It just returns a JSON response with the result of the application's `.openapi()` method.

By default, what the method `.openapi()` does is check the property `.openapi_schema` to see if it has contents and return them.

If it doesn't, it generates them using the utility function at `fastapi.openapi.utils.get_openapi`.

And that function `get_openapi()` receives as parameters:

* `title`: The OpenAPI title, shown in the docs.

The `TestClient` does some magic inside to call the asynchronous FastAPI application in your normal `def` test functions, using standard pytest. But that magic doesn't work anymore when we're using it inside asynchronous functions. By running our tests asynchronously, we can no longer use the `TestClient` inside our test functions.

That means that if you want to update the item `bar` using `PUT` with a body containing:

```Python
{
    "name": "Barz",
    "price": 3,
    "description": None,
}
```

because it doesn't include the already stored attribute `"tax": 20.2`, the input model would take the default value of `"tax": 10.5`.

And the data would be saved with that "new" `tax` of `10.5`.

## Partial updates with `PATCH`

    But by declaring the type as `Session`, the editor now can know the available methods (`.add()`, `.query()`, `.commit()`, etc) and can provide better support (like completion). The type declaration doesn't affect the actual object.

### Create your **FastAPI** *path operations*

        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="68-69  81"
    {!> ../../../docs_src/websockets/tutorial002.py!}
    ```

!!! info
    As this is a WebSocket it doesn't really make sense to raise an `HTTPException`, instead we raise a `WebSocketException`.

    if is_mkdocs_insiders():
        print("Using insiders")
    lang_path: Path = Path("docs") / lang
    if not lang_path.is_dir():
        typer.echo(f"The language translation doesn't seem to exist yet: {lang}")
        raise typer.Abort()
    typer.echo(f"Building docs for: {lang}")
    build_site_dist_path = build_site_path / lang
    if lang == "en":
        dist_path = site_path

```Python hl_lines="2"
@app.get('/')
def results():
    results = some_library()
    return results
```

---

## OpenAPI and API docs

If you return additional status codes and responses directly, they won't be included in the OpenAPI schema (the API docs), because FastAPI doesn't have a way to know beforehand what you are going to return.

    ```

This specific regular expression pattern checks that the received parameter value:

* `^`: starts with the following characters, doesn't have characters before.
* `fixedquery`: has the exact value `fixedquery`.
* `$`: ends there, doesn't have any more characters after `fixedquery`.

# HTTP Basic Auth

For the simplest cases, you can use HTTP Basic Auth.

In HTTP Basic Auth, the application expects a header that contains a username and a password.

If it doesn't receive it, it returns an HTTP 401 "Unauthorized" error.

And returns a header `WWW-Authenticate` with a value of `Basic`, and an optional `realm` parameter.

That tells the browser to show the integrated prompt for a username and password.