[Feature request] Possibility to use dependency class name for Body instead of generated name

[AlexanderPodorov]

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Example Code

from dataclasses import dataclass
from typing import Annotated

from fastapi import Depends, FastAPI, File, Form, UploadFile
from pydantic import BaseModel, TypeAdapter

api = FastAPI()


@dataclass
class Test:
    a1: Annotated[str, Form()]
    a2: Annotated[str, Form()]
    a3: Annotated[UploadFile, File()]


TestDep = Annotated[Test, Depends()]


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class ItemOut(BaseModel):
    item_name: str


@api.get("/items")
async def read_items(t: TestDep) -> ItemOut:
    item = TypeAdapter(ItemOut).validate_python(fake_items_db[0])
    return ItemOut.model_validate(item)

Description

When we use non-JSON body parameters, e.g. Form or File, we got the request body schema name generated by FastAPI:

If we use a user-defined class (Test in my example) to wrap all body params into it, can FastAPI use this name? It would be ideal. If it's not possible for any reason, can we have a way to override auto-generated name?
I think it would be reasonable to use class name in case if all params are wrapped by this class, otherwise auto-generate the name.

Operating System

macOS

Operating System Details

No response

FastAPI Version

0.101.0

Pydantic Version

2.1.1

Python Version

Python 3.11.4

Additional Context

No response

[YuriiMotov]

I think this is not possible.

The Body_read_items_items_get that you see in openapi is the schema of whole request body of the endpoint.
Following the way you described, if we use this type in several endpoints, the request body schema should be named the same way (TestDep?).
But what if second endpoint includes other Form parameters along with this dependency? All these parameters should be included into the request body schema.

This is why FastAPI creates different request body schemas for every endpoint and uses the endpoint function name and http-method to construct the name of this schema.

You can modify the way those name are being created using generate_unique_id_function parameter:

counter = {"request_body": 0}

def generate_unique_id(route: APIRoute) -> str:
    counter["request_body"] += 1
    return str(counter["request_body"])

app = FastAPI(generate_unique_id_function=generate_unique_id)

By default this one is used:

fastapi/fastapi/utils.py

Lines 179 to 184 in b2d7420

	def generate_unique_id(route: "APIRoute") -> str:
	operation_id = f"{route.name}{route.path_format}"
	operation_id = re.sub(r"\W", "_", operation_id)
	assert route.methods
	operation_id = f"{operation_id}_{list(route.methods)[0].lower()}"
	return operation_id