WPF CommandParameter MultiBinding值空 [英] WPF CommandParameter MultiBinding values null

问题描述

我只是想结合两个控件命令参数，并将它们传递到我的命令作为 [对象] 。

I am simply trying to bind two controls as command parameters and pass them into my command as an object[].

XAML：

<UserControl.Resources>
        <C:MultiValueConverter x:Key="MultiParamConverter"></C:MultiValueConverter>
    </UserControl.Resources>

    <StackPanel Orientation="Vertical">
        <StackPanel Orientation="Horizontal">
            <Button Name="Expander" Content="+" Width="25" Margin="4,0,4,0" Command="{Binding ExpanderCommand}">
                <Button.CommandParameter>
                    <MultiBinding Converter="{StaticResource MultiParamConverter}">
                        <Binding ElementName="Content"/>
                        <Binding ElementName="Expander"/>
                    </MultiBinding>
                </Button.CommandParameter>
            </Button>
            <Label FontWeight="Bold">GENERAL INFORMATION</Label>
        </StackPanel>
        <StackPanel Name="Content" Orientation="Vertical" Visibility="Collapsed">
            <Label>Test</Label>
        </StackPanel>
    </StackPanel>

命令：

public ICommand ExpanderCommand
        {
            get
            {
                return new RelayCommand(delegate(object param)
                    {
                        var args = (object[])param;
                        var content = (UIElement)args[0];
                        var button = (Button)args[1];
                        content.Visibility = (content.Visibility == Visibility.Visible) ? Visibility.Collapsed : Visibility.Visible;
                        button.Content = (content.Visibility == Visibility.Visible) ? "-" : "+";
                    });
            }
        }

转换：

public class MultiValueConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return values;
        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException("No two way conversion, one way binding only.");
        }
    }

基本上正在发生的事情是，结合似乎是工作的罚款，该转换器返回一个 [对象] 包含正确的价值观，但是，当命令执行参数是[] 包含元素相同数量的的对象，除非它们是空。

Basically what is happening is that the binding seems to be working fine and the converter is returning an object[] containing the correct values, however when the command executes the param is an object[] containing the same number of elements except they are null.

有人能告诉我，为什么 [对象] 参数被设置为值空？

Can someone please tell me why the values of the object[] parameter are being set to null?

谢谢， 亚历克斯。

推荐答案

这会做到这一点：

public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
    return values.ToArray();
}

看看这个<一href="http://stackoverflow.com/questions/10759523/using-imultivalueconverter-to-pass-multiple-commandparameters-to-viewmodel">question为解释

这篇关于WPF CommandParameter MultiBinding值空的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！