flutter - 如何正确阅读 ModalRoute.of(context).settings.arguments？

Question

我对 flutter 感到困惑，当我想从 statefulwidget (initstate) 读取参数并将其访问到小部件构建中时，该变量仍然为空。如何正确阅读？我的代码如下:

import 'package:flutter/material.dart';
import 'package:caritokoonline_v2/components/ResultForm.dart';
import 'package:caritokoonline_v2/podo/SearchBarangRequest.dart';

class ResultBarangActivity extends StatefulWidget {
  SearchBarangRequest searchBarangRequest;

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

class _ResultBarangActivityState extends State<ResultBarangActivity> {
  final _scaffoldKey = GlobalKey<ScaffoldState>();


  @override
  void initState(){


    Future.delayed(Duration.zero,(){
      setState(() {
        widget.searchBarangRequest = ModalRoute.of(context).settings.arguments;
        print(widget.searchBarangRequest.keyword);
      });
    });

    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    if (widget.searchBarangRequest == null) return Scaffold(); //this line is always executed

    return ResultForm(
      scaffoldKey: _scaffoldKey,
      title: widget.searchBarangRequest.keyword,
      subTitle: widget.searchBarangRequest.hargaRange.toString(),);
  }
}

谢谢!

Answer 1

我知道什么错误，

因此，我创建了全局变量(标题、副标题)并从 searchBarangRequest 分配值，如下代码所示:

字符串标题 = "";
字符串副标题 = "";

class _ResultBarangActivityState extends State<ResultBarangActivity> {
  final _scaffoldKey = GlobalKey<ScaffoldState>();


  @override
  void initState(){


    Future.delayed(Duration.zero,(){
      setState(() {
        widget.searchBarangRequest = ModalRoute.of(context).settings.arguments;
        title       = widget.searchBarangRequest.keyword;

        subtitle    = "${Utils().kondisiToString(widget.searchBarangRequest.kondisiBarang)} | ${widget.searchBarangRequest.hargaRange.toString()}";


        // print(widget.searchBarangRequest.keyword);

        getProducts(widget.searchBarangRequest);
      });
    });

    super.initState();
  }
}

它完美无缺!谢谢。