how to filter null values from map in Dart

Question

Following the map, having both key-value pair as dynamic, Write a logic to filter all the null values from Map without us?

Is there any other approach than traversin

Answer 1

Use removeWhere on Map to remove entries you want to filter out:

void main() {
  final map = {'text': null, 'body': 5, null: 'crap', 'number': 'ten'};

  map.removeWhere((key, value) => key == null || value == null);

  print(map); // {body: 5, number: ten}
}

And if you want to do it as part of your toMap() method you can do something like this with the cascade operator:

void main() {
  print(A(null, 'Jensen').toMap()); // {lastName: Jensen}
}

class A {
  final String firstName;
  final String lastName;

  A(this.firstName, this.lastName);

  Map toMap() {
    return {
      'firstName': this.firstName,
      'lastName': this.lastName
    }..removeWhere(
        (dynamic key, dynamic value) => key == null || value == null);
  }
}