get the data filtering from FastAPI.

How does this work? Let's check that out. 🤓

### Type Annotations and Tooling { #type-annotations-and-tooling }

First let's see how editors, mypy and other tools would see this.

from pathlib import Path

from fastapi.testclient import TestClient

from docs_src.custom_response import tutorial009_py39
from docs_src.custom_response.tutorial009_py39 import app

client = TestClient(app)


def test_get(tmp_path: Path):
    file_path: Path = tmp_path / "large-video-file.mp4"
    tutorial009_py39.some_file_path = str(file_path)
    test_content = b"Fake video bytes"
    file_path.write_bytes(test_content)

from typing import Annotated, Union

from fastapi import Body, FastAPI, status
from fastapi.responses import JSONResponse

app = FastAPI()

items = {"foo": {"name": "Fighters", "size": 6}, "bar": {"name": "Tenders", "size": 3}}


@app.put("/items/{item_id}")
async def upsert_item(
    item_id: str,
    name: Annotated[Union[str, None], Body()] = None,
    size: Annotated[Union[int, None], Body()] = None,
):
    if item_id in items: