WPF显示年龄从datepicker使用数据绑定

我有一点window与datepicker和label。目标是显示出生日期被挑选的人的年龄。我正在使用MVVM light，我需要使用ViewModel.cs。我可以只用XAML吗？如果不是，如何解决这个问题？WPF显示年龄从datepicker使用数据绑定

我的视图模型：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using GalaSoft.MvvmLight; 
using System.Windows.Controls; 

namespace zh1_beteges 
{ 
    public class PatientVM : ViewModelBase 
    { 
     Patient b = null; 

     int age; 
     DatePicker DP; 
     public int Age 
     { 
      get { return age; } 
      set { Set(ref age, value); } 
     } 
     public Patient B 
     { 
      get 
      { 
       return b; 
      } 
      set { Set(ref b, value); } 
     } 
     public PatientVM(DatePicker DP) 
     { 
      this.DP = DP; 
     } 
     public PatientVM(Patient b, DatePicker DP) 
     { 
      this.B = b; 
      this.DP = DP; 
      age = DateTime.Today.Year - b.DateOfBirth.Year; 
     } 


    } 
}

和我的XAML：

<Window x:Class="zh1_beteges.BetegAdatai" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:local="clr-namespace:zh1_beteges" 
    mc:Ignorable="d" 
    Title="BetegAdatai" Height="314.894" Width="512.766" 
    WindowStartupLocation="CenterScreen" 
    > 
<Grid> 
    <Grid.RowDefinitions> 
     <RowDefinition Height="*"/> 
     <RowDefinition Height="*"/> 
     <RowDefinition Height="*"/> 
     <RowDefinition Height="*"/> 
     <RowDefinition Height="*"/> 
     <RowDefinition Height="*"/> 
     <RowDefinition Height="*"/> 
    </Grid.RowDefinitions> 
    <Grid.ColumnDefinitions> 
     <ColumnDefinition Width="*"/> 
     <ColumnDefinition Width="*"/> 
     <ColumnDefinition Width="0.7*"/> 
     <ColumnDefinition Width="0.7*"/> 
    </Grid.ColumnDefinitions> 
    <Label Content="Patient name:" HorizontalAlignment="Left" VerticalAlignment="Center" 
      FontSize="14" Margin="10,0,10,0" Grid.Row="0" Grid.Column="0"> 
    </Label> 
    <Label Content="PlaceOfBirth: " HorizontalAlignment="Left" VerticalAlignment="Center" 
      FontSize="14" Margin="10,0,10,0" Grid.Row="1" Grid.Column="0"> 
    </Label> 
    <Label Content="date of birth:" HorizontalAlignment="Left" VerticalAlignment="Center" 
      FontSize="14" Margin="10,0,10,0" Grid.Row="2" Grid.Column="0"> 
    </Label> 
    <Label Content="TAJ:" HorizontalAlignment="Left" VerticalAlignment="Center" 
      FontSize="14" Margin="10,0,10,0" Grid.Row="3" Grid.Column="0"> 
    </Label> 
    <Label Content="Age:" HorizontalAlignment="Left" VerticalAlignment="Center" 
      FontSize="14" Margin="10,0,10,0" Grid.Row="2" Grid.Column="2"> 
    </Label> 
    <Label Content="{Binding Path=Age}" HorizontalAlignment="Left" VerticalAlignment="Center" 
      FontSize="14" Margin="10,0,10,0" Grid.Row="2" Grid.Column="3"> 
    </Label> 
    <Button HorizontalAlignment="Stretch" VerticalAlignment="Stretch" 
      Grid.Row="5" Grid.Column="0" Grid.ColumnSpan="4" Margin="170,5,170,5" 
      Content="OK" FontSize="14"> 
    </Button> 
    <DatePicker x:Name="DP" Grid.Row="2" Grid.Column="1" HorizontalAlignment="Center" 
       VerticalAlignment="Center" DisplayDateStart="2016/01/01" 
       SelectedDate="{Binding Path=B.SzuletesiDatum}"> 
    </DatePicker> 
    <TextBox Margin="10,5,10,5" Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="3" 
      Text="{Binding Path=B.Name}" VerticalContentAlignment="Center" > 
    </TextBox> 
    <TextBox Margin="10,5,10,5" Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="3" 
      Text="{Binding Path=B.PlaceOfBirth}" VerticalContentAlignment="Center" > 
    </TextBox> 
    <TextBox Margin="10,5,10,5" Grid.Row="3" Grid.Column="1" Grid.ColumnSpan="3" 
      Text="{Binding Path=B.TAJ}" VerticalContentAlignment="Center"> 
    </TextBox> 
</Grid>

