Shows how to refactor Python code using the early exit pattern

early_exit.py

# Code for blog article:
# https://www.helmut.dev/early-exit.html

# Original code
if post_data:
    thing = post_data.get("thing")
    if thing is not None:
        setting = get_user_setting(user, thing)
        if setting is not None:
            permission = get_user_permission(user)
            if permission is True:
                if user.is_superuser:
                    return DataPoint.objects.all()
                elif user.is_staff:
                    return DataPoint.objects.filter(user=user)
                else:
                    return DataPoint.objects.filter(user=user, thing=thing)
            else:
                return "Permission denied"
        else:
            return "Setting not found"
    else:
        return "Thing not specified"
else:
    return "No data posted"

# Refactored code
if not post_data:
    return "No data posted"

thing = post_data.get("thing")
if thing is None:
    return "Thing not specified"

setting = get_user_settig(user, thing)
if setting is None:
    return "Setting not found"

permission = get_user_permission(user)
if permission is False:
    return "Permission denied"

if user.is_superuser:
    return DataPoint.objects.all()

if user.is_staff:
    return DataPoint.objects.filter(user=user)

return DataPoint.objects.filter(user=user, thing=thing)