pull down to REFRESH in Flutter

My dashboard code looks like this, Here I am doing get req in getReport method, I have added the RefreshIndicator in the code which when pulled down inside container should do the refresh, there I am calling my getData(), But I am not getting the refreshed content, I am adding my code below, let me know if anywhere I made a mistake.

below my dashboard.dart

class Window extends StatefulWidget {
  @override
  _WindowState createState() => _WindowState();
}

class _WindowState extends State<Window> {
  Future reportList;    
  @override
  void initState() {
    super.initState();
    reportList = getReport();
  }    

  Future<void> getReport() async {
    http.Response response =
        await http.get(reportsListURL, headers: {"token": "$token"});
    switch (response.statusCode) {
      case 200: 
        String reportList = response.body;
        var collection = json.decode(reportList);
        return collection;

      case 403:
          break;

      case 401:
        return null;

      default:
        return 1;
    }
  }

  getRefreshScaffold() {
    return Center(
      child: RaisedButton(
        onPressed: () {
          setState(() {
            reportList = getReport();
          });
        },
        child: Text('Refresh, Network issues.'),
      ),
    );
  }

  getDashBody(var data) {
    double maxHeight = MediaQuery.of(context).size.height;
    return Column(
      children: <Widget>[
        Container(
          height: maxHeight - 800,
        ),
        Container(
          margin: new EdgeInsets.all(0.0),
          height: maxHeight - 188,
          child: new Center(
          child: new RefreshIndicator(          //here I am adding the RefreshIndicator
          onRefresh:getReport,                  //and calling the getReport() which hits the get api
          child: createList(context, data),
          ),),
        ),
      ],
    );
  }

  Widget createList(BuildContext context, var data) {
    Widget _listView = ListView.builder(
      itemCount: data.length,
      itemBuilder: (context, count) {
        return createData(context, count, data);
      },
    );
    return _listView;
  }

  createData(BuildContext context, int count, var data) {
    var metrics = data["statistic_cards"].map<Widget>((cardInfo) {
      var cardColor = getColorFromHexString(cardInfo["color"]);
      if (cardInfo["progress_bar"] != null && cardInfo["progress_bar"]) {
        return buildRadialProgressBar(
          context: context,
          progressPercent: cardInfo["percentage"],
          color: cardColor,
          count: cardInfo["value"],
          title: cardInfo["title"],
        );
      } else {
        return buildSubscriberTile(context, cardInfo, cardColor);
      }
    }).toList();

    var rowMetrics = new List<Widget>();
    for (int i = 0; i < metrics.length; i += 2) {
      if (i + 2 < metrics.length)
        rowMetrics.add(Row(children: metrics.sublist(i, i + 2)));
      else
        rowMetrics.add(Row(children: [metrics[metrics.length - 1], Spacer()]));
    }
    return SingleChildScrollView(
      child: LimitedBox(
        //  maxHeight: MediaQuery.of(context).size.height / 1.30,
        child: Column(
          mainAxisSize: MainAxisSize.max,
          mainAxisAlignment: MainAxisAlignment.center,
          children: rowMetrics,
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: reportList,
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        switch (snapshot.connectionState) {
          case ConnectionState.none:
          case ConnectionState.waiting:
          case ConnectionState.active:
            return Center(
              child: CircularProgressIndicator(),
            );
          case ConnectionState.done:
            var data = snapshot.data;
            if (snapshot.hasData && !snapshot.hasError) {
              return getDashBody(data);
            } else if (data == null) {
              return Center(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    Text("Timeout! Log back in to continue"),
                    Padding(
                      padding: EdgeInsets.all(25.0),
                    ),
                    RaisedButton(
                      onPressed: () {
                        setState(() {
                          token = null;
                        });
                        Navigator.of(context).pushReplacement(
                          CupertinoPageRoute(
                              builder: (BuildContext context) => LoginPage()),
                        );
                      },
                      child: Text('Login Again!'),
                    ),
                  ],
                ),
              );
            } else {
              getRefreshScaffold();
            }
        }
      },
    );
  }
}

