I'm getting a null safety error on Future forEach

September 26, 2023

I’m getting The operator ‘[]’ isn’t defined for the type ‘Object’ on my element![‘id’].

Code:

await Future.forEach(tempList, (element) async {
          if (element!['id'] == alertId) {
            alertList!.add(element);
            screenTitle = element!['subject'] ;
          
          }
        });

How to fix this?
Thanks.

>Solution :

You need to check the type of element before accessing it with []. It seems that it’s not a map like it is supposed to be.

Moreover it’s seems like you’re using null check operator ("!") on a value that can be null. It is a good pratice to ensure that your value is not null before acessing it.

To correct that you can do it like this.

await Future.forEach(tempList, (element) async {
          if(element != null && element is Map<String,dynamic>){
            if (element!['id'] == alertId) {
              alertList!.add(element);
              screenTitle = element!['subject'] ;
            }  
          }
        });

I advise you to type your variables to be aware of what type you’re using for each variable and avoid this kind of error.