dependent dropdown

import 'dart:convert';

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  void initState() {
    _getLabList();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Dynamic DropDownList REST API'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.start,
        children: <Widget>[
          Container(
            alignment: Alignment.topCenter,
            margin: EdgeInsets.only(bottom: 100, top: 100),
            child: Text(
              'Depended Dropdown',
              style: TextStyle(fontWeight: FontWeight.w800, fontSize: 20),
            ),
          ),
          //======================================================== All Lab List

          Container(
            padding: EdgeInsets.only(left: 15, right: 15, top: 5),
            color: Colors.white,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: <Widget>[
                Expanded(
                  child: DropdownButtonHideUnderline(
                    child: ButtonTheme(
                      alignedDropdown: true,
                      child: DropdownButton<String>(
                        value: _myLab,
                        iconSize: 30,
                        icon: (null),
                        style: TextStyle(
                          color: Colors.black54,
                          fontSize: 16,
                        ),
                        hint: Text('Select State'),
                        onChanged: (String newValue) {
                          setState(() {
                            _myLab = newValue;
                            _myTest = null;
                            _getTestList();
                            print(_myLab);
                          });
                        },
                        items: allLabList?.map((item) {
                              return new DropdownMenuItem(
                                child: new Text(item['PartnerName']),
                                value: item['EncPartnerId'].toString(),//=====id/encid here
                              );
                            })?.toList() ??
                            [],
                      ),
                    ),
                  ),
                ),
              ],
            ),
          ),
          SizedBox(
            height: 30,
          ),

          //======================================================== Test List depends on Lab

          Container(
            padding: EdgeInsets.only(left: 15, right: 15, top: 5),
            color: Colors.white,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: <Widget>[
                Expanded(
                  child: DropdownButtonHideUnderline(
                    child: ButtonTheme(
                      alignedDropdown: true,
                      child: DropdownButton<String>(
                        value: _myTest,//===============
                        iconSize: 30,
                        icon: (null),
                        style: TextStyle(
                          color: Colors.black54,
                          fontSize: 16,
                        ),
                        hint: Text('Select City'),
                        onChanged: (String newValue) {
                          setState(() {
                            _myTest = newValue;
                            print(_myTest);
                          });
                        },
                        items: testList?.map((item) {
                              return new DropdownMenuItem(
                                child: new Text(item['TestName']),
                                value: item['TestId'].toString(),//============
                              );
                            })?.toList() ??
                            [],
                      ),
                    ),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  //=============================================================================== Api Calling here

//CALLING LAB API HERE
// Get LAB information by API
  List allLabList;
  String _myLab;

  String allLabInfoUrl = 'http://medbo.digitalicon.in/api/medboapi/AllPathLab';
  Future<String> _getLabList() async {
    await http.post(allLabInfoUrl,  body: {

    }).then((response) {
      var data = json.decode(response.body);

//      print(data);
      setState(() {
        allLabList = data['Partner'];
      });
    });
  }

  // Get TEST information by API
  List testList;
  String _myTest;

  String allTestInfoUrl ='http://medbo.digitalicon.in/api/medboapi/GetTestByLab';
  Future<String> _getTestList() async {
    await http.post(allTestInfoUrl,  body: {

      "TestId": _myLab,
    }).then((response) {
      var data = json.decode(response.body);

      setState(() {
        testList = data['Data'];
      });
    });
  }
}








// My Json Response for all Lab

{
    "Status": "1",
    "Message": "",
    "Partner": [
        {
            "EncPartnerId": "IujyQXg8KZg8asLvK/FS7g==",
            "PartnerName": "dasfdsf"
        },
        {
            "EncPartnerId": "pEl2B9kuumKRxIxLJO76eQ==",
            "PartnerName": "partner172"
        },
        {
            "EncPartnerId": "eYwtNBXR6P/JDtsIwr+Bvw==",
            "PartnerName": "nnkb"
        },
        {
            "EncPartnerId": "kFgorcFF0G6RQD4W+LwWnQ==",
            "PartnerName": "nnkjj"
        },
        {
            "EncPartnerId": "U4exk+vfMGrn7cjNUa/PBw==",
            "PartnerName": "mahadev"
        },
        {
            "EncPartnerId": "tqkaSjTFgDf0612mp9mbsQ==",
            "PartnerName": null
        },
        {
            "EncPartnerId": "0aruO0FbYOu5IerRBxdT8w==",
            "PartnerName": "Suraksha Diagnostics"
        },
        {
            "EncPartnerId": "65gtodyhbtdInTsJWr1ZkA==",
            "PartnerName": "Rasomoy pvt. Hospital"
        },
        {
            "EncPartnerId": "LEuT1eIlpLEMAAkZme3wpQ==",
            "PartnerName": "Tangra medical House"
        },
        {
            "EncPartnerId": "q8O8YMzYKXSB4RtkX4k7Lw==",
            "PartnerName": "Partner new"
        }
    ]
}



//And depending upon Lab my  Test response 

{
    "Status": "1",
    "Message": "",
    "Data": [
        {
            "TestId": "I3uXyzcuDZf21SSe5fHnSQ==",
            "EncTestId": null,
            "TestName": "RT-PCR",
            "NoOfPartner": null,
            "TestFee": null,
            "DiscountedFee": null,
            "BookingFee": null,
            "ReportTime": null,
            "Note": null,
            "CreateBy": null,
            "CreateDate": null,
            "ModBy": null,
            "ModDate": null,
            "ActiveStatus": null,
            "Permission": null
        },
        {
            "TestId": "I3uXyzcuDZf21SSe5fHnSQ==",
            "EncTestId": null,
            "TestName": "RT-PCR",
            "NoOfPartner": null,
            "TestFee": null,
            "DiscountedFee": null,
            "BookingFee": null,
            "ReportTime": null,
            "Note": null,
            "CreateBy": null,
            "CreateDate": null,
            "ModBy": null,
            "ModDate": null,
            "ActiveStatus": null,
            "Permission": null
        },
        {
            "TestId": "I3uXyzcuDZf21SSe5fHnSQ==",
            "EncTestId": null,
            "TestName": "RT-PCR",
            "NoOfPartner": null,
            "TestFee": null,
            "DiscountedFee": null,
            "BookingFee": null,
            "ReportTime": null,
            "Note": null,
            "CreateBy": null,
            "CreateDate": null,
            "ModBy": null,
            "ModDate": null,
            "ActiveStatus": null,
            "Permission": null
        }
    ]
}