safemap 2.0.0-nullsafety.0

Safely get value with Type from JSON map. Will return null value when value was wrong.

safemap

Safely get value with Type from JSON map. Will return null value when value was wrong.

Feature

• 安全取值：可以从Map中连续使用[]操作符取值，任何错误取值都会返回null而不会报错。
• 安全的嵌套Map：你可以轻松取出深度嵌套Map中的数据，因为即使对Value为null的SafeMap使用[]操作符，也只会返回一个新的SafeMap(null)对象。
• 按类型取值：支持直接取出期望类型的数据，类型不正确就会返回null而不会报错。
• 类似Js的空值判断：通过调用isEmpty()方法，空数组，空字典，空字符串或0都会返回true，帮助你快速判断空值。

Getting Started

test('get value from safemap', () {
    // source map
    Map map = {
      'id': 3,
      'tag': 'student',
      'info': {
        'name': 'Jerry',
      },
      'class': [
        {
          "name": 'class 1',
          'tag': '',
        },
        {},
      ],
    };
    SafeMap safeMap = SafeMap(map);

    // 取值,错误的类型会返回SafeMap(null)
    assert(safeMap['id'].value == 3);
    assert(safeMap['id'].string == null);

    // 错误的下标也会返回SafeMap(null)
    assert(safeMap['tag'].value == 'student');
    assert(safeMap['tag12345'].value == null);

    // 连续取值,可以一直安全取值,只会返回SafeMap(null).
    assert(safeMap['info']['name'].value == 'Jerry');
    assert(safeMap['a']['b']['b']['b']['b']['b'].value == null);

    // 取出数组，也可以通过数组下标继续取值
    assert(safeMap['class'].list.length == 2);
    assert(safeMap['class'][0]['name'].value == 'class 1');

    // {},[],0,'',null 都会被判断为空
    assert(safeMap['class'][0]['tag'].isEmpty());
    assert(safeMap['class'][1].isEmpty());

    // 越界也会返回SafeMap(null)，判断isEmpty为true
    assert(safeMap['class'][2].isEmpty());
  });