[U8.1] DatePicker和TimePicker设置默认字符串 [英] [U8.1] DatePicker and TimePicker setting default string
问题描述
默认情况下，UWA 8.1 for Windows Store和Windows Phone（WinRT）中的DatePicker和TimePicker显示今天的日期和当前时间，其中我想将最初的控件设置为某个默认字符串让我们说" ;设置到期日期/时间"因为它们是
可选。
DatePicker and TimePicker in UWA 8.1 for Windows Store and Windows Phone (WinRT) by default it shows today date and current time, where as I want to set initially both the controls to some default string let's say "Set Due Date/Time" because they're optional.
我只使用MVVM模式和MVVM光库将它们绑定到以下属性
I am binding them to the following properties using MVVM pattern and MVVM light libraries only
public DateTimeOffset? DueDate { get; set; }
public TimeSpan? DueTime { get; set; }
我已经尝试过以下方式，如果有任何其他选择请建议。
I've tried in the following way, if any other alternatives please suggest.
我使用了两个转换器但是有一个问题，当我点击"Set"按钮时截止日期"然后单击日期选择器（弹出/选择屏幕）中的刻度线而不更改转换器不会触发的日期，月份或年份，当我更改
到日期，月份或年份然后它会触发，我看到了即使属性绑定是可为空的DateTimeOffset，XAML中的DatePicker显示Date值到当前日期，IsHitTestVisible =" False"移除倾斜效果，这是很好的，因为
按钮无法再点击，但倾斜效果对我来说不是必须的选项
I have used two converters but there is a problem, when I click the button that says "Set Due Date" and click the tick mark in the datepicker (popup/selection screen) without changing date, month or year the converter doesn't fire, when I make a change
to date, month or year then it fires, I see that even if the property bound is a nullable DateTimeOffset the DatePicker in XAML shows Date value to current date, also IsHitTestVisible="False" removes the tilt effect which is nice to have, because
the button can't be clicked anymore, but the tilt effect is not a must have option for me
<Page
x:Class="UWP.MVVM.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:UWP.MVVM"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:vm="using:UWP.MVVM.ViewModels"
xmlns:interactivity="using:Microsoft.Xaml.Interactivity"
xmlns:core="using:Microsoft.Xaml.Interactions.Core"
xmlns:converters="using:UWP.MVVM.Converters"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Page.Resources>
<converters:DateTimeOffsetToVisibilityConverter x:Key="DateTimeOffsetToVisibilityConverter"/>
<converters:DateTimeOffsetToOpacityConverter x:Key="DateTimeOffsetToOpacityConverter"/>
</Page.Resources>
<Grid Margin="24,24">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBox Header="First Name"
Text="{Binding Person.FirstName}"/>
<DatePicker Name="DateOfBirth"
Date="{Binding Person.DateOfBirth, Mode=TwoWay}"
Grid.Row="1"
Opacity="{Binding Person.DateOfBirth, Converter={StaticResource DateTimeOffsetToOpacityConverter}}"/>
<Button Grid.Row="1"
Content="Set Due Date"
IsHitTestVisible="False"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
Visibility="{Binding Person.DateOfBirth, Converter={StaticResource DateTimeOffsetToVisibilityConverter}}"/>
</Grid>
</Page>
namespace UWP.MVVM.Converters
{
using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Data;
public class DateTimeOffsetToVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
if (value == null)
{
return Visibility.Visible;
}
else
{
return Visibility.Collapsed;
}
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
if (value == Visibility.Visible)
{
return null;
}
else
{
return DateTimeOffset.Now;
}
}
}
}
namespace UWP.MVVM.Converters
{
using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Data;
public class DateTimeOffsetToOpacityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
if (value == null)
{
return 0D;
}
else
{
return 1D;
}
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
if (value == 0D)
{
return null;
}
else
{
return DateTimeOffset.Now;
}
}
}
}
推荐答案
Hi MohammedAbdulMateen，
Hi MohammedAbdulMateen,
请阅读粘贴帖子，尤其是
发布指南：主题行标签和
Windows 10 SDK和工具的已知问题
Please read the sticky posts, especially the Guide to posting: subject line tags and Known Issues for Windows 10 SDK and Tools
根据您的代码段，我无法重现您的问题。因为我没有看到你如何在按钮点击命令处理程序中设置"截止日期"。
Based on your code snippet, I could not reproduce your issue. Because I have not saw that you how to set "Due Date" in button click command handler.
但我已经制作了一个代码样本进行测试，它运行良好。请参考我的以下代码来检查您的代码：
But I have made a code sample to test, it worked well. Please refer to my following code to check your code:
<Grid Margin="24,24">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBox Header="First Name"
Text="{Binding person.FirstName}"/>
<DatePicker Name="DateOfBirth"
Date="{Binding person.DateOfBirth, Mode=TwoWay}"
Grid.Row="1"
Opacity="{Binding person.DateOfBirth, Converter={StaticResource DateTimeOffsetToOpacityConverter}}"/>
<Button Grid.Row="2"
Content="Set Due Date"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
Visibility="{Binding person.DateOfBirth, Converter={StaticResource DateTimeOffsetToVisibilityConverter}}">
<interactivity:Interaction.Behaviors>
<core:EventTriggerBehavior EventName="Click">
<core:InvokeCommandAction Command="{Binding ButtonClick}"/>
</core:EventTriggerBehavior>
</interactivity:Interaction.Behaviors>
</Button>
<Button Content="Click Me!"
Grid.Row="3">
<interactivity:Interaction.Behaviors>
<core:EventTriggerBehavior EventName="Click">
<core:InvokeCommandAction Command="{Binding ButtonClick}"/>
</core:EventTriggerBehavior>
</interactivity:Interaction.Behaviors>
</Button>
</Grid>
public class MainViewModel : ViewModelBase
{
/// <summary>
/// Initializes a new instance of the MainViewModel class.
/// </summary>
public MainViewModel()
{
person = new Person() {FirstName="test1" };
ButtonClick = new RelayCommand(ButtonHandler);
}
private Person _person;
public Person person
{
get { return _person; }
set
{
_person = value;
RaisePropertyChanged("person");
}
}
public RelayCommand ButtonClick { get; set; }
protected void ButtonHandler()
{
Debug.WriteLine("button click");
person.DateOfBirth = DateTime.Now;
}
}
public class MainViewModel : ViewModelBase
{
/// <summary>
/// Initializes a new instance of the MainViewModel class.
/// </summary>
public MainViewModel()
{
person = new Person() {FirstName="test1" };
ButtonClick = new RelayCommand(ButtonHandler);
}
private Person _person;
public Person person
{
get { return _person; }
set
{
_person = value;
RaisePropertyChanged("person");
}
}
public RelayCommand ButtonClick { get; set; }
protected void ButtonHandler()
{
Debug.WriteLine("button click");
person.DateOfBirth = DateTime.Now;
}
}
public class Person:ViewModelBase
{
private string _FirstName;
public string FirstName
{
get { return _FirstName; }
set
{
_FirstName = value;
RaisePropertyChanged("FirstName");
}
}
private DateTimeOffset? _DateOfBirth;
public DateTimeOffset? DateOfBirth
{
get { return _DateOfBirth; }
set
{
_DateOfBirth = value;
RaisePropertyChanged("DateOfBirth");
}
}
}
public MainPage()
{
this.InitializeComponent();
this.DataContext = new MainViewModel();
}最好的问候，
Xavier Eoro
Xavier Eoro
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