我有一个带有命令的 View 模型。但只有最后添加的项目可以通过该命令进行编辑。当你看颂歌时,这是有道理的。但这不是我想要的。我希望编辑所选项目。我将勾勒出我的问题:
我有一个模型,名为 部分
public class Part
{
private string _partcode;
private string _description;
public string PartCode
{
get { return _partcode.Trim(); }
set { _partcode = value; }
}
public string Description
{
get { return _description; }
set { _description = value; }
}
}
带有命令的 ViewModel,名为 零件 View 模型
/// <summary>
/// Returns a ViewModel containing all parts.
/// </summary>
/// <param name="dt">Database to use.</param>
public PartViewModel(DatabaseType dt)
{
GenerateViewModelForAllParts(dt);
}
private async void GenerateViewModelForAllParts(DatabaseType dt)
{
using (NexusWCFServiceClient client = new NexusWCFServiceClient())
foreach (Part item in await client.GetAllPartsAsync(dt))
{
_part = item;
_items.Add(item);
}
}
#endregion
#region Members
private ObservableCollection<Part> _items = new ObservableCollection<Part>();
private Part _part;
int count = 0;
#endregion
#region Properties
public ObservableCollection<Part> Items
{
get { return _items; }
set { _items = value; }
}
public Part Part
{
get { return _part; }
set { _part = value; }
}
public string PartCode
{
get { return Part.PartCode; }
set
{
if (Part.PartCode != value) /* Check if value is changed */
{
Part.PartCode = value;
RaisePropertyChanged("PartCode"); /* Raise event */
}
}
}
public string Description
{
get { return Part.Description; }
set
{
if (Part.Description != value)
{
Part.Description = value;
RaisePropertyChanged("Description");
}
}
}
#region Commands
private void UpdateDescriptionExecute()
{
//count++;
//Description = Description + count.ToString();
// Part.Description = "asdasdasd";
MessageBox.Show(PartCode);
}
private bool CanUpdateDescriptionExecute()
{
if (count >= 2)
return false;
else
return true;
}
public ICommand UpdateDescription
{
get
{
return new RelayCommand(UpdateDescriptionExecute, CanUpdateDescriptionExecute);
}
}
#endregion
}
现在,每当我尝试在 View 中触发命令时:
<Window x:Class="NexusWPF.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="700" Width="525" x:Name="TestView">
<Grid>
<StackPanel x:Name="stck">
<ListView x:Name="lb" ItemsSource="{Binding Items}">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical" x:Name="stck">
<TextBlock Text="{Binding Path=PartCode}"/>
<TextBlock Text="{Binding Path=Description}"/>
<Button Content="Update" DataContext="{Binding ElementName=TestView, Path=DataContext}" Command="{Binding UpdateDescription}" CommandParameter="{Binding}"/>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
</Grid>
</Window>
最后添加的项目(部件)被编辑。这是有道理的,因为 ViewModel 中有以下代码:
_part = item;
如何将命令绑定(bind)到所选项目。我想 viewmodel 一定有问题,而不是绑定(bind)。 _part get 每次添加新部件时都会被覆盖。但是我怎样才能改变它,让它起作用呢?
最佳答案
使用 RelayCommand<Part>
接受 Part
命令参数:
public ICommand UpdateDescription
{
get
{
return new RelayCommand<Part>(UpdateDescriptionExecute, CanUpdateDescriptionExecute);
}
}
private void UpdateDescriptionExecute(Part part)
{
MessageBox.Show(part.PartCode);
}
private bool CanUpdateDescriptionExecute(Part part)
{
if (count >= 2)
return false;
else
return true;
}
并稍微修改 Command 绑定(bind):
<Button Content="Update" Command="{Binding DataContext.UpdateDescription,ElementName=TestView}" CommandParameter="{Binding}"/>
关于c# - MVVM 命令选择最后添加的项目,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41853312/