Question

I have entity class:

public class Project
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual string Description { get; set; }
}

this class implements IDataErrorInfo and INotifyPropertyChanged interfaces via Castle DynamicProxy interceptor. I have instance of this class in view model:

public class ProjectEditViewModel : Screen
{
    public Project Project { get; set; }

    ....
}

I am displaying this data in view:

<TextBox Grid.Row="0" Grid.Column="1" x:Name="Project_Name" Margin="4"/>
<TextBox Grid.Row="0" Grid.Column="2" x:Name="Project_Description" Margin="4"/>

INotifyPropertyChanged works well, but IDataErrorInfo not. It looks like IDataErrorInfo works only when it is implemented by viewmodel. Is there any simple way to have this validation on entity object instead of viewmodel?

Doing data validation by this aspect oriented programing makes the best sense to me so I would like to use it.

And if this is somehow connected with my problem, I am using this style to displaying validation errors:

<Style TargetType="{x:Type TextBox}">
  <Style.Triggers>
     <Trigger Property="Validation.HasError" Value="true">
        <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors).CurrentItem.ErrorContent}"/>
    </Trigger>
  </Style.Triggers>
</Style>

My understanding of XAML is really poor so sorry if I missed something what is obvious.

I asked this question also in CaliburnMicro discussion: http://caliburnmicro.codeplex.com/discussions/338196

Answer 1

If you are using Binding to bind the Text then set ValidatesOnDataErrors=True property of the Binding. Hope this will help.

<TextBox Grid.Row="0" Grid.Column="1" x:Name="Project_Name" Margin="4"
         Text="{Binding Project.Name, ValidatesOnDataErrors=True}" />