---

## Установка FastAPI { #install-fastapi }

Первый шаг — установить FastAPI.

Убедитесь, что вы создали [виртуальное окружение](../virtual-environments.md){.internal-link target=_blank}, активировали его, и затем **установите FastAPI**:

<div class="termy">

```console

# Test security scheme at the top level, including OpenAPI
# Ref: https://github.com/fastapi/fastapi/discussions/14263
# Ref: https://github.com/fastapi/fastapi/issues/14271
from fastapi import Depends, FastAPI
from fastapi.security import HTTPBearer
from fastapi.testclient import TestClient
from inline_snapshot import snapshot

app = FastAPI()

bearer_scheme = HTTPBearer()


@app.get("/", dependencies=[Depends(bearer_scheme)])

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


class User(BaseModel):
    username: str
    full_name: str | None = None


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

from typing import Union

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: Union[str, None] = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends()):

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: float = 10.5
    tags: list[str] = []


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},

이로인해, FastAPI 0.99.0 이전 버전은 아직 OpenAPI 3.1.0 보다 낮은 버전을 사용했습니다.

///

### Pydantic과 FastAPI `examples`

`examples`를 Pydantic 모델 속에 추가할 때, `schema_extra` 혹은 `Field(examples=["something"])`를 사용하면 Pydantic 모델의 **JSON 스키마**에 해당 예시가 추가됩니다.

그리고 Pydantic 모델의 **JSON 스키마**는 API의 **OpenAPI**에 포함되고, 그 후 문서 UI 속에서 사용됩니다.

from typing import Annotated, Union

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: Union[str, None] = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@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=[

///

/// note | Detalles Técnicos

También podrías usar `from starlette.responses import JSONResponse`.

**FastAPI** proporciona los mismos `starlette.responses` que `fastapi.responses` solo como una conveniencia para ti, el desarrollador. Pero la mayoría de los responses disponibles provienen directamente de Starlette. Lo mismo con `status`.

///