可单击按钮以获取数据 WPF MVVM

Question

View.Xaml

<Grid>
<ListView ItemsSource = "{Binding Path = dcCategory}" SelectedValuePath = "Key" SelectedValue = "{Binding Path = Category, Mode = TwoWay}">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel>
<StackPanel Orientation="Horizontal" >
<Button Content="Add Value" Command="{Binding Path=DataContext.AddValue, RelativeSource= {RelativeSource FindAncestor, AncestorType={x:Type ListView}}}"/>
<TextBlock Text="{Binding Path=Key.Name}"/>
</StackPanel>
<ListBox ItemsSource="{Binding Path=Value}" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
</ListView>
</Grid>

我的目标是单击"添加值"并发送所选项目(类别类型(。它现在正在工作，但不像我接受的那样。 为了只单击按钮，我必须单击第一个蓝色区域，然后用数据"捕获"类别"。否则，类别为空。

例

视图模型

private Category _Category;
public Category Category
{
get
{
return _Category;
}
set
{
if (_Category != value)
{
_Category = value;
OnPropertyChanged(() => Category);
}
}
}
public ICommand AddValue
{
get
{
if (_AddValue == null)
{
_AddValue = new BaseCommand(() => Messenger.Default.Send(CategoryValueCode.AddValue + "," + Category.CategoryId));
}
return _AddValue;
}
}

Answer 1

这是逻辑，因为按钮的命令将在设置ListView.SelectedValue之前执行。您可以更改它，如果您为Button处理PreviewMouseDown。我还发现最好将ListView.SelectionMode设置为Single.

<ListView ItemsSource = "{Binding Path = dcCategory}" SelectedValuePath = "Key" SelectedValue = "{Binding Path = Category, Mode = TwoWay}" SelectionMode="Single">
<Button Content="Add Value" Command="{Binding Path=DataContext.AddValue, RelativeSource= {RelativeSource FindAncestor, AncestorType={x:Type ListView}}}" PreviewMouseDown="PreviewMouseDown"/>

private void PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
ListViewItem lvi = null;
var visParent = VisualTreeHelper.GetParent(sender as FrameworkElement);
while (lvi == null && visParent != null)
{
lvi = visParent as ListViewItem;
visParent = VisualTreeHelper.GetParent(visParent);
}
if (lvi == null) { return; }
lvi.IsSelected = true;
}

Answer 2

• 我没有检查Rekshino解决方案

• 感谢您的提示，在此期间，在与问题作斗争的过程中，我进行了许多更改，完全改变了视图模型/视图。 我以这种方式实现了我的目标：

视图：

<Grid>
<ItemsControl ItemsSource = "{Binding listCategoryAddValue}" >
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel>
<StackPanel Orientation="Horizontal">
<Button Content="Add Value" Command="{Binding Path=AddValue}"/> 
<TextBlock Text="{Binding Category.Name}"/>
</StackPanel>
<ListBox ItemsSource="{Binding ValueList}" />
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal">
</StackPanel>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</Grid>

视图模型：

public class CategoriesViewModel : WszystkieViewModel<CategoryAddValue>
{
#region Fields & Properties
private ObservableCollection<CategoryAddValue> _listCategoryAddValue;
public ObservableCollection<CategoryAddValue> listCategoryAddValue
{
get
{
if (_listCategoryAddValue == null) { Load(); }
return _listCategoryAddValue;
}
set
{
if (_listCategoryAddValue != value)
{
_listCategoryAddValue = value;
OnPropertyChanged(() => listCategoryAddValue);
}
}
}
#endregion Fields & Properties
#region Constructor
public CategoriesViewModel() : base()
{
base.DisplayName = "Kategorie";
}
#endregion Constructor
#region Helpers
private void SendValue(int CategoryId)
{
Messenger.Default.Send(CategoryValueCode.AddValue + "," + CategoryId);
}
public override void Load()
{
var allCategories = (from k in db.Category select k).ToList();
_listCategoryAddValue = new ObservableCollection<CategoryAddValue>();
foreach (var i in allCategories)
{
_listCategoryAddValue.Add(new CategoryAddValue(new RelayCommand(() => SendValue(i.KategoriaId)))
{
Category = i,
ValueList = db.CategoryValue.Where(x => x.CategoryId== i.CategoryId).Select(x => x.Value).ToList()
});
}
}
#endregion Helpers
}

型

public class CategoryAddValue
{
public Category Category { get; set; }
public List<string> ValueList { get; set; }
private ICommand _addValue;
public ICommand AddValue
{
get
{
return _addValue;
}
}
public CategoryAddValue(RelayCommand command)
{
_addValue = command;
}
}