check list if it is empty or null flutter

Question

I get this from the server, and I need to put my checkbox to true for values ​​with null, while I don't have to do anything if I find []

{"FRI": [null], "MON": [null], "SAT": [null], "SUN": [{"to": "16:27", "from": "15:27"}], "THU": [null], "TUE": [null], "WED": []}

I'm trying with a

if (widget.initialValues!.every((e) => e == null)) {
  _isClosed.trigger(true);
}

but it does not work correctly because in both cases it returns to be true

Solution

when you try to use each item of an array and compare it to null, [null] and [] would have similar results. Instead, you should use .isEmpty because this method defines that is an array is empty or not, and in this approach [null] and []` are not equal because the first one has one element but the other one has 0 elements! For example:

//an example list
const list = [ [], [null]];
  
  for(int i=0; i<list.length; i++){
    if(list[i].isEmpty){
      print("empty " + i.toString());
    } else {
      print("not empty " + i.toString());
    }
  }

and the result will be:

empty 0
not empty 1

Similarly, you can use .length as follow:

const list = [ [], [null]];
for(int i=0; i<list.length; i++){
    print(i.toString() + " length is " + list[i].length.toString());
  }

These are only examples and you can map them to your code as well.

Comments

[Admin]

mm ok, the examples are pretty clear to me, but in my code if I do an if (widget.initialValues! .isEmpty) it also takes me the values ​​with the null ..

[Abbasihsn]

no, you should check element-wise not for entire initial values! because you want to be able to return true for each item that has [null] but in contrast do not want to have this feature for items with []. so you should check whole item separately

[Admin]

mm ok i understand thanks, but I try to write your code but I have error.. I update my question with photo

[Abbasihsn]

I think you are missing something, please provide the initialValue so I can check it out.