在XAML中为集合项设置转换器的位置 [英] Where to set the Converter for items of a collection in XAML

问题描述

我刚刚使我的第一个转换器从int转换为string。我有一个用整数（年）填充的组合框，但是如果值是0，我希望组合框显示'All'。

I just made my first converter to convert from int to string. I have a combobox fill with integers(years) but if the value is 0 I want the combobox to show 'All'.

这是我的转换器：

public class IntToString : IValueConverter
{
     public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value != null)
            {
                int intY = (int)value;

                if (intY == 0)
                {
                    String strY = "All";
                    return strY;
                }
                else
                {
                    return intY.ToString();
                }
            }

            return String.Empty;
        }

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

        }
    }

在XAML中，应该在哪里设置转换器？我在组合框的ItemsSource中尝试过：

In XAML where should I set the converter ? I tried in the ItemsSource of the combobox:

ItemsSource="{Binding YearsCollection, Converter={StaticResource intToStringYearConverter}}"

但是我总是在这行得到 InvalidcastException ：

But I always get InvalidcastException on this line:

int intY = (int)value;

推荐答案

问题是您正在尝试转换整个

The problem is that you are trying to convert the entire collection rather than just one item from the collection.

您可能想执行以下操作：

You would want to do something like this:

<ListBox ItemsSource="{Binding YearsCollection}">
    <ListBox.ItemTemplate>
        <DataTemplate>
             <Border DataContext="{Binding Converter={StaticResource intToStringYearConverter}">
             ...
             </Border>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

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