That means that any value read in Python from an environment variable will be a `str`, and any conversion to a different type or any validation has to be done in code.

## Pydantic `Settings` { #pydantic-settings }

from typing import Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Union[str, None] = Query(
        default=None, min_length=3, max_length=50, pattern="^fixedquery$"
    ),
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

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


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


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

from datetime import datetime, time, timedelta
from uuid import UUID

from fastapi import Body, FastAPI

app = FastAPI()


@app.put("/items/{item_id}")
async def read_items(
    item_id: UUID,
    start_datetime: datetime = Body(),
    end_datetime: datetime = Body(),
    process_after: timedelta = Body(),
    repeat_at: time | None = Body(default=None),
):
    start_process = start_datetime + process_after

"""
Regression test, Error 422 if Form is declared before File
See https://github.com/tiangolo/fastapi/discussions/9116
"""

from pathlib import Path
from typing import Annotated

import pytest
from fastapi import FastAPI, File, Form
from fastapi.testclient import TestClient

app = FastAPI()


@app.post("/file_before_form")
def file_before_form(
    file: bytes = File(),
    city: str = Form(),
):

- [ ] Check ["Allow edit from maintainers" option](https://help.github.com/articles/allowing-changes-to-a-pull-request-branch-created-from-a-fork/) in pull request so that additional changes can be pushed by Gradle team.
- [ ] Provide integration tests (under `<subproject>/src/integTest`) to verify changes from a user perspective.
- [ ] Provide unit tests (under `<subproject>/src/test`) to verify logic.

            strategy.doApply(context, pomMap);

            // Verify version was removed (can be inferred from project)
            assertNull(DomUtils.findChildElement(dependency, "version"));
            // groupId should also be removed (can be inferred from project)
            assertNull(DomUtils.findChildElement(dependency, "groupId"));
            // artifactId should remain (always required)

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic import BaseModel

fake_users_db = {
    "johndoe": {
        "username": "johndoe",
        "full_name": "John Doe",
        "email": "******@****.***",
        "hashed_password": "fakehashedsecret",
        "disabled": False,
    },
    "alice": {

from dataclasses import dataclass, field
from typing import Union

from fastapi import FastAPI


@dataclass
class Item:
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: Union[str, None] = None
    tax: Union[float, None] = None


app = FastAPI()


@app.get("/items/next", response_model=Item)
async def read_next_item():
    return {
        "name": "Island In The Moon",

For example, if the **application server** is only receiving communication from the trusted **proxy**, you can set it to `--forwarded-allow-ips="*"` to make it trust all incoming IPs, as it will only receive requests from whatever is the IP used by the **proxy**.