将数据传递给有状态的小部件 [英] Passing Data to a Stateful Widget

问题描述

我想知道在创建数据时将数据传递到有状态的小部件的推荐方法是什么。

I'm wondering what the recommended way of passing data to a stateful widget, while creating it, is.

我看到的两种样式是：

class ServerInfo extends StatefulWidget {

  Server _server;

  ServerInfo(Server server) {
    this._server = server;
  }

  @override
    State<StatefulWidget> createState() => new _ServerInfoState(_server);
}

class _ServerInfoState extends State<ServerInfo> {
  Server _server;

  _ServerInfoState(Server server) {
    this._server = server;
  }
}

此方法在<$ c $中都保留一个值c> ServerInfo 和 _ServerInfoState ，这似乎有点浪费。

This method keeps a value both in ServerInfo and _ServerInfoState, which seems a bit wasteful.

另一种方法是使用 widget._server ：

class ServerInfo extends StatefulWidget {

  Server _server;

  ServerInfo(Server server) {
    this._server = server;
  }

  @override
    State<StatefulWidget> createState() => new _ServerInfoState();
}

class _ServerInfoState extends State<ServerInfo> {
  @override
    Widget build(BuildContext context) {
      widget._server = "10"; // Do something we the server value
      return null;
    }
}

这似乎有些倒退，因为该州不再存储在 _ServerInfoSate 中，而是存储在小部件中。

This seems a bit backwards as the state is no longer stored in _ServerInfoSate but instead in the widget.

是否有最佳做法？

推荐答案

不要使用其构造函数将参数传递给 State 。
您只能使用 this.widget.myField 访问它们。

Don't pass parameters to State using it's constructor. You should only access these using this.widget.myField.

不仅编辑构造函数还需要大量的手工工作；它什么也没带来。没有理由重复小部件的所有字段。

Not only editing the constructor requires a lot of manual work ; it doesn't bring anything. There's no reason to duplicate all the fields of Widget.

EDIT：

下面是一个示例：

class ServerIpText extends StatefulWidget {
  final String serverIP;

  const ServerIpText ({ Key key, this.serverIP }): super(key: key);

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

class _ServerIpTextState extends State<ServerIpText> {
  @override
  Widget build(BuildContext context) {
    return Text(widget.serverIP);
  }
}

class AnotherClass extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: ServerIpText(serverIP: "127.0.0.1")
    );
  }
}

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