而且我Xaml.cs：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Data; 
using System.Windows.Documents; 
using System.Windows.Input; 
using System.Windows.Media; 
using System.Windows.Media.Imaging; 
using System.Windows.Shapes; 

namespace zh1_beteges 
{ 
    /// <summary> 
    /// Interaction logic for PatientData.xaml 
    /// </summary> 
    public partial class PatientData : Window 
    { 
     public PatientVM bvm; 
     public PatientData() 
     { 
      InitializeComponent(); 
      bvm = new PatientVM(DP); 
      this.DataContext = bvm; 
     } 
     public PatientData(Patient b) 
     { 
      InitializeComponent(); 
      bvm = new PatientVM(b,DP); 
      this.DataContext = bvm; 
     } 
    } 
}

来源

2016-11-05 agiro

是的，你可以使用自定义做到这一点转换器。自定义转换器允许您将数据绑定到转换为或来自该数据的另一个值。在你的情况下，你需要一个转换器，将选定的日期转换为该日期过去的时间。

您应该创建这样一个类：

public class DatetimeToPassedDateConverter : IValueConverter,MarkupExtension 
{ 
    public object Convert(object value, Type targetType, 
     object parameter, CultureInfo culture) 
    { 
     if(value is DateTime) 
      return DateTime.Now-(DateTime)value; 
     else 
      return null; 
    } 

    public object ConvertBack(object value, Type targetType, 
     object parameter, CultureInfo culture) 
    { 
     // Convert back which is not required in your case 
    } 

    public override object ProvideValue(IServiceProvider serviceProvider) 
    { 
     return this; 
    } 
}

，然后用它在你的XAML这样的：

<Label Content="{Binding ElementName=DP,Path=SelectedDate,Converter={namespace:DatetimeToPassedDateConverter}}" HorizontalAlignment="Left" VerticalAlignment="Center" 
     FontSize="14" Margin="10,0,10,0" Grid.Row="2" Grid.Column="3"> 
</Label>

更多有关自定义转换看this article。

来源

2016-11-05 10:22:57 Emad

感谢您的提示。我创建了一个类并添加了这个标签，但是我得到了一些'没有找到名称空间'。如何将其添加到'XAML'代码中？ – agiro

请参阅您的xaml页面的顶部。在最初的部分中，您会看到一些“xmlns：xxx = yyy”。遵循相同的语法，并在那里为你的班级添加命名空间 – Emad

根据你所链接的教程立即尝试。转换后的类位于命名空间内，我的其他所有东西都是公有的，没有运气。我这样做BTW： ' <地方：DatetimeToPassedDateConverter X：键= “dateConverter”/> ' – agiro

您可以创建属性里面PatientVM称为SelectedDate：

private DateTime? selectedDate; 
public DateTime? SelectedDate 
{ 
    get 
    { 
     return selectedDate; 
    } 
    set 
    { 
     selectedDate = value; 
     RaisePropertyChanged("SelectedDate"); 
     DateSelectionChangedExecute(); 
    } 
}

然后在DateSelectionChangedExecute计算Age（此方法例如应当加以改进，以防止负面年龄）：

private void DateSelectionChangedExecute() 
{ 
    if (SelectedDate != null && SelectedDate.Value != null) 
     Age = DateTime.Now.Year - SelectedDate.Value.Year; 
}

和绑定SelectedDate到您的DatePicker xaml：

<DatePicker x:Name="DP" Grid.Row="2" Grid.Column="1" HorizontalAlignment="Center" 
       VerticalAlignment="Center" DisplayDateStart="2016/01/01" 
       SelectedDate="{Binding SelectedDate}"> 
</DatePicker>

感谢此次每SelectedDate更改Age将被计算。

来源

2016-11-05 10:58:39 SteppingRazor

感谢您的帮助，但在@Emad的帮助下，我可以让他的解决方案工作。 – agiro

WPF显示年龄从datepicker使用数据绑定

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