Default value in dart Map

Question

Is there a way to get a default value from a Map in dart (like Java):

static Map DEFAULT_MAPPING = Map.unmodifiable({
    "k1": "value"
});

DEFAULT_MAPPING['k1'] //get 'value'

DEFAULT_MAPPING.getOrElse('non-present-key', 'default-value') //something like Java has

Answer 1

If your map does not contains null values, you can use if null operator:

var map = {
  'a': 1,
  'b': 2,
};
var cValue = map['c'] ?? 3;

Alternativelly you can define your own extension method:

extension DefaultMap<K,V> on Map<K,V> {
  V getOrElse(K key, V defaultValue) {
    if (this.containsKey(key)) {
      return this[key];
    } else {
      return defaultValue;
    }
  }
}

var map = {
  'a': 1,
  'b': 2,
};
var cValue = map.getOrElse('c', 3);