Basic RefreshIndicator Example

Below is a State class of a StatefulWidget, where:

• a ListView is wrapped in a RefreshIndicator
• numbersList state variable is its data source
• onRefresh calls _pullRefresh function to update data & ListView
• _pullRefresh is an async function, returning nothing (a Future<void>)
• when _pullRefresh's long running data request completes, numbersList member/state variable is updated in a setState() call to rebuild ListView to display new data

import 'package:flutter/material.dart';
import 'dart:math';

class PullRefreshPage extends StatefulWidget {
  const PullRefreshPage();

  @override
  State<PullRefreshPage> createState() => _PullRefreshPageState();
}

class _PullRefreshPageState extends State<PullRefreshPage> {
  List<String> numbersList = NumberGenerator().numbers;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: RefreshIndicator(
        onRefresh: _pullRefresh,
        child: ListView.builder(
          itemCount: numbersList.length,
          itemBuilder: (context, index) {
            return ListTile(
              title: Text(numbersList[index]),
            );
          },),
      ),
    );
  }

  Future<void> _pullRefresh() async {
    List<String> freshNumbers = await NumberGenerator().slowNumbers();
    setState(() {
      numbersList = freshNumbers;
    });
    // why use freshNumbers var? https://stackoverflow.com/a/52992836/2301224
  }
}

class NumberGenerator {
  Future<List<String>> slowNumbers() async {
    return Future.delayed(const Duration(milliseconds: 1000), () => numbers,);
  }

  List<String> get numbers => List.generate(5, (index) => number);


  String get number => Random().nextInt(99999).toString();
}

Notes

• If your async onRefresh function completes very quickly, you may want to add an await Future.delayed(Duration(seconds: 2)); after it, just so the UX is more pleasant.
• This gives time for the user to complete a swipe / pull down gesture & for the refresh indicator to render / animate / spin indicating data has been fetched.

FutureBuilder with RefreshIndicator Example

Here's another version of the above State<PullRefreshPage> class using a FutureBuilder, which is common when fetching data from a Database or HTTP source:

class _PullRefreshPageState extends State<PullRefreshPage> {
  late Future<List<String>> futureNumbersList;

  @override
  void initState() {
    super.initState();
    futureNumbersList = NumberGenerator().slowNumbers();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: FutureBuilder<List<String>>(
        future: futureNumbersList,
        builder: (context, snapshot) {
          return RefreshIndicator(
            child: _listView(snapshot),
            onRefresh: _pullRefresh,
          );
        },
      ),
    );
  }

  Widget _listView(AsyncSnapshot snapshot) {
    if (snapshot.hasData) {
      return ListView.builder(
        itemCount: snapshot.data.length,
        itemBuilder: (context, index) {
          return ListTile(
            title: Text(snapshot.data[index]),
          );
        },);
    }
    else {
      return Center(
        child: Text('Loading data...'),
      );
    }
  }

  Future<void> _pullRefresh() async {
    List<String> freshNumbers = await NumberGenerator().slowNumbers();
    setState(() {
      futureNumbersList = Future.value(freshNumbers);
    });
  }
}

Notes

• slowNumbers() function is the same as in the Basic Example above, but the data is wrapped in a Future.value() since FutureBuilder expects a Future, but setState() should not await async data
• according to Rémi, Collin & other Dart/Flutter demigods it's good practice to update Stateful Widget member variables inside setState() (futureNumbersList in FutureBuilder example & numbersList in Basic example), after its long running async data fetch functions have completed.
  • see https://stackoverflow.com/a/52992836/2301224
• if you try to make setState async, you'll get an exception
• updating member variables outside of setState and having an empty setState closure, may result in hand-slapping / code analysis warnings in the future