Successfully installed fastapi pydantic uvicorn
```

</div>

/// info

还有其他文件格式和工具来定义和安装依赖项。

 我将在下面的部分中向你展示一个使用 Poetry 的示例。 👇

///

### 创建 **FastAPI** 代码

* 创建`app`目录并进入。
* 创建一个空文件`__init__.py`。
* 创建一个 `main.py` 文件：



```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():

from typing import Annotated

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(

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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


@app.put("/items/{item_id}")

from typing import Union

from fastapi import FastAPI
from pydantic.v1 import BaseModel

app = FastAPI()


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

    class Config:
        schema_extra = {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",

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=[
                {

# 하위 응용프로그램 - 마운트

만약 각각의 독립적인 OpenAPI와 문서 UI를 갖는 두 개의 독립적인 FastAPI 응용프로그램이 필요하다면, 메인 어플리케이션에 하나 (또는 그 이상의) 하위-응용프로그램(들)을 “마운트"해서 사용할 수 있습니다.

## **FastAPI** 응용프로그램 마운트

“마운트"이란 완전히 “독립적인" 응용프로그램을 특정 경로에 추가하여 해당 하위 응용프로그램에서 선언된 *경로 동작*을 통해 해당 경로 아래에 있는 모든 작업들을 처리할 수 있도록 하는 것을 의미합니다.

### 최상단 응용프로그램

먼저, 메인, 최상단의 **FastAPI** 응용프로그램과 이것의 *경로 동작*을 생성합니다:

{* ../../docs_src/sub_applications/tutorial001.py hl[3, 6:8] *}

### 하위 응용프로그램

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

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: float | None = None


@app.put("/items/{item_id}")

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key

from typing import Any, 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.post("/items/", response_model=Item)
async def create_item(item: Item) -> Any:
    return item


@app.get("/items/", response_model=list[Item])

---

## 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