c# Coalesce operator crashes on null

Question

pulling data from database I have this this

Result = main.Verified.Equals("1", StringComparison.OrdinalIgnoreCase) ? "Good Sale" : "Bad Sale";

Problem is that main.Verified is sometimes null and so it crashes with object reference error

What is an easy way to fix?

I was looking at this, but I'm not sure it has the best solution ?? Coalesce for empty string?

if main.Verified is null do you consider it as "Good Sale" or "Bad Sale"? — Shai Aharoni, Feb 22 '17 at 22:34
Technically, you are using a ternary. *not* a null coalescing operator — BradleyDotNET, Feb 22 '17 at 22:34
@ShaiAharoni - null should not happen , it is bad data so think think Bad sale — , Feb 22 '17 at 22:45
@JeremyMiller "Shouldn't happen" as in "there's an unfixed bug somewhere" or "shouldn't happen" as in "something unexpected happened"? If it's the first, then you **want** it to crash here (rather than just ignore the issue) and the solution is to fix the bug. If it's a "bad sale," is there some kind of sensible action that your program can do to fix the issue? — EJoshuaS - Stand with Ukraine, Feb 22 '17 at 22:55

Silas Reinagel · Accepted Answer · 2017-02-22T22:38:19.283

4

Put the const value string first in the comparison.

Result = "1".Equals(main.Verified, StringComparison.OrdinalIgnoreCase) 
    ? "Good Sale" 
    : "Bad Sale";

This works because string.Equals() will always return false when compared with null. However, calling .Equals() on a null reference will always throw a NullReferenceException.

edited Feb 22 '17 at 22:38

answered Feb 22 '17 at 22:34

Silas Reinagel

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ok, but I will never pull in "1" , so what can i do to first check for null? – Feb 22 '17 at 22:46
2

You could write a more complex condition. `Result = (main != null && main.Verified != null && main.Verfified.Equals("1", StringComparison.OrdinalIgnoreCase)) ? "Good Sale" : "Bad Sale";` – Silas Reinagel Feb 22 '17 at 22:50

score 0 · Answer 2 · answered Feb 23 '17 at 00:17

0

You could always do this:

Result =
    (main.Verified ?? "")
        .Equals("1", StringComparison.OrdinalIgnoreCase)
        ? "Good Sale"
        : "Bad Sale";

answered Feb 23 '17 at 00:17

Enigmativity

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thanks I am also now hearing that per a business rule if it is null that i need to log it , so essentially if it is "1" is good, 2 -9 bad sale , and null is neither it gets some log to db or email or file ... – Feb 23 '17 at 05:05

c# Coalesce operator crashes on null

2 Answers2