WPF.对于多触发条件，“属性"必须具有非空值 [英] WPF. Must have non-null value for 'Property' for multitrigger condition

问题描述

有多重触发，条件之一不为空，所以如果 StowedAssetDetailedThumbnailViewModel != null 则设置模板

Have multitrigger, one of the conditions is not null, so if StowedAssetDetailedThumbnailViewModel != null then set template

<Style.Triggers>
    <MultiTrigger>
        <MultiTrigger.Conditions>
            <Condition Property="IsSelected" Value="true" />
            <Condition Binding="{Binding Path=StowedAssetDetailedThumbnailViewModel,
                                         Converter={StaticResource isNull}}"
                       Value="False"/>
        </MultiTrigger.Conditions>
        <Setter Property="Template" Value="{StaticResource SelectedTemplate}" />
    </MultiTrigger>
</Style.Triggers>

使用简单的转换器:

return isNull == null;

错误是属性必须具有非空值

更新:谢谢，最终的解决方案是

UPDATE: Thanks, the final solution is

<Style.Triggers>
    <MultiDataTrigger>
        <MultiDataTrigger.Conditions>
            <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}"
                       Value="true" />
            <Condition Binding="{Binding Path=StowedAssetDetailedThumbnailViewModel,
                                 Converter={StaticResource isNull}}"
                                 Value="false"/>
        </MultiDataTrigger.Conditions>

        <Setter Property="Template" Value="{StaticResource SelectedTemplate}" />
    </MultiDataTrigger>
</Style.Triggers>

推荐答案

在这种情况下，您需要使用 MultiDataTrigger.MultiTrigger 只能由依赖属性触发.

You'll want to use a MultiDataTrigger in this case. A MultiTrigger can only be triggered by dependency properties.

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