Because of that, versions of FastAPI previous to 0.99.0 still used versions of OpenAPI lower than 3.1.0.

///

### Pydantic and FastAPI `examples` { #pydantic-and-fastapi-examples }

///

## 多个工作进程

您可以使用 `--workers` 命令行选项来启动多个工作进程：

//// tab | `fastapi`

如果您使用 `fastapi` 命令：

<div class="termy">

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

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

from typing import Optional

import pytest
from fastapi import Depends, FastAPI, Security
from fastapi.security import OAuth2, OAuth2PasswordRequestFormStrict
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }

from fastapi import Depends, FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select


class Hero(SQLModel, table=True):
    id: int | None = Field(default=None, primary_key=True)
    name: str = Field(index=True)
    age: int | None = Field(default=None, index=True)
    secret_name: str


sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"

You can import it directly from `fastapi`:

```python
from fastapi import Request
```

/// tip

When you want to define dependencies that should be compatible with both HTTP and WebSockets, you can define a parameter that takes an `HTTPConnection` instead of a `Request` or a `WebSocket`.

///

from typing import Annotated

from fastapi import FastAPI, Path
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: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: str | None = None,
    item: Item | None = None,

from typing import Annotated

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: str | None = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")

from typing import Annotated, Union

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": {

* Якщо параметр оголошується як тип **Pydantic моделі**, він інтерпретується як **тіло** запиту.

/// note

FastAPI буде знати, що значення "q" не є обов'язковим через значення за замовчуванням "= None".

`Optional` у `Optional[str]` не використовується FastAPI, але дозволить вашому редактору надати вам кращу підтримку та виявляти помилки.

///

## Без Pydantic

///

## 使用你的调试器运行代码

由于是从代码直接运行的 Uvicorn 服务器，所以你可以从调试器直接调用 Python 程序（你的 FastAPI 应用）。

---

例如，你可以在 Visual Studio Code 中：

* 进入到「调试」面板。
* 「添加配置...」。
* 选中「Python」
* 运行「Python：当前文件（集成终端）」选项的调试器。

然后它会使用你的 **FastAPI** 代码开启服务器，停在断点处，等等。

看起来可能是这样：

<img src="/img/tutorial/debugging/image01.png">

---

如果使用 Pycharm，你可以：

* 打开「运行」菜单。