How to implement IDataErrorInfo on string indexers databinding?
With xaml (notice the binding on dictionary entry Attributes[Welcome]):
<Grid x:Name="LayoutRoot">
<StackPanel>
<TextBlock FontSize="36"
FontWeight="Bold"
Foreground="Purple"
Text="{Binding Attributes[Welcome]}"
VerticalAlignment="Center"
HorizontalAlignment="Center"
TextWrapping="Wrap" />
<TextBox Text="{Binding Attributes[Welcome],Mode=TwoWay, ValidatesOnDataErrors=True}"></TextBox>
<TextBox Text="{Binding Attributes[Welcome],Mode=TwoWay, ValidatesOnDataErrors=True}"></TextBox>
<TextBox Text="{Binding Test, Mode=TwoWay, ValidatesOnDataErrors=True}"></TextBox>
<TextBox Text="{Binding Test, Mode=TwoWay, ValidatesOnDataErrors=True}"></TextBox>
</StackPanel>
</Grid> When the view model implements IDataErrorInfo as:
public string Error
{
get { return ""; }
}
public string this[string columnName]
{
get {
return "Compulsory Error";
}
}
Only columnName == "Test" is ever passed. And therefore I get the following application:
How can I validate the values being set for the Attributes Dictionary?
I figured that I needed to implement IDataErrorInfo on the Dictionary rather than the viewmodel containing the dictionary. But since IDataErrorInfo member's conflict with IDicitonary. I ended up implementing INotifyDataErrorInfo.
Instead of using a Dictionary the more "MVVMish" way would be to create a simple ViewModel for the items you are going to display in your list. Then add them to a list (instead of a dictionary) and bind to those items. Then you can implement IDataErrorInfo on those ViewModels (along with any other custom logic or anything else you need).
链接地址: http://www.djcxy.com/p/44622.html上一篇: 如何绑定父级中的子级用户控件的数据上下文