):

        @app.get("/items/{item_id}/")
        async def get_item(item_id: Annotated[int, Path(default=1)]):
            pass  # pragma: nocover

    with pytest.raises(
        AssertionError,
        match=(
            "`Query` default value cannot be set in `Annotated` for 'item_id'. Set the"
            " default value with `=` instead."
        ),
    ):

            field_info = params.File(annotation=use_annotation, default=default_value)
        elif not field_annotation_is_scalar(annotation=type_annotation):
            field_info = params.Body(annotation=use_annotation, default=default_value)
        else:
            field_info = params.Query(annotation=use_annotation, default=default_value)

    field = None
    if field_info is not None:

    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/default": {
                "get": {
                    "summary": "Default",
                    "operationId": "default_default_get",
                    "parameters": [
                        {
                            "required": False,
                            "schema": {

# OpenAPI `docs`

Utilities to handle OpenAPI automatic UI documentation, including Swagger UI (by default at `/docs`) and ReDoc (by default at `/redoc`).

::: fastapi.openapi.docs.get_swagger_ui_html

::: fastapi.openapi.docs.get_redoc_html

::: fastapi.openapi.docs.get_swagger_ui_oauth2_redirect_html

```

That configuration would change the syntax highlighting color theme:

<img src="/img/tutorial/extending-openapi/image04.png">

## Change Default Swagger UI Parameters

FastAPI includes some default configuration parameters appropriate for most of the use cases.

It includes these default configurations:

```Python
{!../../../fastapi/openapi/docs.py[ln:7-23]!}
```

    if query is None:
        return "foo bar"
    return f"foo bar {query}"


@app.get("/query/int/default")
def get_query_type_int_default(query: int = 10):
    return f"foo bar {query}"


@app.get("/query/param")
def get_query_param(query=Query(default=None)):
    if query is None:
        return "foo bar"
    return f"foo bar {query}"


@app.get("/query/param-required")

Python will complain if you put a value with a "default" before a value that doesn't have a "default".

But you can re-order them, and have the value without a default (the query parameter `q`) first.

It doesn't matter for **FastAPI**. It will detect the parameters by their names, types and default declarations (`Query`, `Path`, etc), it doesn't care about the order.

    ```

...then because `description` has a default value, if you **don't return anything** for that field, it will still have that **default value**.

### Model for Output Response Data

If you interact with the docs and check the response, even though the code didn't add anything in one of the `description` fields, the JSON response contains the default value (`null`):

<div class="screenshot">

## Override the default exception handlers

**FastAPI** has some default exception handlers.

These handlers are in charge of returning the default JSON responses when you `raise` an `HTTPException` and when the request has invalid data.

You can override these exception handlers with your own.

):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(
    query_or_default: Annotated[str, Depends(query_or_cookie_extractor)],
):