[QUESTION] Use UploadFile in Pydantic model

Description

Is it possible to use UploadFile in a Pydantic model? The FastAPI docs say “FastAPI’s UploadFile inherits directly from Starlette’s UploadFile, but adds some necessary parts to make it compatible with Pydantic and the other parts of FastAPI.”

from fastapi import FastAPI, File, UploadFile
from pydantic import BaseModel

class PydanticFile(BaseModel):
    file: UploadFile = File(...)

app = FastAPI()

@app.post("/uploadfile/")
async def create_upload_file(file: PydanticFile):
    return {"filename": file.filename}

However, UploadFile does not seem to be compatible with Pydantic. The code above – derived from the example in FastAPI’s Request Files tutorial – raises a value error:

ValueError: Value not declarable with JSON Schema, field: file type=UploadFile required

[divyeshwendorse]

Thanks a lot for your helpful comment. So I guess I’d have to explicitly separate the file from the JSON part of the multipart form body, as in:

class Properties(BaseModel):
    language: str = None
    author: str = None

@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile = File(...),
                             properties: Properties):
    return {"filename": file.filename}

This seems to be working, and maybe query parameters would ultimately make more sense here.

Hello, This is giving an validation Error (422)

[perezzini]

Thanks for replying back @tiangolo

And congrats on your great job in FastAPI!