Null-aware operator with Maps
Multi tool use
Null-aware operator with Maps
I had the same problem with lists, now it is Map.
Map
The following syntax is not Dart, as in it does not compile:
map?[key] ?? otherValue
If my map was not a Map but a List, it would look like Günter pointed out here:
map
Map
List
list?.elementAt(index) ?? otherValue
I understand that map?[key] is not valid syntax and therefore I am searching for something like elementAt, which works for lists, for maps.
map?[key]
elementAt
map?.valueFor(key) ?? otherValue
That does obviously not yet exist. The problem has solutions and valueOf might be a good one as well.
valueOf
1 Answer
1
This works:
(map ?? const {})[key] ?? otherValue;
Because the key will access an emtpy Map, which will always return null.
key
Map
null
You mean an issue for
map?[key]. I think it's highly unlikely to be added. ? is only supported with .. Supporting it for list?[index] was requested but declined as far as I remember.– Günter Zöchbauer
Jul 2 at 18:00
map?[key]
?
.
list?[index]
For something like
map.valueOf(key).– creativecreatorormaybenot
Jul 2 at 18:04
map.valueOf(key)
I see. Might be worth a try.
– Günter Zöchbauer
Jul 2 at 18:11
Consider using
const {} to avoid creating a new map every time, at least when the types allow it.– lrn
Jul 3 at 10:00
const {}
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That does work and looks nice. I wonder how it did not come to my mind and if I should create an issue for that.
– creativecreatorormaybenot
Jul 2 at 17:42