This is still supported thanks to **Pydantic**, as it has <a href="https://docs.pydantic.dev/latest/concepts/dataclasses/#use-of-stdlib-dataclasses-with-basemodel" class="external-link" target="_blank">internal support for `dataclasses`</a>.

So, even with the code above that doesn't use Pydantic explicitly, FastAPI is using Pydantic to convert those standard dataclasses to Pydantic's own flavor of dataclasses.

And of course, it supports the same:

* data validation

                    corresponding JSON. But if the data in the object returned is not
                    valid, that would mean a violation of the contract with the client,
                    so it's an error from the API developer. So, FastAPI will raise an
                    error and return a 500 error code (Internal Server Error).

                Read more about it in the

# Precompiling results in some action conflicts. Disable it for now until
# the problematic targets are fixed.
common --@rules_python//python/config_settings:precompile=force_disabled

# TF now has `cc_shared_library` targets, so it needs the experimental flag
# TODO(rostam): Remove when `cc_shared_library` is enabled by default
common --experimental_cc_shared_library

# cc_shared_library ensures no library is linked statically more than once.

        // No point in parsing the source file if the method is not there any more.
        if (method.changeStatus == JApiChangeStatus.REMOVED) {
            return false
        }
        // @Override has source retention - so we need to peek into the sources
        return repository.isOverride(method)
    }

    Violation acceptOrReject(JApiCompatibility member, Violation rejection) {

---

„_Ehrlich, was Du gebaut hast, sieht super solide und poliert aus. In vielerlei Hinsicht ist es so, wie ich **Hug** haben wollte – es ist wirklich inspirierend, jemanden so etwas bauen zu sehen._“

            # (e.g. `TypeAdapter(Annotated[int, Field(alias='b')])`). In some cases, we
            # end up building the type adapter from a model field annotation so we
            # need to ignore the warning:
            if shared.PYDANTIC_VERSION_MINOR_TUPLE >= (2, 12):
                from pydantic.warnings import UnsupportedFieldAttributeWarning

        «««
        ```bash
        # Gruß ausgeben
        echo "Hello, World!"
        ```
        »»»

    Source (English) – The code block is a console example containing HTML tags. No comments, so nothing to change here:

        «««
        ```console
        $ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:solid">main.py</u>

            the output should use the alias names (when provided) or the Python
            attribute names. In an API, if you set an alias, it's probably because you
            want to use it in the result, so you probably want to leave this set to
            `True`.
            """
        ),
    ] = True,
    exclude_unset: Annotated[
        bool,
        Doc(
            """

def _should_embed_body_fields(fields: list[ModelField]) -> bool:
    if not fields:
        return False
    # More than one dependency could have the same field, it would show up as multiple
    # fields but it's the same one, so count them by name
    body_param_names_set = {field.name for field in fields}
    # A top level field has to be a single field, not multiple
    if len(body_param_names_set) > 1:
        return True

### German instructions, when to use and when not to use hyphens in words (written in first person, which is you)