未使用DataTemplate DataType绑定属性 [英] Property not binded using DataTemplate DataType

问题描述

我有一个主要的视图模型，可以创建许多子视图模型

I have a main viewmodel which create many child viewmodel

通过以下方式定义子vm数据模板:

The child vm datatemplate is definied in the following way:

<DataTemplate DataType="{x:Type vm:ChildVM}">
    <view:childview />
</DataTemplate>

子视图具有以下代码:

	<TextBox>
		<i:Interaction.Behaviors>
			<behavior:AppendTextBehavior AppendTextAction="{Binding AppendTextAction, Mode=OneWayToSource}" />
		</i:Interaction.Behaviors>
	</TextBox>

行为类:

public class AppendTextBehavior : Behavior<TextBox>
{
    public Action<string> AppendTextAction
    {
        get { return (Action<string>)GetValue(AppendTextActionProperty); }
        set { SetValue(AppendTextActionProperty, value); }
    }

    public static readonly DependencyProperty AppendTextActionProperty =
        DependencyProperty.Register("AppendTextAction", typeof(Action<string>), typeof(AppendTextBehavior));

    protected override void OnAttached()
    {
        base.OnAttached();
        SetCurrentValue(AppendTextActionProperty, (Action<string>)AssociatedObject.AppendText);
        AssociatedObject.TextChanged += AssociatedObject_TextChanged;
    }

    void AssociatedObject_TextChanged(object sender, EventArgs e)
    {
        // does something
    }
}

ChildVM:

ChildVM :

	private Action<string> appendTextAction;

	public Action<string> AppendTextAction
	{
		get { return appendTextAction; }
		set {
			appendTextAction = value;
			RaisePropertyChanged(() => AppendTextAction);
		}
	}

推荐答案

F加星标，

Hi F Starred,

>>显然，上面的代码是错误的，因为我不需要再次创建子视图模型.我该怎么做才能使AppendTextAction绑定起作用?

根据您的描述，我认为这可能是您的OnAttached()事件中的一些错误.您可以尝试更改代码.

From your description, I think, it is maybe some errors in your OnAttached() event. You can try to change the code.

    protected override void OnAttached()
        {
            //set AppendTextAction values 
               AppendTextAction = (Action<string>)AssociatedObject.AppendText;

            AssociatedObject.TextChanged += (sender, a) =>
            {
                if (!IsFocused)
                {
                    AssociatedObject.Focus();
                    AssociatedObject.Select(AssociatedObject.Text.Length, 0);
                }
            };
            base.OnAttached();
        }

以下文章供您参考.希望对您有帮助.

The following article for your reference. I hope it will helpful for you.

WPF中的附加行为:
http://www.mindscapehq.com/blog/index .php/2009/02/01/attached-behaviours-in-wpf/

Attached behaviours in WPF:
http://www.mindscapehq.com/blog/index.php/2009/02/01/attached-behaviours-in-wpf/

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最好的问候，

吕汉楠

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