Question

我试图弄清楚是否有可能让DataTemplate触发器更新非ui属性中的值。它似乎不起作用。见下文。当您单击以显示Person对象时，实例会在复选框关闭时显示Valid属性。

人物对象：

    namespace WPFControls
{
    public class Person : INotifyPropertyChanged
    {
        public string Name { get; set; }

        private double _age = 0;
        public double Age
        {
            get { return _age; }
            set
            {
                if (_age != value)
                {
                    _age = value;
                    OnPropertyChanged(nameof(Age));
                }
                else
                {
                    Debug.WriteLine("NO CHANGE");
                }

            }
        }

        private bool valid = true;
        public bool IsValid {
            get { return valid; }
            set
            {
                if (valid != value)
                {
                    valid = value;
                    OnPropertyChanged(nameof(IsValid));
                }
                else
                {
                    Debug.WriteLine("isvalud no change");
                }
            }
        }

        public override string ToString()
        {
            return $"{nameof(Name)}: {Name}, {nameof(Age)}: {Age} valid: {nameof(IsValid)} {IsValid}";
        }

        public event PropertyChangedEventHandler PropertyChanged;

        [NotifyPropertyChangedInvocator]
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

XAML：

<Window x:Class="WPFControls.AgeForm"
        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:WPFControls"
        mc:Ignorable="d"
        Title="AgeForm" Height="300" Width="350">

    <Window.Resources>
        <DataTemplate DataType="{x:Type local:Person}">
            <Grid Margin="10,10,10,10">
                <Grid.RowDefinitions>
                    <RowDefinition Height="40"></RowDefinition>
                    <RowDefinition Height="40"></RowDefinition>
                    <RowDefinition Height="40"></RowDefinition>
                </Grid.RowDefinitions>

                <Grid.ColumnDefinitions>
                    <ColumnDefinition></ColumnDefinition>
                    <ColumnDefinition></ColumnDefinition>
                </Grid.ColumnDefinitions>

                <TextBlock Grid.Row="0" Grid.Column="0">Name:</TextBlock>
                <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Name, UpdateSourceTrigger=PropertyChanged}" Margin="8"/>

                <TextBlock Name="AgeText"  Grid.Row="1" Grid.Column="0">Age:</TextBlock>
                <TextBox Name="AgeBox" Grid.Row="1" Grid.Column="1" Text="{Binding Age, UpdateSourceTrigger=PropertyChanged}" Margin="8"/>

                <CheckBox Margin="50,0,0,0" Grid.Row="0" Grid.Column="0" Name="CheckBoxValid" IsChecked="{Binding IsValid, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" Content="IS VALID?"/>
            </Grid>

            <DataTemplate.Triggers>
                <DataTrigger Binding="{Binding Age}" Value="21">
                    <Setter TargetName="AgeText" Property="Background" Value="Red"/>
                    <Setter TargetName="CheckBoxValid" Property="CheckBox.IsChecked" Value="False"/>
                </DataTrigger>
            </DataTemplate.Triggers>
        </DataTemplate>

    </Window.Resources>


    <Grid Margin="20,20,20,20">

        <Grid.RowDefinitions>
            <RowDefinition Height="200"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <ContentControl Content="{Binding}"/>

        <StackPanel Grid.Row="1">
            <Button Name="ShowButton" Click="ShowButton_OnClick">_Show...</Button>
        </StackPanel>

    </Grid>
</Window>

请注意，Click事件只是MessageBox.Show（persion.ToString（））

Answer 1

Setter <Setter TargetName="CheckBoxValid" Property="CheckBox.IsChecked" Value="False"/>删除现有绑定，而Person属性未更新。所以我建议删除该setter并在视图模型中添加验证逻辑：

public double Age
{
    get { return _age; }
    set
    {
        if (_age != value)
        {
            _age = value;
            OnPropertyChanged(nameof(Age));
            if (_age == 21) IsValid = false;
        }
        else
        {
            Debug.WriteLine("NO CHANGE");
        }

    }
}

DataTemplate.Triggers绑定到非UI元素

1 个答案: