Flutter 基于颤振中底部板材内的列表创建下拉列表

在我的代码中，我解析Json并创建一个映射列表，对于每个映射，我希望在下拉列表中显示它们

这是我的代码

import 'package:flutter/material.dart';

class ReportFilter extends StatefulWidget {
  final Map jsonString;
  var globalData;

  ReportFilter({@required this.jsonString, this.globalData});

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

class _ReportFilterState extends State<ReportFilter> {
  List<TextEditingController> controllers = [];
  TextEditingController controller;
  Map<String, Object> globalValues = Map<String, Object>();

  String type;
  int optionId;

  @override
  void initState() {
    globalValues = widget.globalData;
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: SingleChildScrollView(
          child: Column(
        children: <Widget>[
          Align(
              alignment: Alignment.topRight,
              child: FlatButton.icon(
                label: Text('Filters'),
                icon: Icon(Icons.filter_list),
                onPressed: () => showModalSheet(),
              )),
        ],
      )),
    );
  }

  showModalSheet() {
    List<Map<String, Object>> dropdownList = List<Map<String, Object>>();

       // here I am fetching data from json and doing some operations and storing the result into the List of maps, i.e dropdownList
// below I showed the contents of the dropdownList, and I am passing this list to the Dropdown menu. The contents of the list is dynamic and it keeps changing, It may contains any no of type value as String in  map, or List in map

    showModalBottomSheet<void>(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10.0),
        ),
        context: context,
        builder: (BuildContext context) {
          return StatefulBuilder(
              builder: (BuildContext context, StateSetter state) {
              return createBox(context, dropdownList, state);

          });
        });
  }

  createBox(BuildContext context, List<Map<String, Object>> val,
      StateSetter setState) {
    Widget supporting = buildSupportingWidget(val, setState);
    return SingleChildScrollView(
        child: LimitedBox(
            maxHeight: 300,
            child: Column(
                mainAxisSize: MainAxisSize.max,
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  buildMainDropdown(val, setState),
                  if (supporting != null) supporting
                ])));
  }

  Expanded buildMainDropdown(
      List<Map<String, Object>> items, StateSetter setState) {
    return Expanded(
      child: DropdownButtonHideUnderline(
        child: DropdownButton(
          value: type,
          hint: Text("Select a type"),
          items: items
              .map((json) => DropdownMenuItem(
                  child: Text(json["displayName"]), value: json["type"]))
              .toList(),
          onChanged: (newType) {
            setState(() {
              type = newType;
            });
          },
        ),
      ),
    );
  }

  Widget buildSupportingWidget(
      List<Map<String, Object>> items, StateSetter setState) {
    if (type == "list") {
      List<Map<String, Object>> options = items[1]["data"];
      return Expanded(
        child: DropdownButtonHideUnderline(
          child: DropdownButton(
            value: optionId,
            hint: Text("Select an entry"),
            items: options
                .map((option) => DropdownMenuItem(
                    child: Text(option["displayId"]), value: option["id"]))
                .toList(),
            onChanged: (newId) => setState(() {
              this.optionId = newId;
            }),
          ),
        ),
      );
    } else if (type == "string") {
      return Expanded(child: TextFormField());
    }
    return null;
  }
}

它可以是多个字符串，也可以是列表，具体取决于我正在处理的Json

然后我将列表传递给创建框，在那里我调用下拉函数，但我不知道如何基于列表创建这些下拉列表，并且在用户选择特定项后管理最终数据

比如，如果第一个下拉列表中的用户选择了一个需要文本框的项目，我需要将输入的值存储在某个地方，如果他从第一个下拉列表中选择了列表，结果显示了另一个下拉列表，我需要将这两个数据存储在某个地方。

---

如果有人以前做过类似的事情，或者有人知道这一点，请让我知道，谢谢

您可以通过只共享相关代码（而不是额外代码）和总结您的目标来简化您的问题。在这种情况下，人们更有可能回答你的问题。因为您的代码和解释都有点冗长，这取决于您想要的内容的复杂性。好的，我会编辑这个问题

[
      {
        "displayName": "Enter value",
        "type": "string",
      },
      {
        "displayName": "Enter second value",
        "type": "string",
      },
      {
        "id": "si",
        "displayName": "Source",
        "type": "list",
        "value": ["MO"], "searchField": "si",
        "data": [
          {"id": 1, "displayId": "MO"},
          {"id": 2, "displayId": "AO"},
          {"id": 3, "displayId": "OffNet"}
        ]
      }
    ];