Bind to IDataErrorInfo
<Window
x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="WPF" Height="136" Width="260">
<Window.Resources>
<Style
x:Key="textBoxInErrorStyle"
TargetType="{x:Type TextBox}" >
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self},Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<DockPanel DockPanel.Dock="Right">
<AdornedElementPlaceholder/>
<Image Source="Error.png" Width="16" Height="16" ToolTip="{Binding Path=AdornedElement.ToolTip,
RelativeSource={RelativeSource
Mode=FindAncestor,
AncestorType={x:Type Adorner}}}"/>
</DockPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<StackPanel>
<TextBlock Text="First Name"/>
<TextBox Style="{StaticResource textBoxInErrorStyle}" Text="{Binding Path=FirstName, Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged,
ValidatesOnDataErrors=True}" />
<TextBlock Text="Age" Grid.Row="2" VerticalAlignment="Center"/>
<TextBox Style="{StaticResource textBoxInErrorStyle}"
Margin="4" Text="{Binding Path=Age, Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged,
ValidatesOnDataErrors=True}"/>
</StackPanel>
</Window>
//File:Window.xaml.cs
using System.Windows;
using System.ComponentModel;
namespace WpfApplication1
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
this.DataContext = new Employee(){FirstName = "A",Age = 26,};
}
}
public class Employee : INotifyPropertyChanged,IDataErrorInfo
{
private string firstName;
private int age;
public Employee()
{
FirstName = "A";
}
public string FirstName
{
get
{
return firstName;
}
set
{
if(firstName != value)
{
firstName = value;
OnPropertyChanged("FirstName");
}
}
}
public int Age
{
get
{
return age;
}
set
{
if(this.age != value)
{
this.age = value;
OnPropertyChanged("Age");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName){
if(this.PropertyChanged != null)
{
this.PropertyChanged(this,new PropertyChangedEventArgs(propertyName));
}
}
public string Error
{
get
{
return string.Empty;
}
}
public string this[string propertyName]
{
get
{
string message = string.Empty;
switch(propertyName)
{
case "FirstName":
if(string.IsNullOrEmpty(firstName))
message = "A person must have a first name.";
break;
case "Age":
if(age < 1)
message = "A person must have an age.";
break;
default:
break;
}
return message;
}
}
}
}
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