我有以下XAML代码,用户在每次按下Enter键时都会提交内容。 EventToCommand
在ViewModel中调用AddFieldCommand
方法。
<TextBox x:Name="txtFields" Text="{Binding FieldsTextProperty, UpdateSourceTrigger=PropertyChanged}" Height="23" TextWrapping="NoWrap" Background="#FFCBEECD" AcceptsReturn="False" >
<i:Interaction.Triggers>
<iex:KeyTrigger Key="Enter">
<cmd:EventToCommand Command="{Binding DataContext.AddFieldCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" PassEventArgsToCommand="True"/>
</iex:KeyTrigger>
</i:Interaction.Triggers>
</TextBox>
在我的MainViewModel.cs中定义了
FieldsTextProperty
属性:public string FieldsTextProperty { get; set; }
我的
AddFieldCommand
的ICommand看起来像这样:public ICommand AddFieldCommand { get; private set; }
并像这样初始化:
AddFieldCommand = new RelayCommand<KeyEventArgs>(AddField);
方法AddField看起来像这样:
public void AddField(KeyEventArgs e)
{
FrameworkElement classDataVisualElement = (FrameworkElement)e.KeyboardDevice.Target;
ClassData classDataModel = (ClassData)classDataVisualElement.DataContext;
classDataModel.Fields.Add(FieldsTextProperty);
FieldsTextProperty = "";
RaisePropertyChanged("Fields");
}
该代码获取当前对象,并将文本框中的内容添加到该对象中。
这不起作用,我看不到为什么?
当我按下Enter键时,什么也没发生,而且
FieldsTextProperty
和AddField
从未被调用编辑:
我的“输出”窗口中出现以下错误:
'FieldsTextProperty' property not found on 'object' ''ClassData' (HashCode=46358046)'. BindingExpression:Path=FieldsTextProperty; DataItem='ClassData' (HashCode=46358046); target element is 'TextBox' (Name='txtFields'); target property is 'Text' (type 'String')
编辑2:
经过几次测试-看来问题出在
FieldsTextProperty
中。我的老 friend Console.Writeline(“AddField Method”)永远不会令人失望;)编辑3:
完整(几乎)的XAML代码:
<UserControl ..... >
<Grid>
<TextBlock Text="Class Name" Background="#FF96BB96" Foreground="Black" IsHitTestVisible="True">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseDown">
<cmd:EventToCommand Command="{Binding DataContext.MouseDownClassDataCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" PassEventArgsToCommand="True"/>
</i:EventTrigger>
<i:EventTrigger EventName="MouseMove">
<cmd:EventToCommand Command="{Binding DataContext.MouseMoveClassDataCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" PassEventArgsToCommand="True"/>
</i:EventTrigger>
<i:EventTrigger EventName="MouseUp">
<cmd:EventToCommand Command="{Binding DataContext.MouseUpClassDataCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" PassEventArgsToCommand="True"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBlock>
<StackPanel Opacity="{Binding DataContext.ModeOpacity, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}">
<Border BorderBrush="#FF53855E" BorderThickness="1" Height="25"/>
<!-- FIELDS ELEMENTS-->
<Grid>
<TextBox x:Name="txtFields" Text="{Binding FieldsTextProperty, UpdateSourceTrigger=PropertyChanged}" Height="23" TextWrapping="NoWrap" Background="#FFCBEECD" AcceptsReturn="False" >
<i:Interaction.Triggers>
<iex:KeyTrigger Key="Enter">
<cmd:EventToCommand Command="{Binding DataContext.AddFieldCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" PassEventArgsToCommand="True"/>
</iex:KeyTrigger>
</i:Interaction.Triggers>
</TextBox>
<TextBlock IsHitTestVisible="False" Text="Insert Fields.." VerticalAlignment="Center" HorizontalAlignment="Left" Margin="5,0,0,0" Foreground="DarkGray">
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding Text, ElementName=txtFields}" Value="">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</Grid>
<DataGrid x:Name="PropertiesControl1" Height="auto" ItemsSource="{Binding ClassDatas}" HeadersVisibility="None" AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="True">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding Fields}" Header="" Width="*" IsReadOnly="True"/>
</DataGrid.Columns>
</DataGrid>
<!-- More of the same code...-->
</StackPanel>
</Grid>
</UserControl>
最佳答案
我有一个预感..也许绑定(bind)发生时Command为null。
尝试 :
private ICommand _addFieldCommand;
public ICommand AddFieldCommand
{
get
{
if(_addFieldCommand == null)
_addFieldCommand = new RelayCommand<KeyEventArgs>(AddField);
return _addFieldCommand;
}
}
XAML:
<UserControl DataContext"={Binding Path=DataContext, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}">