from fastapi import Body, FastAPI
from pydantic import BaseModel

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",

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException
from fastapi.responses import StreamingResponse
from sqlmodel import Field, Session, SQLModel, create_engine

engine = create_engine("postgresql+psycopg://postgres:postgres@localhost/db")


class User(SQLModel, table=True):
    id: int | None = Field(default=None, primary_key=True)
    name: str


app = FastAPI()


def get_session():

    Optional,
    Union,
)
from weakref import WeakKeyDictionary

import fastapi
from fastapi._compat import (
    BaseConfig,
    ModelField,
    PydanticSchemaGenerationError,
    Undefined,
    UndefinedType,
    Validator,
    annotation_is_pydantic_v1,
)
from fastapi.datastructures import DefaultPlaceholder, DefaultType
from fastapi.exceptions import FastAPIDeprecationWarning, PydanticV1NotSupportedError

## Den `fastapi run` Befehl verwenden { #use-the-fastapi-run-command }

Kurz gesagt, nutzen Sie `fastapi run`, um Ihre FastAPI-Anwendung bereitzustellen:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:solid">main.py</u>

  <span style="background-color:#009485"><font color="#D3D7CF"> FastAPI </font></span>  Starting production server 🚀

"""
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(),
):

Das komplexeste Problem besteht darin, einen Authentifizierungs-/Autorisierungsanbieter wie solche aufzubauen, aber **FastAPI** reicht Ihnen die Tools, das einfach zu erledigen, während Ihnen die schwere Arbeit abgenommen wird.

///

## **FastAPI** Tools { #fastapi-utilities }

FastAPI stellt für jedes dieser Sicherheitsschemas im Modul `fastapi.security` verschiedene Tools bereit, die die Verwendung dieser Sicherheitsmechanismen vereinfachen.

The most complex problem is building an authentication/authorization provider like those, but **FastAPI** gives you the tools to do it easily, while doing the heavy lifting for you.

///

## **FastAPI** utilities { #fastapi-utilities }

FastAPI provides several tools for each of these security schemes in the `fastapi.security` module that simplify using these security mechanisms.

Using it in your editor is what really shows you the benefits of FastAPI, seeing how little code you have to write, all the type checks, autocompletion, etc.

---

## Install FastAPI { #install-fastapi }

The first step is to install FastAPI.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then **install FastAPI**:

<div class="termy">

```console

from typing import Annotated

from fastapi import FastAPI, File, UploadFile
from fastapi.responses import HTMLResponse

app = FastAPI()


@app.post("/files/")
async def create_files(
    files: Annotated[list[bytes], File(description="Multiple files as bytes")],
):
    return {"file_sizes": [len(file) for file in files]}


@app.post("/uploadfiles/")
async def create_upload_files(
    files: Annotated[

from typing import Any

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict


def test_read_with_orm_mode() -> None:
    class PersonBase(BaseModel):
        name: str
        lastname: str

    class Person(PersonBase):
        @property
        def full_name(self) -> str:
            return f"{self.name} {self.lastname}"