第一:我是MVVM和WPF的新手。Wpf MVVM - 选项卡式界面不能按预期工作
我想用选项卡式用户界面创建一个小应用程序。用户可以使用应打开新TabItem的按钮来创建产品和存储位置。
我的视图代码如下所示:
<TabControl ItemsSource="{Binding Workspaces}"
IsSynchronizedWithCurrentItem="True"
Margin="3"
DockPanel.Dock="Top">
<TabControl.ItemTemplate>
<DataTemplate>
<Label Content="{Binding DisplayName}" />
</DataTemplate>
</TabControl.ItemTemplate>
</TabControl>
和视图模型是这样的:
ObservableCollection<WorkspaceViewModel> _workspaces;
public ObservableCollection<WorkspaceViewModel> Workspaces
{
get
{
if (_workspaces == null)
{
_workspaces = new ObservableCollection<WorkspaceViewModel>();
}
return _workspaces;
}
set
{
_workspaces = value;
}
}
public void AddProduct(object obj)
{
Workspaces.Add(new ProductViewModel());
}
其他各种按钮添加不同的ViewModels到工作区集合。
我已经定义了多个数据模板(每个ViewModel一个)。这里是一个:
<DataTemplate DataType="{x:Type vm:ProductViewModel}">
<vw:ProductView />
</DataTemplate>
的WorkspaceViewModel是这样的:
namespace Inventory.Desktop.ViewModels
{
public abstract class WorkspaceViewModel : INotifyPropertyChanged
{
#region Events and EventHandlers
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
}
和例如ProductViewModel
namespace Inventory.Desktop.ViewModels
{
public class ProductViewModel: WorkspaceViewModel
{
private Product _product;
private string _displayName;
public string DisplayName
{
get
{
if (String.IsNullOrEmpty(_displayName))
{
return "Neues Produkt";
} else
{
return _displayName;
}
}
set
{
_displayName = value;
NotifyPropertyChanged("DisplayName");
}
}
#region Public Properties
public Product Product
{
get
{
return _product;
}
set
{
_product = value;
NotifyPropertyChanged("Product");
}
}
public string Title
{
get
{
return _product.Title;
}
set
{
_product.Title = value;
NotifyPropertyChanged("Title");
}
}
public string ScanCode
{
get
{
return _product.ScanCode;
}
set
{
_product.ScanCode = value;
NotifyPropertyChanged("ScanCode");
}
}
public string Manufacturer
{
get
{
return _product.Manufacturer;
}
set
{
_product.Manufacturer = value;
NotifyPropertyChanged("Manufacturer");
}
}
public string ManufacturerNumber
{
get
{
return _product.ManufacturerNumber;
}
set
{
_product.ManufacturerNumber = value;
NotifyPropertyChanged("ManufacturerNumber");
}
}
public string Description
{
get
{
return _product.Description;
}
set
{
_product.Description = value;
NotifyPropertyChanged("Description");
}
}
#endregion
#region Commands
private ICommand _saveCommand;
public ICommand SaveCommand
{
get
{
return _saveCommand;
}
set
{
_saveCommand = value;
}
}
#endregion
#region Command Executions
public void Save(object obj)
{
using (var db = new InvContext())
{
db.Products.Attach(Product);
db.Entry(Product).State = Product.ProductId == 0 ?
EntityState.Added : EntityState.Modified;
db.SaveChanges();
}
MessageBox.Show("Product saved: " + Product.Title);
}
#endregion
#region Constructors
public ProductViewModel()
{
if (_product == null)
{
_product = new Product();
}
SaveCommand = new RelayCommand(new Action<object>(Save));
}
#endregion
}
}
这里ProductView.xaml
观点:
<UserControl x:Class="Inventory.Desktop.Views.ProductView"
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"
mc:Ignorable="d"
d:DesignHeight="400" d:DesignWidth="450">
<DockPanel>
<StackPanel DockPanel.Dock="Top" Orientation="Horizontal" FlowDirection="RightToLeft">
<Button Name="SaveProductButton" Command="{Binding SaveCommand}" Content="Speichern" Margin="3" BorderThickness="0">
</Button>
</StackPanel>
<StackPanel DockPanel.Dock="Top" VerticalAlignment="Stretch">
<Label Content="Scan Code" />
<TextBox Text="{Binding Path=ScanCode}" HorizontalAlignment="Stretch" Margin="3" Padding="3" Height="50" TextAlignment="Right">
<TextBox.Background>
<ImageBrush ImageSource="..\Images\Barcode32.png" AlignmentX="Left" Stretch="None" />
</TextBox.Background>
</TextBox>
<Label Content="Bezeichnung" />
<TextBox Text="{Binding Path=Title, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
<Label Content="Hersteller" />
<TextBox Text="{Binding Path=Manufacturer, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
<Label Content="Hersteller Nummer" />
<TextBox Text="{Binding Path=ManufacturerNumber, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
<Label Content="Beschreibung/Information" />
<TextBox Text="{Binding Path=Description, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
</StackPanel>
</DockPanel>
</UserControl>
和这里的代码-beh IND ProductView.xaml.cs
:
namespace Inventory.Desktop.Views
{
/// <summary>
/// Interaktionslogik für ProductView.xaml
/// </summary>
public partial class ProductView : UserControl
{
ProductViewModel _productModel = new ProductViewModel();
public ProductView()
{
InitializeComponent();
base.DataContext = _productModel;
}
}
}
什么是目前的工作:
- 当我点击一个按钮,我得到了一个新的TabItem显示正确的观点和所有的命令正常工作。
什么是不工作:
当我打开的TabItem,输入一些信息,然后我打开一个不同的视图模型的另一个的TabItem,切换焦点到新的TabItem,然后回原来的oen,那么所有输入的信息都消失了(对象为null)。
当我打开一个TabItem,输入一些信息,然后用相同的ViewModel打开另一个TabItem,然后两个TabItems显示相同的信息。
当我添加一个新的TabItem时,它不会得到焦点。
我完全失去了,我希望你能告诉我我做错了什么。
最佳
斯特凡
好像问题出在你的WorkspaceViewModel,你能发布一些资讯? –
Hi Mujahid。我编辑我的问题,并包括模型 – Stefan
尝试使用UpdateSourceTrigger = PropertyChanged在您的问题的文本框 –