How to pass both file (uploaded) and dict params to POST request in FAST API?

Specifically, I want the example below to work:

from fastapi import FastAPI
from fastapi import UploadFile

app = FastAPI()

@app.post("/check")
def foo(grid: dict, file: UploadFile):
    return {"len_grid": len(grid), "filename": file.filename}

Currently, while trying to create a POST request passing any valid dict to grid parameter and upload some file, FAST API raises the error:

  "detail": [
    {
      "loc": [
        "body",
        "grid"
      ],
      "msg": "value is not a valid dict",
      "type": "type_error.dict"
    }
  ]
}

At the same time, if I use only one of these parameters inside the function, it works well.

I am calling (testing) my API this way:

import requests

url = 'http://127.0.0.1:8000/check'
file = {'file': open('ny_pollution_events.csv', 'rb')}
payload = {"grid": {"name": "Alex", "age": 15}}
resp = requests.post(url=url, data=payload, files=file)
print(resp.json())

as well as via in-built Swagger UI.