Windows Presentation Foundation
A part of the .NET Framework that provides a unified programming model for building line-of-business desktop applications on Windows.
2,784 questions
Hi, if you want to see default error information you can include your own conversion and use IDataError in dataobject like in following demo:
XAML:
<Window x:Class="WpfApp1.Window44"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApp44"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
mc:Ignorable="d"
Title="Demo Validation IDataError" Height="450" Width="800">
<Window.DataContext>
<local:ViewModel/>
</Window.DataContext>
<StackPanel x:Name="panel">
<StackPanel.BindingGroup>
<BindingGroup x:Name="ValidateAllFields" NotifyOnValidationError="True">
<BindingGroup.ValidationRules>
<local:ValidateAll ValidationStep="ConvertedProposedValue"/>
</BindingGroup.ValidationRules>
</BindingGroup>
</StackPanel.BindingGroup>
<StackPanel.Resources>
<DataTemplate DataType="{x:Type ValidationError}">
<TextBlock Text="{Binding ErrorContent}"/>
</DataTemplate>
</StackPanel.Resources>
<i:Interaction.Behaviors>
<local:StackPanelBehavior/>
</i:Interaction.Behaviors>
<StackPanel DataContext="{Binding View}">
<TextBox Margin="5">
<TextBox.Text>
<Binding Path="Name" BindingGroupName="ValidateAllFields" UpdateSourceTrigger="PropertyChanged"/>
</TextBox.Text>
</TextBox>
<TextBox Margin="5">
<TextBox.Text>
<Binding Path="Age" BindingGroupName="ValidateAllFields" UpdateSourceTrigger="PropertyChanged"/>
</TextBox.Text>
</TextBox>
</StackPanel>
<Button Content="Button to execute BindingGroup.CommitEdit" Command="{Binding Cmd}" Margin="5"/>
<StatusBar Margin="5 20 5 0">
<ContentPresenter Content="{Binding ElementName=panel, Path=(Validation.Errors).CurrentItem}"/>
</StatusBar>
</StackPanel>
</Window>
-----------------------------------
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Interactivity;
namespace WpfApp44
{
public class ViewModel
{
public Data View { get; set; } = new Data() { Name = "xxx" };
public ICommand Cmd { get => new RelayCommand((state) => { ValidateAllFields?.CommitEdit(); }, null); }
public BindingGroup ValidateAllFields { get; set; }
}
public class Data : IDataErrorInfo, INotifyPropertyChanged
{
private string _name = string.Empty;
public string Name
{
get => this._name;
set { this._name = value; errorMessages[nameof(Name)] = this[nameof(Name)]; OnPropertyChanged(); }
}
private int _age = 0;
private string _ageString = null;
public object Age
{
get => (this._ageString == null) ? this._age.ToString() : this._ageString;
set
{
if (value == null) this._ageString = "?";
else
{
this._ageString = value.ToString();
int.TryParse(value.ToString(), out this._age);
errorMessages[nameof(Age)] = this[nameof(Age)];
OnPropertyChanged();
}
}
}
private Dictionary<string, string> errorMessages = new Dictionary<string, string>();
public string Error
{
get
{
String result = String.Empty;
foreach (var item in errorMessages)
if (!string.IsNullOrEmpty(item.Value)) result += (string.IsNullOrEmpty(result)) ? item.Value : Environment.NewLine + item.Value;
return result;
}
}
public string this[string columnName]
{
get
{
string result = string.Empty;
switch (columnName)
{
case "Name": if (string.IsNullOrEmpty(Name)) result = "Name may not be null or empty"; break;
case "Age":
if (string.IsNullOrEmpty(this._ageString)) result = "Age may not be null or empty";
else if (this._age < 18 || this._age > 65) result = "Age must be beetween 18 an 65"; break;
};
return result;
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string propertyName = "") =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public class ValidateAll : ValidationRule
{
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
BindingGroup bindingGroup = (BindingGroup)value;
ViewModel vm = (ViewModel)bindingGroup.Items[0];
if (!string.IsNullOrEmpty(vm.View.Error)) return new ValidationResult(false, vm.View.Error);
return ValidationResult.ValidResult;
}
}
public class StackPanelBehavior : Behavior<StackPanel>
{
protected override void OnAttached()
{
var vm = AssociatedObject.DataContext as ViewModel;
var bg = AssociatedObject.BindingGroup;
if (vm == null || bg == null) return;
vm.ValidateAllFields = bg;
}
}
public class RelayCommand : ICommand
{
private readonly Predicate<object> _canExecute;
private readonly Action<object> _action;
public RelayCommand(Action<object> action) { _action = action; _canExecute = null; }
public RelayCommand(Action<object> action, Predicate<object> canExecute) { _action = action; _canExecute = canExecute; }
public void Execute(object o) => _action(o);
public bool CanExecute(object o) => _canExecute == null ? true : _canExecute(o);
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
}
}
