And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

/// info

Keep in mind that dataclasses can't do everything Pydantic models can do.

# GraphQL { #graphql }

As **FastAPI** is based on the **ASGI** standard, it's very easy to integrate any **GraphQL** library also compatible with ASGI.

You can combine normal FastAPI *path operations* with GraphQL on the same application.

/// tip

**GraphQL** solves some very specific use cases.

It has **advantages** and **disadvantages** when compared to common **web APIs**.

                should have all the fields, including the ones that have the same value
                as the default. This is different from `response_model_exclude_unset`
                in that if the fields are set but contain the same default values,
                they will be excluded from the response.

}


def get_openapi_security_definitions(
    flat_dependant: Dependant,
) -> tuple[dict[str, Any], list[dict[str, Any]]]:
    security_definitions = {}
    # Use a dict to merge scopes for same security scheme
    operation_security_dict: dict[str, list[str]] = {}
    for security_dependency in flat_dependant._security_dependencies:
        security_definition = jsonable_encoder(

                    },
                }
            },
            "/response_model-no_annotation-return_same_model": {
                "get": {
                    "summary": "Response Model No Annotation Return Same Model",
                    "operationId": "response_model_no_annotation_return_same_model_response_model_no_annotation_return_same_model_get",
                    "responses": {
                        "200": {

        ```
        »»»


### Special blocks

There are special blocks of notes, tips and others that look like:

    «««
    /// note
    »»»

To translate it, keep the same line and add the translation after a vertical bar.

For example, if you were translating to Spanish, you would write:

    «««
    /// note | Nota
    »»»

Some examples in Spanish:

    Source:

///

{* ../../docs_src/separate_openapi_schemas/tutorial002_py310.py hl[10] *}

### Gleiches Schema für Eingabe- und Ausgabemodelle in der Dokumentation { #same-schema-for-input-and-output-models-in-docs }

Und jetzt wird es ein einziges Schema für die Eingabe und Ausgabe des Modells geben, nur `Item`, und es wird `description` als **nicht erforderlich** kennzeichnen:

///

### Pydantic v1 und v2 in derselben App { #pydantic-v1-and-v2-on-the-same-app }

Es wird von Pydantic **nicht unterstützt**, dass ein Pydantic‑v2‑Modell Felder hat, die als Pydantic‑v1‑Modelle definiert sind, und umgekehrt.

```mermaid
graph TB
    subgraph "❌ Nicht unterstützt"

    return True


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:

        bool,
        Doc(
            """
            Pydantic's `exclude_defaults` parameter, passed to Pydantic models to define
            if it should exclude from the output the fields that had the same default
            value, even when they were explicitly set.
            """
        ),
    ] = False,
    exclude_none: Annotated[
        bool,
        Doc(
            """