app = FastAPI()
app.state.value = 42


async def extract_value_from_http_connection(conn: HTTPConnection):
    return conn.app.state.value


@app.get("/http")
async def get_value_by_http(value: int = Depends(extract_value_from_http_connection)):
    return value


@app.websocket("/ws")
async def get_value_by_ws(
    websocket: WebSocket, value: int = Depends(extract_value_from_http_connection)
):
    await websocket.accept()

You can extend the OpenAPI schema for a *path operation* using the parameter `openapi_extra`.

### OpenAPI Extensions

This `openapi_extra` can be helpful, for example, to declare [OpenAPI Extensions](https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#specificationExtensions):

```Python hl_lines="6"

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

**FastAPI** will use that *temporal* response to extract the status code (also cookies and headers), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

**FastAPI** will use that *temporal* response to extract the headers (also cookies and status code), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

**FastAPI** will use that *temporal* response to extract the cookies (also headers and status code), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

## 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.

So, by default, `Header` will convert the parameter names characters from underscore (`_`) to hyphen (`-`) to extract and document the headers.

## Adicione informações extras

Você pode declarar informação extra em `Field`, `Query`, `Body`, etc. E isso será incluído no JSON Schema gerado.

Você irá aprender mais sobre adicionar informações extras posteriormente nessa documentação, quando estiver aprendendo a declarar exemplos.

## Recapitulando

Você pode usar `Field` do Pydantic para declarar validações extras e metadados para atributos do modelo.

Sebastián Ramírez <******@****.***> 1688149516 +0200

    Aber **FastAPI** wird wissen, dass es zuerst `query_extractor` auflösen muss, um dessen Resultat `query_or_cookie_extractor` zu übergeben, wenn dieses aufgerufen wird.

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query

## Add extra information

You can declare extra information in `Field`, `Query`, `Body`, etc. And it will be included in the generated JSON Schema.

You will learn more about adding extra information later in the docs, when learning to declare examples.

!!! warning