无法在初始化程序中访问实例成员“小部件”

Question

在我的项目中，我使用以下代码将数据从一个小部件传递到另一个小部件：

Navigator.push(
          context,
          MaterialPageRoute(
            builder: (context) =>
                TranslatorSignUpStep2(transModel: this._translatorModel),
          ),
        );

然后我通过下面的代码在另一个小部件中检索它：

class TranslatorSignUpStep2 extends StatefulWidget {
  final TranslatorModel transModel;
  TranslatorSignUpStep2({this.transModel});

  @override
  _TranslatorSignUpStep2State createState() => _TranslatorSignUpStep2State();
}

问题是，在 TranslatorSignUpStep2 类中，我想将传入的transModel变量分配给另一个变量，因此我编写了此代码

class _TranslatorSignUpStep2State extends State<TranslatorSignUpStep2> {
  TranslatorModel _translatorModel = widget.transModel;
}

但似乎widget不能在构建方法之外使用，所以我收到错误消息 The instance member 'widget' can't be accessed in an initializer.。有谁知道如何克服这个？

Answer 1

只需在初始化时添加关键字即可late：

class TranslatorSignUpStep2 extends StatefulWidget {
  final TranslatorModel transModel;
  TranslatorSignUpStep2({this.transModel});

  @override
  _TranslatorSignUpStep2State createState() => _TranslatorSignUpStep2State();
}

class _TranslatorSignUpStep2State extends State<TranslatorSignUpStep2> {
  late TranslatorModel _translatorModel = widget.transModel;
}

Answer 2

您可以像这样在 initState 函数中访问小部件。

class _TranslatorSignUpStep2State extends State<TranslatorSignUpStep2> {
  TranslatorModel _translatorModel ;

@override
void initState() {
_translatorModel = widget.transModel;
}

}

Answer 3

试试这个代码：

翻译者注册Step2 :

    class TranslatorSignUpStep2 extends StatefulWidget {
      final TranslatorModel transModel;
      TranslatorSignUpStep2({this.transModel});

      @override
      _TranslatorSignUpStep2State createState() => _TranslatorSignUpStep2State(this.transModel);
    }

TranslatorSignUpStep2 类：

  class _TranslatorSignUpStep2State extends State<TranslatorSignUpStep2> {
   _TranslatorSignUpStep2State(TranslatorModel _tempModel ){
    this._translatorModel =_tempModel;
    };
     TranslatorModel _translatorModel ;
    }