Discern between default value and provided value for None as a query parameter

[Subaku]

Hello,

I've got a use case that sometimes comes up. When filtering my DB querying for "null" from the client on a particular field is a valid thing to do. This of course translates to None. Problem is most of the time query parameters of optional for me. How might I determine which None I'm dealing with? I.e. did the client explicitly provide the parameter or was it missing and None was set as the default.

From similar issues I'm thinking that maybe some kind of middleware to determine if I actually passed a value or not might be in order but wanted to see if I'm missing something elegant.

Thanks!

[ilyasotkov]

@Subaku Did you find a solution/workaround for this?

My use case:

• x_enable is False by default
• x_value is 0 by default

If the user sets x_value to a value >0, x_enable can be assumed True, unless x_enable is explicitly set to False. So I need a way to know whether x_enable is False because it's the default or because it was supplied by the user.

[ilyasotkov]

I am able to solve this by getting the query param value from the raw request. Example:

from fastapi import FastAPI, Request
from pydantic.validators import BOOL_FALSE

app = FastAPI()


@app.get("/")
def read_root(request: Request, x_enable: bool = False):
    if not x_enable:
        if request.query_params.get("x_enable", "").lower() in BOOL_FALSE:
            # We know that x_enable was set to false by the user
            ...
        else:
            # x_enable is False because it's the default
            ...