ListBox选择的项目事件 [英] ListBox selected items event

问题描述

亲爱的，

我有一个基于列表框选定项目事件的基本问题。

I have a basic question based on a listbox selected items event.

当用户选择列表框时items，我需要在MVVM属性中获取所选项目以执行某些验证。

When a user select a listbox items, I need to get the selected items in a MVVM property in order to perform some validation.

捕获此事件的最佳方法是将选定项目列表传递给我MVVM？

What is the best way to catch this event and pass it the list of slected items to my MVVM ?

问候

你的知识会被其他人提升。

Your knowledge is enhanced by that of others.

推荐答案

如果它只是一个选定的项目，那么你可以绑定到一个viewmodel属性并在setter中放入一些代码。

If it was just one selected item then you can bind to a viewmodel property and put some code in the setter for that.

如果你想要多个selecteditemS，那么它可能会更复杂。

If you want multiple selecteditemS then it's potentially rather more complicated.

假设您正在绑定ObservableCollection< RowVM>到ItemsSource。

Say you're binding ObservableCollection<RowVM> to ItemsSource.

在RowVM上你可以公开一个IsSelected并绑定它。

On RowVM you can expose an IsSelected and bind that.

实际上我在app中有一个基本的viewmodel类我是工作：

In fact I have a base viewmodel class in an app I'm working on:

    public class ListedItemViewModel : BaseValidViewModel
    {
        private bool isExpanded = false;

        public bool IsExpanded
        {
            get { return isExpanded; }
            set { isExpanded = value; RaisePropertyChanged(); }
        }
        private bool isSelected = false;

        public bool IsSelected
        {
            get { return isSelected; }
            set { isSelected = value; RaisePropertyChanged(); }
        }

通过样式应用的绑定：

  <Style TargetType="ListBoxItem">
       <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
       <Setter Property="Background" Value="Transparent"/>
       <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/>

这很简单，但不能很好地涵盖所有用例。

Which is pretty simple but doesn't cover all use cases so well.

如果您需要在父视图模型中执行其中一项更改，那么这有点复杂。

If you need to do something in the parent viewmodel when one of those changes then that's a bit of a complication.

您可以将引用传递给RowVM新手时的父母。它可能是视图的viewmodel，它创建了所有的RowVM。然后，您可以根据您想要的任何条件从RowVM调用父视图模型上的公共方法。

You could pass a reference into the RowVM for the parent when you new it up. It's probably the view's viewmodel which creates all your RowVM. You can then call a public method on the parent viewmodel from RowVM based on whatever criteria you want.

使用的另一种方法是附加属性/行为。添加附加属性意味着您可以绑定到该属性并且行为可以重复使用。

Another approach used is an attached property/ behaviour. Adding an attached property means you can then bind to that and a behaviour is re-usable.

这是一个实现：

http：// blog .functionalfun.net / 2009/02 / how-to-databind-to-selecteditems.html

http://blog.functionalfun.net/2009/02/how-to-databind-to-selecteditems.html

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