如何绑定到ViewModel中的列表框 [英] How to bind to a ListBox in a ViewModel

问题描述

这是交易:我必须从

Here's the deal: I have to take a SelectedItem from a Listbox, that I got from this question and add it to a ListBox in another UserControl. The ViewModels and models are all setup, I just need to know how to refer to the ListBox that is getting the items.

这将在ViewModel A下-通过接收项目的ListBox控制用户控件的ViewModel.

This would be under ViewModel A -- the ViewModel that controls the user control with the ListBox that receives the items.

//This is located in ViewModelA
private void buttonClick_Command()
{
    //ListBoxA.Items.Add(ViewModelB -> SelectedListItem);
}

我不明白如何获取ListBoxA.

I don't understand how to get ListBoxA.

会是strings的ObservableCollection吗?

为进一步说明:由ViewModelA控制的ListBoxA将在ViewModelB中从ListBoxB接收值.我在ViewModelA中包含了ViewModelB的属性

For further clarification: ListBoxA, controlled by ViewModelA will be receiving values from ListBoxB in ViewModelB. I have included a property for ViewModelB in ViewModelA

推荐答案

您需要在ViewModelA中拥有一个属性，该属性可以是实现IEnumerable的任何类型.我将使用一个列表:

You need to have a property in ViewModelA that can be any type that implements IEnumerable. I will use a list:

    public const string MyListPropertyName = "MyList";

    private List<string> _myList;

    /// <summary>
    /// Sets and gets the MyList property.
    /// Changes to that property's value raise the PropertyChanged event. 
    /// </summary>
    public List<string> MyList
    {
        get
        {
            return _myList;
        }

        set
        {
            if (_myList == value)
            {
                return;
            }

            RaisePropertyChanging(MyListPropertyName);
            _myList = value;
            RaisePropertyChanged(MyListPropertyName);
        }
    }

然后在列表框中，将ItemsSource设置为此列表

Then in your Listbox, you need to set the ItemsSource to this list

<ListBox ItemsSource="{Binding MyList}">
    .......
</ListBox>

现在，在构造器中，将要显示的数据填充到MyList中，然后在添加命令"中输入

Now in your constructer, fill MyList with the data you want to display, and on the Add Command, you want to put

MyList.Add(ViewModelB.myString);  

ViewModelB.myString假定从上一个问题开始，假设在ViewModelB中，您有一个属性myString绑定到ListBoxB的SelectedItem，并且您对ViewModelA中的ViewModelB实例具有引用.

ViewModelB.myString assuming from your previous question that in ViewModelB you have a property myString bound to the SelectedItem of ListBoxB, and you have a reference to the instance of ViewModelB in ViewModelA.

这应该做到，让我知道

更新:

您应该在VMA中使用ObservableCollection，因为该集合将添加到其中.

You should be using an ObservableCollection in VMA since the collection will be added to.

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