How to actually check for null to comply with Sound null-safety in Dart

Question

What is the recommended way to check for null with the new "sound null-safety" feature of Dart , specially for the compiler to stop complaining, this doesn't work:

I'm obviously checking that value.data isn't null before accessing it.

@Dude That might assign `null` to `profile.profilePic` which might not be allowed or desired, while the code in the screen shot ignores the case where `value.data == null` — spkersten, Jan 08 '21 at 13:39

score 2 · Accepted Answer · answered Jan 08 '21 at 11:30

2

Only local variables will get promoted.

so if you say

final temp = value.data;

if(temp != null) {
   profile.profilePic = temp.url;
}

it should work.

answered Jan 08 '21 at 11:30

nvoigt

75,013
26
93
142

yikes, this sound null-safety thing is cool but this is a lot of code added if we want to play by the rules. – Daniel Arechiga Jan 08 '21 at 16:59
In general it’s not that bad. I think this is the worse case. – spkersten Jan 08 '21 at 17:19

score -1 · Answer 2 · answered Jan 08 '21 at 05:55

-1

define

yourVariable? aNullableInt = null;

answered Jan 08 '21 at 05:55

Jayesh Shinde

71
7

can you be more specific? – Daniel Arechiga Jan 08 '21 at 06:47

How to actually check for null to comply with Sound null-safety in Dart

2 Answers2