将 ViewModel 绑定到 ComboBox 时遇到问题 [英] Having trouble binding ViewModel to ComboBox

问题描述

我的视图模型设置如下

public class cDriveListVM
{
    public string Drive { get; set; }
    public cDriveListVM(string name)
    {
        Drive = name;
    }
}

我在窗口中声明了 observablecollection 并将其 datacontext 设置为这个 observable 集合.

I declare the observablecollection in the window and set its datacontext to this observable collection.

public ObservableCollection<cDriveListVM> DriveList { get; set; }
private void dl()
{
    DriveList = new ObservableCollection<cDriveListVM>();
    DriveList.Add(new cDriveListVM("drive 1"));
    DriveList.Add(new cDriveListVM("drive 2"));
    this.DataContext = DriveList;
}

组合框的 Xml:

<ComboBox x:Name="Drive_ComboBox" ItemsSource="{Binding Path=Drive}" HorizontalAlignment="Center" IsReadOnly="True" Grid.Column="0" Grid.Row="0" Width="300" Margin="10" SelectionChanged="Drive_Changed" Height="22" VerticalAlignment="Top"/>

我只是在学习如何使用 Viewmodel，所以我不确定我做错了什么，任何帮助将不胜感激.我更新了 xml 文件，结果是以下组合框.

I am just learning how to use Viewmodel so I am unsure what I am doing wrong, any help would be appreciated. I updated the xml file it results in the following combbox.

推荐答案

这段代码存在一些问题.

There are a few problems with this code.

一、绑定设置错误.由于 viewmodel 集合的属性是 DriveList，所以绑定应该是 ItemsSource="{Binding Path=DriveList}".

One, the binding is set up wrong. Since the property with the viewmodel collection is DriveList, the binding should be ItemsSource="{Binding Path=DriveList}".

二，您试图从您的视图模型中显示一个字段，这是不可行的.WPF 的绑定引擎只对属性起作用，所以视图模型应该有一个属性:

Two, you are attempting to display a field from your viewmodel, which is not doable. WPF's binding engine only works with properties, so the viewmodel should have a property:

public string Drive { get; set; }

最后，DisplayMemberPath 应与视图模型中的属性名称匹配:DisplayMemberPath="Drive".

And finally, the DisplayMemberPath should match the property name from the viewmodel: DisplayMemberPath="Drive".

更新:我刚刚注意到 DataContext 本身就是可观察的集合——我可能在第一次阅读时错过了它.在这种情况下，您希望直接绑定到数据上下文:

Update: I just noticed that the DataContext is the observable collection itself -- I probably missed it on the first read. In that case, you want to bind directly to the data context:

ItemsSource="{Binding}"

并将 DisplayMemberPath 设置为要显示的属性:

And set DisplayMemberPath to the property you want to display:

DisplayMemberPath="Drive"

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