How to implement the textbox will get back to the default value when textbox in lost focus ?
E.g
Any changes that has been done by user on textbox A, if he/she does not press the enter key and lost focus to another text box B. The textbox A value will change back to the default value.
If the user has press the enter key, the default value will be replaced by changes that has been done by user.
MainWindow XAML
<Window x:Class="TestValidationRule.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vr="clr-namespace:TestValidationRule"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:WPFBehaviorsSample="clr-namespace:TestValidationRule"
Title="MainWindow" Height="350" Width="525"><Window.Resources><Style x:Key="TextBoxErrorStyle" TargetType="TextBox"><Style.Triggers><Trigger Property="Validation.HasError" Value="True"><Setter Property="Foreground" Value="Red" /></Trigger></Style.Triggers></Style></Window.Resources><StackPanel Orientation="Horizontal"><TextBox x:Name="txtDiagPeriod" Width="150" Height="30" Validation.ErrorTemplate="{x:Null}" Style="{StaticResource TextBoxErrorStyle}"><TextBox.Text><Binding Path="DiagPeriod" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged"><Binding.ValidationRules><vr:DiagPeriodValidationRule x:Name="DiagPeriodValidation" /></Binding.ValidationRules></Binding></TextBox.Text><TextBox.InputBindings><KeyBinding Key="Enter" Command="{Binding WriteDiagPeriodCommand}" CommandParameter="{Binding ElementName=txtDiagPeriod, Path=(Validation.HasError)}"></KeyBinding></TextBox.InputBindings><!--<i:Interaction.Behaviors><WPFBehaviorsSample:ShowMessageOnLostFocusBehavior /></i:Interaction.Behaviors>--></TextBox><TextBox Width="150" Height="30" /></StackPanel></Window>
MainWindow View Model
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Input;
namespace TestValidationRule
{
public class MainWindowViewModel : INotifyPropertyChanged
{
private uint diagPeriod;
public uint DiagPeriod
{
get { return diagPeriod; }
set { diagPeriod = value; OnPropertyChanged("DiagPeriod"); }
}
private ICommand writeDiagPeriodCommand;
public ICommand WriteDiagPeriodCommand
{
get { return writeDiagPeriodCommand; }
set { writeDiagPeriodCommand = value; }
}
private uint defaultDiagPeriod = 100;
public MainWindowViewModel()
{
writeDiagPeriodCommand = new RelayCommand(ExecuteWriteDiagPeriodCommand);
//initial when first launch
diagPeriod = defaultDiagPeriod;
}
public void ExecuteWriteDiagPeriodCommand(object parameter)
{
var IsDiagPeriodHasError = (bool)parameter;
if (!IsDiagPeriodHasError && defaultDiagPeriod != diagPeriod)
{
defaultDiagPeriod = diagPeriod;
MessageBox.Show("Hello: " + defaultDiagPeriod);
}
else
{
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
}