Question

我有时间选择器返回TimeOfDay对象但我已将该值保存在数据库中，作为从DateTime.millisecondsSinceEpoch

获得的毫秒整数

Answer 1

这是不可能的。 TimeOfDay仅小时和分钟。虽然DateTime也有日/月/年

如果要转换它，则需要更多信息。比如当前的DateTime。然后将两者合并为一个最终日期时间。

TimeOfDay t;
final now = new DateTime.now();
return new DateTime(now.year, now.month, now.day, t.hour, t.minute);

Answer 2

您可以使用DateTime扩展名

extension DateTimeExtension on DateTime {
  DateTime applied(TimeOfDay time) {
    return DateTime(year, month, day, time.hour, time.minute);
  }
}

然后您可以像这样使用它：

final dateTime = yourDate.applied(yourTimeOfDayValue);

并将pubspec.yaml中的sdk版本更改为

environment:
 sdk: ">=2.7.0 <3.0.0"

Answer 3

您可以使用这种扩展名，也可以在单独的文件（如dateTime_extensions.dart）中添加更多扩展名方法，以使以后的项目工作变得轻松

文件： dateTime_extensions.dart;


extension DateTimeExtension on DateTime {
DateTime setTimeOfDay(TimeOfDay time) {
    return DateTime(this.year, this.month, this.day, time.hour, time.minute);
  }

  DateTime setTime(
      {int hours = 0,
      int minutes = 0,
      int seconds = 0,
      int milliSeconds = 0,
      int microSeconds = 0}) {
    return DateTime(this.year, this.month, this.day, hours, minutes, seconds,
        milliSeconds, microSeconds);
  }

  DateTime clearTime() {
    return DateTime(this.year, this.month, this.day, 0, 0, 0, 0, 0);
  }

   ///..... add more methods/properties for your convenience 
}

像这样使用它


import 'package:your_app/dateTime_extensions.dart';

    date.clearTime(); //to clear timeSpan
    date.setTime(); //also be used to clear time if you don't provide any parameters
    date.setTime(hours: 16,minutes: 23,seconds: 24); // will set time to existing date eg. existing_date 16:23:24
    date.setTimeOfDay(TimeOfDay(hour: 16, minute: 59));

Answer 4

这只是连接 var options = { type: 'line', data: { labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"], datasets: [{ label: '# of Votes', data: [100, 19, 3, 5, -10, 3], borderColor: 'red', backgroundColor: 'red' }, { label: '# of Votes2', data: [20, 10, 4, 3, -30, 32], borderColor: 'blue', backgroundColor: 'blue' } ] }, options: { plugins: { backgrounds: { hbars: [{ from: 0, to: 'MIN', color: "rgb(230, 195, 195)" }] } } }, plugins: [{ id: 'backgrounds', beforeDraw: (chart, args, options) => { const { canvas, ctx, chartArea, scales: { y } } = chart; let from = 0; let to = 0; options.hbars.forEach((hBar) => { from = hBar.from; to = hBar.to; from = from === 'MIN' ? y.min : from; from = from === 'MAX' ? y.max : from; to = to === 'MIN' ? y.min : to; to = to === 'MAX' ? y.max : to; ctx.save(canvas.width, canvas.height); ctx.fillStyle = hBar.color; ctx.fillRect(chartArea.left, y.getPixelForValue(from), chartArea.right - chartArea.left, y.getPixelForValue(to) - y.getPixelForValue(hBar.from)); ctx.restore(); }) } }] } var ctx = document.getElementById('chartJSContainer').getContext('2d'); new Chart(ctx, options); 和 <body> <canvas id="chartJSContainer" width="600" height="400"></canvas> <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.4.0/chart.js"></script> </body> 的一个小方法：

DateTime

如何将flutter TimeOfDay转换为DateTime？

4 个答案: