WPF UserControl:setter 未在多个控件中绑定一个属性并返回时调用 [英] WPF UserControl: setter not called on binding one property in multiple controls and back
问题描述
我的 WPF UserControl 在多个控件中绑定一个属性并返回时遇到问题.不会调用业务对象的设置器.我现在搜索了几个小时并尝试了一些不起作用的东西.
I've got a problem with my WPF UserControl binding one property in multiple controls and back. The setters of the business object will not be called. I searched for hours now and tried serveral things which did not work.
我的代码
可以在这里下载:WpfApplicationUserControlProblem.zip
我的业务对象有 2 个要绑定的日期时间值.
My Business object has 2 DateTime Values to be bound.
public class BusinessObject
{
private DateTime _value1 = DateTime.Today.AddHours(10);
public DateTime Value1
{
get { return _value1; }
set { _value1 = value; } // will never be called but why??
}
private DateTime _value2 = DateTime.Today.AddDays(1).AddHours(15);
public DateTime Value2
{
get { return _value2; }
set { _value2 = value; } // will never be called but why??
}
}
我的主窗口有 2 个用户控件来绑定对象的 2 个值
My Main-Window has 2 user controls to bind the 2 values of my object
<Window x:Class="WpfApplicationUserControlProblem.MainWindow"
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:WpfApplicationUserControlProblem"
mc:Ignorable="d"
Title="MainWindow" Height="120.961" Width="274.489">
<Grid>
<local:DateTimeUserControl DateTimeValue="{Binding Value1, UpdateSourceTrigger=PropertyChanged}" Margin="10,10,0,0" VerticalAlignment="Top" HorizontalAlignment="Left" Width="241"/>
<local:DateTimeUserControl DateTimeValue="{Binding Value2, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Margin="10,39,0,0" VerticalAlignment="Top" Width="241"/>
</Grid>
public partial class MainWindow : Window
{
private BusinessObject _businessObject = new BusinessObject();
public MainWindow()
{
InitializeComponent();
DataContext = _businessObject;
}
}
我的 UserControl DateTimeUserControl 有一个 DependencyPropertyDateTimeValue",用于从主窗口接收绑定的业务值.使用DateTimeValuePropertyChangedCallback",我将接收到的值重定向到 DatePicker 的 DateValue 和 HourTextBox 的 HourValue.更改 DatePicker 或 HourTextBox 应该更新 DependencyPropertyDateTimeValue",因此也更新有界业务对象.那是我的计划.
My UserControl DateTimeUserControl has one DependencyProperty "DateTimeValue" for receiving the bound business value from the Main-Window. With the "DateTimeValuePropertyChangedCallback" I redirect the received value into a DateValue for the DatePicker and HourValue for the HourTextBox. Changing the DatePicker or HourTextBox should update the DependencyProperty "DateTimeValue" and therefore also the bounded business object. That was my plan.
<UserControl x:Class="WpfApplicationUserControlProblem.DateTimeUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WpfApplicationUserControlProblem"
x:Name="_this"
mc:Ignorable="d">
<Grid>
<DatePicker SelectedDate="{Binding Path=DateValue, ElementName=_this, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Margin="0,0,61,0"/>
<TextBox Text="{Binding Path=HourValue, ElementName=_this, UpdateSourceTrigger=PropertyChanged}" Height="24" VerticalAlignment="Top" HorizontalAlignment="Right" Width="56"/>
</Grid>
public partial class DateTimeUserControl : UserControl, INotifyPropertyChanged
{
public DateTimeUserControl()
{
InitializeComponent();
}
public event PropertyChangedEventHandler PropertyChanged;
public static readonly DependencyProperty DateTimeValueProperty = DependencyProperty.Register(nameof(DateTimeValue), typeof(DateTime), typeof(DateTimeUserControl), new PropertyMetadata(DateTimeValuePropertyChangedCallback));
public DateTime DateTimeValue
{
get { return (DateTime)GetValue(DateTimeValueProperty); }
set { SetValue(DateTimeValueProperty, value); }
}
private static void DateTimeValuePropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
DateTimeUserControl control = d as DateTimeUserControl;
control.FirePropertyChanged(d, new PropertyChangedEventArgs(nameof(DateValue)));
control.FirePropertyChanged(d, new PropertyChangedEventArgs(nameof(HourValue)));
}
private void FirePropertyChanged(object sender, PropertyChangedEventArgs args)
{
PropertyChanged?.Invoke(sender, args);
}
public DateTime DateValue
{
get { return DateTimeValue.Date; }
set { DateTimeValue = value.Date.AddHours(DateTimeValue.Hour); }
}
public string HourValue
{
get { return DateTimeValue.Hour.ToString(); }
set { DateTimeValue = DateTimeValue.Date.AddHours(int.Parse(value)); }
}
}
我不明白
除了在更新 DependencyProperty 时不调用业务对象的 setter 之外,一切似乎都正常.但为什么?我还尝试了 DependencyProperties 或 MultiBindingConverters 的所有方法.每次尝试都失败了.
Everything seems to work fine except that the setter of the business object is not called when the DependencyProperty is updated. But why? I also tried everything with DependencyProperties or MultiBindingConverters. I failed on every try.
有人可以帮忙吗?
推荐答案
DateTimeValue
绑定应该声明为 TwoWay
,而 UpdateSourceTrigger=PropertyChanged
肯定是多余的:
The DateTimeValue
Bindings should be declared as TwoWay
, while UpdateSourceTrigger=PropertyChanged
is certainly redundant:
<local:DateTimeUserControl DateTimeValue="{Binding Value1, Mode=TwoWay}" .../>
你也可以声明你的 DateTimeValue
依赖属性默认为双向绑定:
You could also declare your DateTimeValue
dependency property to bind two-way by default:
public static readonly DependencyProperty DateTimeValueProperty =
DependencyProperty.Register(
nameof(DateTimeValue),
typeof(DateTime),
typeof(DateTimeUserControl),
new FrameworkPropertyMetadata(
default(DateTime),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
DateTimeValuePropertyChangedCallback));
<小时>
您可能会问为什么这对于 UserControl 的 XAML 中的两个内部"绑定也不是必需的,但是 DatePicker.SelectedDate
和 TextBox.Text
属性已注册到 BindsTwoWayByDefault
.
You may ask why this isn't also necessary on the two "internal" bindings in the UserControl's XAML, but both the DatePicker.SelectedDate
and the TextBox.Text
property are already registered with BindsTwoWayByDefault
.
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