Class 'int' has no instance getter 'millisecondsSinceEpoch'

Question

i want to build a syncfusion chart in flutter. i retrive data from firebase realtime database. the data would be show in the chart. and i got a problem here. they say about 'millisecondsSinceEpoch'. but i don't have it in my code. but there's got a problem. this is my code :

import 'dart:async';

import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_charts/charts.dart';

class Chart extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: HolyChart(),
      ),
    );
  }
}

class HolyChart extends StatefulWidget {
  @override
  _HolyChartState createState() => _HolyChartState();
}

class _HolyChartState extends State<HolyChart> {
  Timer _timer;
  int _count = 0;
  ChartSeriesController _seriesController;
  final _dbReference = FirebaseDatabase.instance.reference();
  List _chartData = <ChartData>[];
  int _values;

  @override
  void dispose() {
    _timer?.cancel();
    super.dispose();
  }

  _updateData(Timer timer) {
    _chartData.add(ChartData(_count, _values));

    if (_chartData.length == 20) {
      _chartData.removeAt(0);
      _seriesController.updateDataSource(
          addedDataIndexes: <int>[_chartData.length - 1],
          removedDataIndexes: <int>[0]);
    }

    _count = _count + 1;
  }

  @override
  Widget build(BuildContext context) {
    return StreamBuilder(
      stream: _dbReference.child("Data").onValue,
      builder: (context, snapshot) {
        Widget widget;

        if (snapshot.hasData &&
            !snapshot.hasError &&
            snapshot.data.snapshot.value != null) {
          _values = snapshot.data.snapshot.value["Moisture"];

          if (_values != null) {
            _timer = Timer.periodic(Duration(seconds: 3), _updateData(_timer));
          }

          widget = Container(
            child: SfCartesianChart(
              tooltipBehavior: TooltipBehavior(enable: true),
              primaryXAxis: DateTimeAxis(),
              series: <LineSeries<ChartData, int>>[
                LineSeries<ChartData, int>(
                  dataSource: _chartData,
                  xValueMapper: (ChartData data, _) => data.xAxisValue,
                  yValueMapper: (ChartData data, _) => data.yAxisValue,
                )
              ],
            ),
          );
        } else {
          widget = Center(child: CircularProgressIndicator());
        }

        return widget;
      },
    );
  }
}

class ChartData {
  ChartData(this.xAxisValue, this.yAxisValue);
  ChartData.fromMap(this.xAxisValue, this.yAxisValue);

  final int xAxisValue;
  final int yAxisValue;
}

and this is the problem for my code. what's mean with the function 'millisecondsSinceEpoch'? b

The following NoSuchMethodError was thrown building LayoutBuilder:
Class 'int' has no instance getter 'millisecondsSinceEpoch'.
Receiver: 0
Tried calling: millisecondsSinceEpoch

can anyone help me?? thank you so much for your help...

Answer 1

My guess is that you use primaryXAxis: DateTimeAxis(), but none of your x/y value is a Date. The SfCartesianChart tries to convert x or y as a date (millisecondsSinceEpoch is relative to the usage of a date) but both of them are int.

Have a look at this (search for DateTimeAxis, there is different examples) : https://help.syncfusion.com/flutter/cartesian-charts/axis-customization

Answer 2

Thanks for the interest in our Flutter charts. We have analyzed your query and the given code and would like to tell you that you are using the DateTimeAxis for the primaryXAxis but your data source values are not a DateTime value. So, kindly use NumericAxis in the chart to process numeric data. To know more about our charts, please find the help document.

Thanks, Dharanitharan. P