), "overridden configs should be preserved"
    assert (
        '"deepLinking": true' not in response.text
    ), "overridden configs should not include the old value"
    assert (
        '"syntaxHighlight": false' not in response.text
    ), "not used parameters should not be included"
    assert (
        '"dom_id": "#swagger-ui"' in response.text
    ), "default configs should be preserved"

                ],
            ),
        ):
            return item

    # TODO: enable these tests once/if Form(embed=False) is supported
    # TODO: In that case, define if File() should support example/examples too
    # @app.post("/form_example")
    # def form_example(firstname: str = Form(example="John")):
    #     return firstname

    # @app.post("/form_examples")
    # def form_examples(

### Breaking Changes

* PR [#2434](https://github.com/tiangolo/fastapi/pull/2434) includes several improvements that shouldn't affect normal use cases, but could affect in advanced scenarios:
    * If you are testing the generated OpenAPI (you shouldn't, FastAPI already tests it extensively for you): the order for `tags` in `include_router` and *path operations* was updated for consistency, but it's a simple order change.

</blockquote>

## Investigation

By using all the previous alternatives I had the chance to learn from all of them, take ideas, and combine them in the best way I could find for myself and the teams of developers I have worked with.

For example, it was clear that ideally it should be based on standard Python type hints.

Also, the best approach was to use already existing standards.

                    "loc": ["query", "skip"],
                    "msg": "Input should be a valid integer, unable to parse string as an integer",
                    "input": "a",
                },
                {
                    "type": "int_parsing",
                    "loc": ["query", "limit"],
                    "msg": "Input should be a valid integer, unable to parse string as an integer",
                    "input": "b",

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial008b.py!}
    ```

In both cases this means that `item` could be an `int` or a `str`.

#### Possibly `None`

You can declare that a value could have a type, like `str`, but that it could also be `None`.

In Python 3.6 and above (including Python 3.10) you can declare it by importing and using `Optional` from the `typing` module.

# Conditional OpenAPI

If you needed to, you could use settings and environment variables to configure OpenAPI conditionally depending on the environment, and even disable it entirely.

## About security, APIs, and docs

Hiding your documentation user interfaces in production *shouldn't* be the way to protect your API.

That doesn't add any extra security to your API, the *path operations* will still be available where they are.

        {
            "detail": {
                "errors": [
                    {
                        "type": "list_type",
                        "loc": ["body"],
                        "msg": "Input should be a valid list",
                        "input": {"numbers": [1, 2, 3]},
                    }
                ],
                "body": '{"numbers": [1, 2, 3]}',
            }
        }
    ) | IsDict(

It would also mean that if you get data from the `Request` object directly (for example, read the body) it won't be validated, converted or documented (with OpenAPI, for the automatic API user interface) by FastAPI.

Although any other parameter declared normally (for example, the body with a Pydantic model) would still be validated, converted, annotated, etc.

### Import `APIRouter`

You import it and create an "instance" the same way you would with the class `FastAPI`:

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

### *Path operations* with `APIRouter`

And then you use it to declare your *path operations*.

Use it the same way you would use the `FastAPI` class: