(MVVM-light) style.triggers不工作

Question

我正在使用mvvm-light库做WPF(MVVM)项目，遇到了这样的问题:我想创建依赖于我的ModelView的值的样式触发器，但它不起作用

XAML部件：

<Window...

<Window.DataContext>
        <!-- Declaratively create an instance of our Alarm View Model-->
        <local:AlarmView />
</Window.DataContext>
....

<Grid>
<Grid.RowDefinitions>
            <RowDefinition Height="30" />
            <RowDefinition Height="100" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
                    <ColumnDefinition Width="100" />
                    <ColumnDefinition Width="100" />
                    <ColumnDefinition Width="100" />
</Grid.ColumnDefinitions>
<Button Grid.Row="0" Command="{Binding ChangeLocation}" Content="Click"></Button>    
<ListView 
         Grid.Row="1"
         Name="LV1" 
         ItemsSource="{Binding Items}"
         >
<ListView.Style>
            <Style TargetType="{x:Type ListView}">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Location}" Value="0">
                        <Setter Property="Grid.ColumnSpan" Value="3"></Setter>
                    </DataTrigger>
                    <DataTrigger Binding="{Binding Location}" Value="1">
                        <Setter Property="Grid.ColumnSpan" Value="1"></Setter>
                    </DataTrigger>
                    <DataTrigger Binding="{Binding Location}" Value="2">
                        <Setter  Property="Grid.ColumnSpan" Value="2"></Setter>
                    </DataTrigger>
                    <DataTrigger Binding="{Binding Location}" Value="3">
                        <Setter Property="Grid.ColumnSpan" Value="3"></Setter>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </ListView.Style>    
 </ListView>
 </Grid>
 </Window>

来自ModelView的部分

class AlarmView : ViewModelBase
{
...
int _location = 0;
...
public int Location 
    {
        get { return _location; }
        set 
        {
            _location = value;
            RaisePropertyChanged("Location");
        }
    }    
...
public RelayCommand ChangeLocation { get; set; }
...
ChangeLocation = new RelayCommand(() => 
        {
            if (Location < 3)
            {
                Location++;
            }
            else Location = 0;
        });
...

这看起来没问题，但是当我改变位置时什么也不会发生。为了检查我的命令，我将它绑定到TextBox - all works。哪里会有问题呢？

Answer 1

你有没有试过在你的绑定上使用UpdateSourceTrigger=PropertyChanged？我也遇到了类似的问题，这也解决了我的问题。

<DataTrigger Binding="{Binding Location, UpdateSourceTrigger=PropertyChanged}" Value="0">
     <Setter Property="Grid.ColumnSpan" Value="3"></Setter>
</DataTrigger>