如何正确读取上下文(ModalRoute.of).settings.arguments？

Question

我对flutter感到困惑，当我想从statefulwidget (initstate)中读取参数并将其访问到widget build中时，该变量仍然为null。如何正确地阅读它？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

我知道错在哪里了，

因此，我创建了全局变量(标题、副标题)并从searchBarangRequest赋值，如下所示：

String title = ""；String subtitle = ""；

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();
  }
}

而且它工作得很完美！谢谢。