Question

我有一个MVVM应用程序，其数据绑定DataGrid绑定到Resources<ResourceViewModel>。我在DataGrid通过

显示的资源数据中添加了一个额外的资源/行

private void OnResourceAddedToCollection(object sender, ResourceCollectionChangedEventArgs e)
{
    var viewModel = new ResourceViewModel(e.NewResource);
    Resources.Add(viewModel);
}

这很有效。但是，我采用完全相同的方法并尝试通过

将列添加到DataGrid

private void OnResourceCultureCollectionChanged(object sender, 
    ResourceCulturesCollectionChangedEventArgs e)
{
    Resources.Clear();
    foreach (var rvm in e.NewResourceCollection.Select(r => new ResourceViewModel(r)).ToList())
        Resources.Add(rvm);
}

其中事件参数包含更新的基础Resource。现在我检查了数据，它是正确的 - 正在添加列，但DataGrid没有显示新列。 我做错了什么？

Answer 1

添加列时需要重新绘制数据网格，重置DataGrid.ItemSource应该这样做。

查看：

public SomeView(IViewModel vm)
{
    ViewModel = vm;
    DataContext = ViewModel;

    InitializeComponent();

    ViewModel.PropertyChanged += (s, e) =>
    {
        switch (e.PropertyName)
        {
            case "IsResetingColumns":
                if (!ViewModel.IsResetingColumns)
                {
                    dataGrid.ItemsSource = null;
                    dataGrid.ItemsSource = ViewModel.Resources;
                }
                break;
            }
        };
    }

视图模型：

public class ViewModel : INotifyPropertyChanged
{
    private bool _isResetingColumns;

    public bool IsResetingColumns
    {
        get
        {
            return _isResetingColumns;
        }
        set
        {
            if (_isResetingColumns == value)
                return;
            _isResetingColumns = value;
            OnPropertyChanged("IsResetingColumns");
        }
    }

    private void OnResourceCultureCollectionChanged(object sender,
                                                    ResourceCulturesCollectionChangedEventArgs e)
    {
        //VIEWMODEL IS SETTING THIS TO TRUE BEFORE RESETTING `RESOURCES`
        IsResetingColumns = true;

        Resources.Clear();
        foreach (var rvm in e.NewResourceCollection.Select(r => new ResourceViewModel(r)).ToList())
            Resources.Add(rvm);

        //VIEW'S LISTENING TO THIS PROPERTY CHANGED (naming could be better, or an event ,but the gist is there)
        IsResetingColumns = false;
    }

DataGrid更新已添加的行但不适用于已添加的列

1 个答案: