如何将ListBox SelectedItem放入ViewModel类的实例中
本文关键字：实例 ViewModel 放入 ListBox SelectedItem | 更新日期: 2023-09-27 18:14:20
我的列表框的SelectedItem有一个问题。我想把选中的项放在HealthDiseaseViewModel的highlight属性中这是我的ViewModel:
public class HealthDiseaseViewModel : ObservableCollection<HealthDisease>
{
private string _feedBack;
HealthDiseaseDb _db = new HealthDiseaseDb();
public HealthDiseaseRetrieveSingleCommand RetrieveSingleCommand { get; set; }
public HealthDiseaseRetrieveManyCommand RetrieveManyCommand { get; set; }
public HealthDiseaseUpdateCommand UpdateCommand { get; set; }
public HealthDisease Entity { get; set; }
public HealthDisease Highlighted { get; set; }
public List<HealthDisease> EntityList { get; set; }
public HealthDiseaseViewModel()
{
RetrieveSingleCommand = new HealthDiseaseRetrieveSingleCommand(this);
RetrieveManyCommand = new HealthDiseaseRetrieveManyCommand(this);
UpdateCommand = new HealthDiseaseUpdateCommand(this);
Highlighted = new HealthDisease();
Entity = new HealthDisease();
RetrieveMany(Entity);
}
#region Methods
public void Retrieve(HealthDisease parameters)
{
Highlighted = _db.Retrieve(parameters);
}
public void RetrieveMany(HealthDisease parameters)
{
EntityList = new List<HealthDisease>();
EntityList = _db.RetrieveMany(parameters);
IList<HealthDisease> toBeRemoved = Items.ToList();
foreach (var item in toBeRemoved)
{
Remove(item);
}
foreach (var item in EntityList)
{
Add(item);
}
}
public void Insert(HealthDisease entity)
{
bool doesExist = false;
if (_db.Insert(entity, SessionHelper.CurrentUser.Id, ref doesExist))
{
_feedBack = "Item Successfully Saved!";
RetrieveMany(new HealthDisease());
}
else if (doesExist)
{
_feedBack = "Item Already Exists!";
}
else
{
_feedBack = "Not All Fields Were Filled-In!";
}
MessageBox.Show(_feedBack, "Item Insertion");
}
public void Update(HealthDisease entity)
{
bool doesExist = false;
if (_db.Update(entity, SessionHelper.CurrentUser.Id, ref doesExist))
{
_feedBack = "Item Successfully Updated!";
RetrieveMany(new HealthDisease());
}
else if (doesExist)
{
_feedBack = "Item Already Exists!";
}
else
{
_feedBack = "Not All Fields Were Filled-In!";
}
MessageBox.Show(_feedBack, "Item Edition");
}
public void Delete(HealthDisease entity)
{
var answer = MessageBox.Show(String.Format("Are you sure you want to delete 'n{0}?", entity.Name),
"Item Deletion", MessageBoxButtons.YesNo);
if (answer == DialogResult.No)
{
return;
}
if (_db.Delete(entity, SessionHelper.CurrentUser.Id))
{
_feedBack = "Item Successfully Deleted!";
RetrieveMany(new HealthDisease());
}
MessageBox.Show(_feedBack, "Item Deletion");
}
#endregion
}
我将我的ListBox的SelectedItem绑定为高亮，我希望它高亮。名称和高亮显示。Description到TextBlocks，但是TextBlocks不显示SelectedItem。我可以通过使用SelectedItem在这里做一个工作。名称和SelectedItem。描述，但问题是它会自动更新列表框，即使我没有点击保存按钮。使用对象高亮将解决这个问题，但我已经花了几个小时的挫折。这是我的加价。我省略了从ViewModel中绑定到UpdateCommand的SaveButton
<Grid Name="MainGrid" Background="Aqua" MinWidth="500" MinHeight="400"
DataContext="{Binding Source={StaticResource HealthViewModel}}">
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding Path=Highlighted.Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></TextBlock>
<ListBox x:Name="EntityListBox" Margin="10,0" Height="380"
ItemsSource="{Binding }"
DisplayMemberPath="Name"
SelectedItem="{Binding Path=Highlighted, Mode=TwoWay,
Converter={StaticResource ToHealthDiseaseConverter},
UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
</Grid>
我可以给你一个快速的答案，但有点希望你不要停在这里，试图找出为什么绑定到一个对象的属性不会工作。DependencyProperty绑定到实现INotifyPropertyChanged的实例，并正确引发PropertyChanged触发器。它不绑定到实例的"值"。看看你是否能弄清楚为什么绑定到高亮显示。名字不起作用。
我为你创建了一个简化的示例
<Window x:Class="WpfTestProj.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WpfTestProj"
mc:Ignorable="d"
d:DataContext="{d:DesignInstance Type=local:MainViewModel, IsDesignTimeCreatable=False}"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<local:MainViewModel/>
</Window.DataContext>
<Grid>
<StackPanel Orientation="Vertical">
<StackPanel>
<TextBlock Text="{Binding Path=HighlightedName}" />
</StackPanel>
<StackPanel>
<ListBox x:Name="EntityListBox" Margin="10,0"
ItemsSource="{Binding EntityList}"
DisplayMemberPath="Name"
SelectedItem="{Binding Path=Highlighted, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
</StackPanel>
</Grid>
public abstract class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public class HealthDisease
{
public string Name { get; set; }
}
public class MainViewModel : ViewModelBase
{
public ObservableCollection<HealthDisease> EntityList { get; set; }
public MainViewModel()
{
RetrieveMany();
}
private void RetrieveMany()
{
EntityList = new ObservableCollection<HealthDisease>
{
new HealthDisease {Name = "Disease A"},
new HealthDisease {Name = "Disease B"},
new HealthDisease {Name = "Disease C"}
};
}
private HealthDisease highlighted;
public HealthDisease Highlighted
{
get { return highlighted; }
set
{
highlighted = value;
OnPropertyChanged();
OnPropertyChanged("HighlightedName");
}
}
public string HighlightedName
{
get { return Highlighted == null ? string.Empty : Highlighted.Name; }
}
}