]
}
foo_is_short = {
    "detail": [
        IsDict(
            {
                "ctx": {"min_length": 1},
                "loc": ["query", "foo"],
                "msg": "String should have at least 1 character",
                "type": "string_too_short",
                "input": "",
            }
        )
        # TODO: remove when deprecating Pydantic v1
        | IsDict(
            {

## Automatic conversion

`Header` has a little extra functionality on top of what `Path`, `Query` and `Cookie` provide.

Most of the standard headers are separated by a "hyphen" character, also known as the "minus symbol" (`-`).

But a variable like `user-agent` is invalid in Python.

```

## Advanced description from docstring

You can limit the lines used from the docstring of a *path operation function* for OpenAPI.

Adding an `\f` (an escaped "form feed" character) causes **FastAPI** to truncate the output used for OpenAPI at this point.

It won't show up in the documentation, but other tools (such as Sphinx) will be able to use the rest.

```Python hl_lines="19-29"

            self.secure_cloned_response_field = None
        self.dependencies = list(dependencies or [])
        self.description = description or inspect.cleandoc(self.endpoint.__doc__ or "")
        # if a "form feed" character (page break) is found in the description text,
        # truncate description text to the content preceding the first "form feed"
        self.description = self.description.split("\f")[0].strip()
        response_fields = {}