* Data validation
* API annotation and automatic documentation

And you only have to declare them once.

Bạn viết chuẩn Python với kiểu dữ liệu như sau:

```Python
from datetime import date

from pydantic import BaseModel

# Declare a variable as a str
# and get editor support inside the function
def main(user_id: str):
    return user_id


# A Pydantic model
class User(BaseModel):
    id: int
    name: str
    joined: date
```

Sau đó có thể được sử dụng:

```Python

* **TCP doesn't know about "domains"**. Only about IP addresses.
    * The information about the **specific domain** requested goes in the **HTTP data**.
* The **HTTPS certificates** "certify" a **certain domain**, but the protocol and encryption happen at the TCP level, **before knowing** which domain is being dealt with.

        comment_id=comment_id,
        body=body,
    )
    response = UpdateCommentResponse.parse_obj(data)
    return response.data.updateDiscussionComment.comment


if __name__ == "__main__":
    settings = Settings()
    if settings.input_debug:
        logging.basicConfig(level=logging.DEBUG)
    else:
        logging.basicConfig(level=logging.INFO)

                    "count": count,
                    "avatarUrl": author.avatarUrl,
                    "url": author.url,
                }
            )
    return users


if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)
    settings = Settings()
    logging.info(f"Using config: {settings.model_dump_json()}")
    g = Github(settings.input_token.get_secret_value())

import pytest
from httpx import AsyncClient

from .main import app


@pytest.mark.anyio
async def test_root():
    async with AsyncClient(app=app, base_url="http://test") as ac:
        response = await ac.get("/")
    assert response.status_code == 200

from fastapi.testclient import TestClient

from .main import app

client = TestClient(app)


def test_read_item():
    response = client.get("/items/foo", headers={"X-Token": "coneofsilence"})
    assert response.status_code == 200
    assert response.json() == {
        "id": "foo",
        "title": "Foo",
        "description": "There goes my hero",
    }


def test_read_item_bad_token():

Sebastián Ramírez <******@****.***> 1698179166 +0400

# Security - First Steps

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

* `main`: el archivo `main.py` (el"modulo" de Python).
* `app`: el objeto creado dentro de `main.py` con la línea `app = FastAPI()`.
* `--reload`: hace que el servidor se reinicie después de cambios en el código. Esta opción solo debe ser usada en desarrollo.

</details>

### Revísalo