wpf - validation - how to show tooltips and disable "run" button - wpf

Question

Hi
I need to validate some of textboxes in my application. I decied to use validation rule
"DataErrorValidationRule". That's why in my class I implemented IDataErrorInfo interface and wrote aproperiate functions. In my xaml code I added bindings and validation rules to textboxes
<TextBox x:Name="txtName" Grid.Column="3" Grid.Row="1" TextAlignment="Center" >
<TextBox.Text>
<Binding Path="Name" >
<Binding.ValidationRules>
<DataErrorValidationRule></DataErrorValidationRule>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
Validation of this textbox is OK - I mean red frame appears on textbox if data is wrong. However what I need to do is to show tooltip on that textbox, but what is more important I have to disable button "Run" if any textboxes have wrong data. What is the best way to do taht ??
EDIT
First problem was solved, but I have an another. I need to use MultiBindings to validate my Button. So I did sth like that
<Button x:Name="btnArrange" Grid.Column="0" Content="Rozmieść" Click="btnArrange_Click" >
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Value="False">
<DataTrigger.Binding>
<MultiBinding Converter="{StaticResource BindingConverter}">
<Binding ElementName="txtName" Path="Validation.HasError" />
<Binding ElementName="txtSurname" Path="Validation.HasError"/>
<Binding ElementName="txtAddress" Path="Validation.HasError"/>
</MultiBinding>
</DataTrigger.Binding>
<Setter Property="IsEnabled" Value="False"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
My Converter looks like that
public class Converters : IMultiValueConverter
{
#region IMultiValueConverter Members
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if(values !=null && values.Length > 0)
{
if (values.Cast<type>().Count(val => val) > 0)
return false;
return true;
}
return false;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
return null;
}
#endregion
}
However I get invalidCastException in this converter. What is a proper cast in that case? I thoght as if HasError is a bool type so I should cast to bool.

Answer 1

To show the error message in a tool tip put this into your Application.Resources:
<Style x:Key="textBoxInError" 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>
</Style>
( Example from http://msdn.microsoft.com/en-us/library/system.windows.controls.validation.errortemplate.aspx )
To enable/disable a button you could use something along the line of
<Button x:Name="btnOK" Content="OK" IsDefault="True" Click="btnOK_Click">
<Button.Style>
<Style TargetType="{x:Type Button}">
<Setter Property="IsEnabled" Value="false" />
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=txt1, Path=(Validation.HasError)}" Value="false" />
<Condition Binding="{Binding ElementName=txt2, Path=(Validation.HasError)}" Value="false" />
</MultiDataTrigger.Conditions>
<Setter Property="IsEnabled" Value="true" />
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
or you could implement ICommand and use command binding.
EDIT
Here is a fully working example. It displays a window with two TextBoxes. The Button is enabled if and only if both TextBoxes are non-empty. Create a project called ValidationDemo and put the following files in it:
MainWindow.xaml:
<Window x:Class="ValidationDemo.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="146" Width="223">
<Window.Resources>
<Style 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>
</Style>
</Window.Resources>
<Grid>
<Label Content="A" Height="28" HorizontalAlignment="Left" Margin="46,7,0,0" Name="label1" VerticalAlignment="Top" />
<TextBox Name="txtA" Text="{Binding Path=TextA, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" Height="23" HorizontalAlignment="Left" Margin="69,12,0,0" VerticalAlignment="Top" Width="120" />
<Label Content="B" Height="28" HorizontalAlignment="Left" Margin="46,39,0,0" Name="label2" VerticalAlignment="Top" />
<TextBox Name="txtB" Text="{Binding Path=TextB, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" Height="23" HorizontalAlignment="Left" Margin="69,41,0,0" VerticalAlignment="Top" Width="120" />
<Button Name="btnOk" Content="OK" Height="23" HorizontalAlignment="Left" Margin="114,70,0,0" VerticalAlignment="Top" Width="75" Click="btnOk_Click">
<Button.Style>
<Style TargetType="{x:Type Button}">
<Setter Property="IsEnabled" Value="false" />
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=txtA, Path=(Validation.HasError)}" Value="false" />
<Condition Binding="{Binding ElementName=txtB, Path=(Validation.HasError)}" Value="false" />
</MultiDataTrigger.Conditions>
<Setter Property="IsEnabled" Value="true" />
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
</Grid>
</Window>
MainWindow.xaml.cs:
using System.Windows;
namespace ValidationDemo
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private Model model = new Model();
public MainWindow()
{
InitializeComponent();
this.DataContext = this.model;
}
private void btnOk_Click(object sender, RoutedEventArgs e)
{
Application.Current.Shutdown();
}
}
}
Model.cs:
using System;
using System.ComponentModel;
namespace ValidationDemo
{
public class Model : INotifyPropertyChanged, IDataErrorInfo
{
public event PropertyChangedEventHandler PropertyChanged;
private string textA = string.Empty;
public string TextA
{
get
{
return this.textA;
}
set
{
if (this.textA != value)
{
this.textA = value;
this.OnPropertyChanged("TextA");
}
}
}
private string textB = string.Empty;
public string TextB
{
get
{
return this.textB;
}
set
{
if (this.textB != value)
{
this.textB = value;
this.OnPropertyChanged("TextB");
}
}
}
public string Error
{
get { throw new NotImplementedException(); }
}
public string this[string columnName]
{
get
{
string result = string.Empty;
switch (columnName)
{
case "TextA":
if (string.IsNullOrEmpty(this.textA))
{
result = "'A' must not be empty";
}
break;
case "TextB":
if (string.IsNullOrEmpty(this.textA))
{
result = "'B' must not be empty";
}
break;
}
return result;
}
}
protected virtual void OnPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
}

Answer 2

<Window.Resources>
<Style x:Key="ElementInError" TargetType="{x:Type FrameworkElement}">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="ToolTip"
Value="{Binding (Validation.Errors)[0].ErrorContent, RelativeSource={x:Static RelativeSource.Self}}"/>
</Trigger>
</Style.Triggers>
</Style>
</Window.Resources>
<!-- ... -->
<TextBox x:Name="txtName" Style="{StaticResource ElementInError}">
<!-- ... -->
</TextBox>
<!-- ... -->
<Button x:Name="OkButton" Content="Ok" Margin="5" Click="OkButton_Click">
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=txtName,Path=(Validation.HasError)}" Value="True">
<Setter Property="IsEnabled" Value="False" />
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>

Answer 3

If you create a validation summary you can bind the IsEnabled property of your "Run" button to it's HasErrors property.
You'll need to use an intermediate property or converter as you want the IsEnabled to be true when HasErrors is false (and vice versa).