Let's say a request is submitted to the /Test route of your FastAPI application with the following parameters.

http://api.example.com/?foo=Hello&bar=World

Request can be used to get the values (Hello and World) from the keys (foo and bar). 

from fastapi import FastAPI, Request

app = FastAPI()

@app.get("/")
async def root(request: Reqest):
    return {"foo": request.query_params['foo'], "bar": request.query_params['bar']}