相关疑难解决方法(0)

我有一个下拉列表，其中填充了从 API 接收的对象。问题是当用户进行编辑时，我无法使用对象预先填充下拉列表。

以下是 JSON 示例：

[{"_id":"435463","userId":"3423423","username":"ma","categoryId":"5656756","insurerId":"567544","packageId":"5675","categoryName":"vehicle insurance","insurerName":"lic","packageName":"family"},      {"_id":"4564644","userId":"2342344","username":"ma","categoryId":"6575744","insurerId":"567567","packageId":"3455","categoryName":"life insurance","insurerName":"lic","packageName":"family"}]
``


    import 'package:flutter/material.dart';
    import 'package:http/http.dart' as http;
    import 'package:intl/intl.dart';
    import 'dart:convert';

    UserPackages selectedPckg;
    class AddOrEditClaim extends StatefulWidget {
      @override
      AddOrEditClaimState createState() => AddOrEditClaimState();
    }

    class AddOrEditClaimState extends State<AddOrEditClaim> {
      List<UserPackages> packageList = List();
      final formKey = GlobalKey<FormState>();

      @override
      void initState() {
            fetchPackages();
            selectedPckg= UserPackages();
            UserPackages packgToEdit = new UserPackages();
            packgToEdit.packageId="123";
            packgToEdit.packageName="family";
            selectedPckg=packgToEdit;

             super.initState();
      }

      @override
      Widget build(BuildContext context) {
        // TODO: implement build
        return new Scaffold(
            appBar: AppBar(
              title: Text('Add …