1. ListBox MvvM
例子1. 简单的绑定，ItemsSource 绑定到一个实现了IEnumerable 的类上。一般该绑定都是双向的，所以优先考虑使用 ObservableCollection<T>
的类。这样界面和后台数据就同步了。针对于ListBox 的控件，我们比较关心的是SelectedItem，在mvvm 中，为了解耦前端界面和后台的逻辑，我们采用
如下的方式，SelectedItem 双向绑定到ViewModel上的一个公用属性上。同时，该公用属性要实现INotifyPropertyChanged 接口，例子如下：
XAML:
<ListBox Name="lst_catalog" ItemsSource="{Binding Catalogs}" SelectedItem="{Binding SelectedCatalog, Mode=TwoWay}">
</ListBox>
class:
public class ViewModel:InotifyPropertyChanged
{
public string SelectedCatalog
{
get
{
return _selectedCatalog;
}
set
{
_selectedCatalog = value;
UpdateItemSources();
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged()
{
if(PropertyChanged!=null)
{
PropertyChanged(this,new PropertyChangedEventArgs(""));
}
}
}
2. ListBox 中使用DisplayMemberPath 和Converter 来限制listBox 中显示的内容。例子如下：
xaml:
<ComboBox Margin="5,0" Grid.Column="2" SelectedItem="{Binding ParamValue.RoleOSTemplate, Mode=TwoWay, Converter={StaticResource SelectedOsConverter}}" >
<ComboBox.ItemsSource>
<MultiBinding Converter="{StaticResource OsFilter}">
<Binding RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}" Path="DataContext.OSList"/>
<Binding Path="ParamName"/>
</MultiBinding>
</ComboBox.ItemsSource>
</ComboBox>
class:
[selectedOSConverter]
public class TargetOSConvert : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
string osTemplate = value as string;
return GeneralInfoViewModel.SingleInstance.OSList.Where(each => each.OSName==osTemplate).FirstOrDefault();
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
OSMapping osm = value as OSMapping;
return osm.OSName;
}
}
[OSFilter]
public class OSListConvert:IMultiValueConverter
{
public object Convert(object[] value, Type targetType, object parameter, CultureInfo culture)
{
ObservableCollection<OSMapping> allList = (ObservableCollection<OSMapping>)value[0];
string roleName = (string)value[1];
if (roleName == null)
return null;
string osType = roleName.Contains("TSVDA") || roleName.Contains("DDC") || roleName.Contains("SF") ? "server" : "desktop";
ObservableCollection<OSMapping> returnVal = new ObservableCollection<OSMapping>( allList.Where(each => each.OSType==osType).ToList()) ;
return returnVal;
}
public object[] ConvertBack(object value,Type[] targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}