I have downloaded fastapi , but got an error of no module found
so I installed in virtual environment , where I used

 pip install fastapi[all]

main.py

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def root():
    return {"message": "Hello World"}

Now I am trying to run this I get

(venv) C:UsersDELLDesktopAPI>uvicorn main:app
ERROR:    Error loading ASGI app. Attribute "app" not found in module "main".

I even tried

 uvicorn main:app --reload 

but still not worked Where am I going wrong I am sure that I am using virtual environment , and virtual environment python interpretor too

Need to solve this, I am expecting
{message: Hello World}