Question

我遇到了转换器的问题......一旦绑定集合被更新，它们就不会触发，尽管它们在首次填充集合时会触发。我想在收集时发生变化时让他们开火。

到目前为止，我已经构建了一个简单的转换器：

public class TableConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {

        VM.Measurement t = ((VM.Measurement)((TextBlock)value).DataContext);
        if (t.Delta != null)
        {
            if (Math.Abs((double)t.Delta) < t.Tol)
                return "Green";
            else
                return "Red";
        }
        else
            return "Red";
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

链接到样式

<conv:TableConverter x:Key="styleConvStr"/>

<Style x:Key="CellStyleSelectorTol" TargetType="syncfusion:GridCell">
    <Setter Property="Background" Value="{Binding   RelativeSource={RelativeSource Self}, Path=Content, Converter={StaticResource styleConvStr}}" />
</Style>

在此DataGrid中使用了

 <syncfusion:SfDataGrid x:Name="CheckGrid" BorderBrush="White" Grid.Row="1" Grid.Column="1" AllowEditing="True"  ItemsSource="{Binding ChecksList, Mode=TwoWay}"  Background="White"   SnapsToDevicePixels="False"
                            ColumnSizer="None"  AllowResizingColumns="False" AllowTriStateSorting="True" AllowDraggingColumns="False" CurrentCellEndEdit="CheckGrid_CurrentCellEndEdit" AutoGenerateColumns="False"
                            NavigationMode="Cell" HeaderRowHeight="30" RowHeight="21"   GridPasteOption="None" Margin="20 10 10 10" AllowGrouping="True" SelectedItem="{Binding SelectedLine, Mode=TwoWay}"
                           SelectionUnit="Row"  SelectionMode="Single" RowSelectionBrush="#CBACCB"  VirtualizingPanel.IsVirtualizing="True"  Visibility="Visible">

                                <syncfusion:GridTextColumn Width="100" ColumnSizer="SizeToCells" AllowEditing="True"  MappingName="Measured" CellStyle="{StaticResource CellStyleSelectorTol}" HeaderText="Measured" TextAlignment="Center"   AllowFiltering="False" FilterBehavior="StringTyped"/>

VM包含一个Observable Collection，它一直实现NotifyPropertyChanged到Measurement Class。这些属性很好地启动，因此它不是一个具有约束力的问题。

 private ObservableCollection<Measurement> _checkList = new ObservableCollection<Measurement>();
    public ObservableCollection<Measurement> ChecksList
    {
        get
        {
            return _checkList;
        }
        set
        {
            _checkList = value;
            NotifyPropertyChanged();
        }
    }

对此的任何帮助将不胜感激。

谢谢

编辑：这是更新集合的代码。抱歉它很乱。 Lineitem是更新Measured和Delta的选定行。一旦修改，它们就会正确显示在网格中。

public void NewMeasurement(VM.Measurement measurementShell)
{
    using (VMEntity DB = new VMEntity())
    {
        var Check = CheckSets.Where(x => x.ID == SelectedLine.ID).First();
        if (Check.Measurement == null)
        {
            Check.Measurement = measurementShell.Index;
            var Lineitem = ChecksList.Where(x => x.ID == SelectedLine.ID).First();
            var measurement = DB.Measurements.Where(x => x.Index == Check.Measurement).First();
            Lineitem.Measured = (double)measurement.measurement1;
            Lineitem.Delta = Lineitem.Measured - Lineitem.Target;

Answer 1

好的，问题是你在LineItem方法中更改了的单元格内容项NewMeasurement()，但它仍然是相同的对象，因此单元格的内容不会改变。单元格的Content是绑定的来源。如果不改变，绑定将不会唤醒并更新目标。你正在提升PropertyChanged，但是这个特殊的绑定无法让你知道它希望它这些属性更改的对象。足够简单的修复：我们将开始准确地告诉它要听什么。

幸运的是，解决方案意味着简化了一些代码。将UI控件传递给值转换器是很奇特的，不是必需的。

转换器中您关注的是Measurement.Delta和Measurement.Tol。当任何一个发生变化时，Binding应该更新其目标。你不想以聪明的方式做到这一点。你只想要每个Binding。那是Binding的工作。

告诉Binding您关心这些属性，并重写转换器以接受它们作为参数。

<Style x:Key="CellStyleSelectorTol" TargetType="syncfusion:GridCell">
    <Setter 
        Property="Background" 
        >
        <Setter.Value>
            <MultiBinding Converter="{StaticResource styleConvStr}">
                <Binding Path="Delta" />
                <Binding Path="Tol" />
            </MultiBinding>
        </Setter.Value>
    </Setter>
</Style>

转换器：

public class TableConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        //  I'm inferring that Measurement.Delta is Nullable<double>; if that's 
        //  not the case, change accordingly. Is it Object instead? 
        double? delta = (double?)values[0];
        double tol = (double)values[1];

        if (delta.HasValue && Math.Abs(delta.Value) < tol)
        {
            return "Green";
        }
        return "Red";
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

收集更新后转换器未触发

1 个答案: