#### Data "schema"

The term "schema" might also refer to the shape of some data, like a JSON content.

In that case, it would mean the JSON attributes, and data types they have, etc.

#### OpenAPI and JSON Schema

    # Uvicorn with uvloop
    "uvicorn[standard] >=0.12.0",
    # TODO: this should be part of some pydantic optional extra dependencies
    # # Settings management
    # "pydantic-settings >=2.0.0",
    # # Extra Pydantic data types
    # "pydantic-extra-types >=2.0.0",
]

all = [
    "fastapi-cli >=0.0.2",
    # # For the test client
    "httpx >=0.23.0",
    # For templates
    "jinja2 >=2.11.2",

@app.get("/items/{item_id}")
def get_item(item_id: str, username: Annotated[str, Depends(get_username)]):
    if item_id not in data:
        raise HTTPException(status_code=404, detail="Item not found")
    item = data[item_id]
    if item["owner"] != username:
        raise OwnerError(username)
    return item
```

---

* <a href="https://github.com/Kludex/python-multipart" target="_blank"><code>python-multipart</code></a> - Követelmény ha <abbr title="converting the string that comes from an HTTP request into Python data">"parsing"</abbr>-ot akarsz támogatni, `request.form()`-al.
* <a href="https://pythonhosted.org/itsdangerous/" target="_blank"><code>itsdangerous</code></a> - Követelmény `SessionMiddleware` támogatáshoz.

```Python
my_user: User = User(id=3, name="John Doe", joined="2018-07-19")

second_user_data = {
    "id": 4,
    "name": "Mary",
    "joined": "2018-11-30",
}

my_second_user: User = User(**second_user_data)
```

!!! info
    `**second_user_data` means:

    Pass the keys and values of the `second_user_data` dict directly as key-value arguments, equivalent to: `User(id=4, name="Mary", joined="2018-11-30")`

# OpenAPI Webhooks

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps

In your WebSocket route you can `await` for messages and send messages.

```Python hl_lines="48-52"
{!../../../docs_src/websockets/tutorial001.py!}
```

You can receive and send binary, text, and JSON data.

## Try it

If your file is named `main.py`, run your application with:

<div class="termy">

```console
$ fastapi dev main.py

```

But possibly the most important part of the callback is making sure that your API user (the external developer) implements the *external API* correctly, according to the data that *your API* is going to send in the request body of the callback, etc.

So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> cho phần web.
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> cho phần data.

## Cài đặt

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

```

... àti pẹ̀lú ìkéde kan ṣoṣo yẹn ìwọ yóò gbà:

* Atilẹyin olootu, pẹ̀lú:
    * Pipari.
    * Àyẹ̀wò irúfẹ́ àmì ìtọ́kasí.
* Ìfọwọ́sí àkójọf'áyẹ̀wò (i.e. data):
    * Aṣiṣe alaifọwọyi/aládàáṣiṣẹ́ àti aṣiṣe ti ó hàn kedere nígbàtí àwọn àkójọf'áyẹ̀wò (i.e. data) kò wulo tabi tí kò fẹsẹ̀ múlẹ̀.
    * Ìfọwọ́sí fún ohun elo JSON tí ó jìn gan-an.