How to handle a bool if it doesn't exist?

Question

I have created a simplified scenario below of my problem. I need to set EmptyBookingAllowed to true or false, however AllowEmptyBooking will not exist in the config for certain customers.

How do I set EmptyBookingAllowed to true if the config.AllowEmptyBooking otherwise set it to the value of config.AllowEmptyBooking.

public Class BookingSession()
{
    public string Username {get; set;}
    public bool EmptyBookingAllowed {get; set;}
}

BookingSession session = new BookingSession(){ 
    Username            = "whatever",  
    EmptyBookingAllowed = config.AllowEmptyBookings
};

Does config.AllowEmptyBookings allow for the concept of "not defined", or will it then have a default value of "false"? — Hans Keﬆing, Mar 02 '22 at 10:56
If the `config` is `null` when it does not exists... Then like this `EmptyBookingAllowed = config?.AllowEmptyBookings ?? true` — Dusan, Mar 02 '22 at 10:56
How is your config class and how is your config class mapped? Making config.AllowEmptyBookings nullable like `bool?` and doing a null check while settings EmptyBookingAllowed may help — YD9, Mar 02 '22 at 10:57
verify if property exists https://stackoverflow.com/a/15341181/5605739 — Celso Lívero, Mar 02 '22 at 10:58
you need `EmptyBookingAllowed ` to be a nullable type `bool?`. — MakePeaceGreatAgain, Mar 02 '22 at 11:07
What is the type of `config`? And what is the type of `config.AllowEmptyBookings`? — derpirscher, Mar 02 '22 at 11:10

Troy Turley · Answer 1 · 2022-03-02T11:02:47.477

0

Use the Null-coalescing operator:

EmptyBookingAllowed = (config?.AllowEmptyBookings ?? true);

edited Mar 02 '22 at 11:02

answered Mar 02 '22 at 10:57

Troy Turley

659
10
28

it's not work for empty config. Better use `(config?.AllowEmptyBookings ?? true)` – Lofem Mar 02 '22 at 10:59
It should be `config?.AllowEmptyBookings ?? true` (`?.` instead of `?`): note, that if `AllowEmptyBookings` is `bool` it always exists, while `config` can be `null` – Dmitry Bychenko Mar 02 '22 at 11:00
Just to clarify, config will always exists, however config.AllowEmptyBookings may not always exist. – joehelsing Mar 02 '22 at 11:02
@joehelsing Then you need to use `bool?` instead of `bool` for the `AllowEmptyBookings` in your config class. – Dusan Mar 02 '22 at 11:06
@joehelsing if it is a `bool` and not a `bool?` (nullable), then it _always_ exists. – Franz Gleichmann Mar 02 '22 at 11:06
But I think it is better to intercept non-existent config case in the code that actually loads the config... In there, if config does not exists, you can populate it with the defaults (instead of making fields nullable)... That will make your code that actually uses config simpler. – Dusan Mar 02 '22 at 11:10

How to handle a bool if it doesn't exist?

1 Answers1