我需要什么才能进一步限定DataContext的绑定？

Question

我在这个问题中创建并将引用的文件是:

TechnicainSelectionView.xaml
TechnicianSelectionView.cs
TechnicianSelectionViewModel.cs
Technician.cs (Code First Entity)

我的TechnicanSelectionView.xaml中有以下xaml

<UserControl xmlns etc... here" 
             d:DesignHeight="48" d:DesignWidth="300">
    <Grid>
        <StackPanel>
            <Label Content="Select a Technican to run the test" FontWeight="Bold"></Label>
            <ComboBox ItemsSource="{Binding Technicians, Mode=TwoWay}"></ComboBox>
        </StackPanel>
    </Grid>
</UserControl>

ItemSource设置为绑定到的Technicians属性表示它 Cannot resolve Technicians due to an unknown DataContext.

因此,如果我们查看我的TechnicianSelectionView.cs代码隐藏...

public partial class TechnicianSelectionView : UserControl
{
    public TechnicianSelectionViewModel ViewModel { get; private set; }

    public TechnicianSelectionView()
    {
        InitializeComponent();

        Technician.GenerateSeedData();

        ViewModel = new TechnicianSelectionViewModel();
        DataContext = ViewModel;
    }
}

...我们看到我正在将视图的DataContext设置为我的TechnicianSelectionViewModel ...

public class TechnicianSelectionViewModel : ViewModelBase
{
    public ObservableCollection<Technician> Technicians { get; set; }

    public TechnicianSelectionViewModel()
    {
        Technicians = new ObservableCollection<Technician>();
    }

    public bool IsLoaded { get; private set; }

    public void LoadTechnicians()
    {
        List<Technician> technicians;

        using (var db = new TestContext())
        {
            var query = from tech in db.Technicians
                        select tech;

            foreach (var technician in query)
            {
                Technicians.Add(technician);
            }
        }

        IsLoaded = true;
    }
}

Techicians是我的ViewModel上的一个属性...

因此,为视图设置了DataContext,为什么它不能将ViewModel上的技术人员解析为它要绑定到的DataContext /属性？

编辑:

根据以下评论的关注点.这是设计时问题而不是编译时间.我应该在开始时说明这一点.

Answer 1

您需要在xaml中指定数据上下文的类型以获得设计时支持.即使您在代码隐藏中分配了数据上下文,设计人员也不会认识到这一点.

尝试在xaml中添加以下内容:

d:DataContext="{d:DesignInstance vm:TechnicianSelectionViewModel}"

有关详细信息,请参阅此链接.