如何从DropdownButtonFormField获取两个值

class MyDataModel {
  final String value1;
  final String value2;

  MyDataModel(this.value1, this.value2);
}

MyDataModel selectedValues;

DropdownButtonFormField<MyDataModel>(
  value: selectedValues,
  onChanged: (MyDataModel newValue) {
    setState(() {
      selectedValues = newValue;
    });
  },
  items: [
    DropdownMenuItem<MyDataModel>(
      value: MyDataModel('Value 1', 'Value A'),
      child: Text('Option 1'),
    ),
    DropdownMenuItem<MyDataModel>(
      value: MyDataModel('Value 2', 'Value B'),
      child: Text('Option 2'),
    ),
    // 添加更多的选项...
  ],
),

String value1 = selectedValues.value1;
String value2 = selectedValues.value2;