在WPF MVVM +使用Command + CommandParameter在列表视图中删除一行

问题描述

我想删除使用Command和CommandParameter像下面的ListView控件中的一行。

 ＆LT; GridViewColumn标题=X＆GT;
＆LT; GridViewColumn.CellTemplate＆GT;
    ＆LT;＆DataTemplate的GT;
        ＆LT;＆StackPanel的GT;
           ＆LT; TextBlock的文本={结合CriteriaId}/＆GT;
           ＆LT;按钮名称=btnDeleteCriterion标签={结合CriteriaId}CONTENT ={结合CriteriaId}前景=红粗细=大胆
                                                             命令={结合DeleteCriterionCommand}
                                                                        的DataContext ={绑定的DataContext，的RelativeSource = {的RelativeSource FindAncestor，AncestorType =的ListView}}
                                                             CommandParameter ={绑定的RelativeSource = {自我的RelativeSource}，路径=标签}
                                                                        /＆GT;
        ＆LT;＆StackPanel的GT;
    ＆LT; / DataTemplate中＆GT;
＆LT; /GridViewColumn.CellTemplate>
 

我试图抓住按钮的Tag属性，并把它传递给命令像上面比像这样从列表中删除。

    public void DeleteCriterion(object criterionId)
    {
        int crtId = (int)criterionId;
        Criterion crt = _criteria.FirstOrDefault((c) => c.CriterionId == crtId);
        if (crt != null)
            _criteria.Remove(crt);
    }

but I always get criterionId parameter as null.

What am I doing wrong?

解决方案

Since you're explicitly setting the DataContext within the button, when you're doing a binding like {Binding SomeProperty} it will assume that SomeProperty is in the DataContext that you just set. Try using a more explicit binding like:

"{Binding RelativeSource={RelativeSource AncestorType=StackPanel}, Path=DataContext.CriteriaId}" 

which will give you the correct DataContext's CriteriaID like it is for the TextBlock.

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