app/routes/route_d.py

from fastapi import APIRouter
from ..models.model_d import NPCalcInput
from ..logic.calc_d   import calculate_all_d

router = APIRouter()

@router.post("/calculate/d")
def calc_d(input: NPCalcInput):
    cathode_name = input.cathode_name
    return calculate_all_d(cathode_name, input.dict())