Dart nested Map getter/setter

Get and Set your nested Map without converting them to a model mapped version. Just use the key path to go directly where you want and get, set keys and values.

Nested Map Getter

Get value from a Map by path. Use dot notation in [path] to access nessted keys. If location of path doesn't exist, it will return defaultValue.

T? mapGetter<T>(Map map, String path, T defaultValue) {
  List<String> keys = path.split('.');
  String key = keys[0];

  if (!map.containsKey(key)) {
    return defaultValue;
  }

  if (keys.length == 1) {
    return map[key] as T;
  }

  return mapGetter(map[keys.removeAt(0)], keys.join('.'), defaultValue);
}

Example:

 Map<String, dynamic> a = {
    'a': {
      'b': {
        'c': {
          'd': 'This is d',
        },
      }
    }
  };

  Map<String, dynamic>? c = mapGetter<Map<String, dynamic>>(a, 'a.b.c', {});
  String? d = mapGetter(a, 'a.b.c.d', 'no value');
  String? e = mapGetter(a, 'a.b.c.e', 'no value');
  print(c);
  print(d);
  print(e);

Output:

{d: This is d}
This is d
no value

Nested Map Setter

Sets value to the Map by path. If location of path doesn't exist, it will created.

Map<String, dynamic> mapSetter<T>(
  Map<String, dynamic>? map,
  String path,
  T value,
) {
  List<String> keys = path.split('.');
  String key = keys[0];
  Map<String, dynamic> target = map ?? {};

  if (keys.length == 1) {
    return Map<String, dynamic>.from({
      ...target,
      key: value,
    });
  }

  return Map<String, dynamic>.from({
    ...target,
    key: mapSetter(target[keys.removeAt(0)] ?? {}, keys.join('.'), value),
  });
}

Example:

  Map<String, dynamic> a = {
    'a': {
      'b': {
        'c': {
          'd': 'This is d',
        },
      }
    }
  };

  Map<String, dynamic> d = mapSetter(a, 'a.b.c.d', 'This is d modified');
  Map<String, dynamic> e = mapSetter(d, 'a.b.c.e', 'This is e');
  print(d);
  print(e);

Output:

{a: {b: {c: {d: This is d modified}}}}
{a: {b: {c: {d: This is d modified, e: This is e}}}}