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Using Fluent Validation with WPF - Dead Simple
using System.Text.RegularExpressions;
using FluentValidation;
using WpfFluentValidationExample.ViewModels;
namespace WpfFluentValidationExample.Lib
{
public class UserValidator : AbstractValidator<UserViewModel>
{
public UserValidator()
{
RuleFor(user => user.Name)
.NotEmpty()
.WithMessage("Please Specify a Name.");
RuleFor(user => user.Email)
.EmailAddress()
.WithMessage("Please Specify a Valid E-Mail Address");
RuleFor(user => user.Zip)
.Must(BeAValidZip)
.WithMessage("Please Enter a Valid Zip Code");
}
private static bool BeAValidZip(string zip)
{
if (!string.IsNullOrEmpty(zip))
{
var regex = new Regex(@"\d{5}");
return regex.IsMatch(zip);
}
return false;
}
}
}
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:viewModels="clr-namespace:WpfFluentValidationExample.ViewModels" x:Class="WpfFluentValidationExample.Views.UserView"
Title="UserView" Height="300" MinWidth="500">
<Window.DataContext>
<viewModels:UserViewModel/>
</Window.DataContext>
<StackPanel>
<StackPanel Orientation="Horizontal">
<Label Content="Name" Margin="10"/>
<TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" Width="200" Margin="10">
<Validation.ErrorTemplate>
<ControlTemplate>
<StackPanel Orientation="Horizontal">
<!-- Placeholder for the TextBox itself -->
<AdornedElementPlaceholder x:Name="textBox"/>
<TextBlock Margin="10" Text="{Binding [0].ErrorContent}" Foreground="Red"/>
</StackPanel>
</ControlTemplate>
</Validation.ErrorTemplate>
</TextBox>
</StackPanel>
<StackPanel Orientation="Horizontal">
<Label Content="E-Mail" Margin="10"/>
<TextBox Text="{Binding Email, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" Width="200" Margin="10">
<Validation.ErrorTemplate>
<ControlTemplate>
<StackPanel Orientation="Horizontal">
<!-- Placeholder for the TextBox itself -->
<AdornedElementPlaceholder x:Name="textBox"/>
<TextBlock Margin="10" Text="{Binding [0].ErrorContent}" Foreground="Red"/>
</StackPanel>
</ControlTemplate>
</Validation.ErrorTemplate>
</TextBox>
</StackPanel>
<StackPanel Orientation="Horizontal">
<Label Content="Zip" Margin="10"/>
<TextBox Text="{Binding Zip, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" Width="200" Margin="10">
<Validation.ErrorTemplate>
<ControlTemplate>
<StackPanel Orientation="Horizontal">
<!-- Placeholder for the TextBox itself -->
<AdornedElementPlaceholder x:Name="textBox"/>
<TextBlock Margin="10" Text="{Binding [0].ErrorContent}" Foreground="Red"/>
</StackPanel>
</ControlTemplate>
</Validation.ErrorTemplate>
</TextBox>
</StackPanel>
<Button Margin="10">Submit</Button>
</StackPanel>
</Window>
using System.Windows;
using WpfFluentValidationExample.ViewModels;
namespace WpfFluentValidationExample.Views
{
/// <summary>
/// Interaction logic for UserView.xaml
/// </summary>
public partial class UserView : Window
{
public UserView()
{
InitializeComponent();
DataContext = new UserViewModel();
}
}
}
using System;
using System.ComponentModel;
using System.Linq;
using WpfFluentValidationExample.Lib;
namespace WpfFluentValidationExample.ViewModels
{
public class UserViewModel : INotifyPropertyChanged, IDataErrorInfo
{
private readonly UserValidator _userValidator;
private string _zip;
private string _email;
private string _name;
public UserViewModel()
{
_userValidator = new UserValidator();
}
public string Name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("Name");
}
}
public string Email
{
get { return _email; }
set
{
_email = value;
OnPropertyChanged("Email");
}
}
public string Zip
{
get { return _zip; }
set
{
_zip = value;
OnPropertyChanged("Zip");
}
}
public string this[string columnName]
{
get
{
var firstOrDefault = _userValidator.Validate(this).Errors.FirstOrDefault(lol => lol.PropertyName == columnName);
if (firstOrDefault != null)
return _userValidator != null ? firstOrDefault.ErrorMessage : "";
return "";
}
}
public string Error
{
get
{
if (_userValidator != null)
{
var results = _userValidator.Validate(this);
if (results != null && results.Errors.Any())
{
var errors = string.Join(Environment.NewLine, results.Errors.Select(x => x.ErrorMessage).ToArray());
return errors;
}
}
return string.Empty;
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
@karelkral

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@karelkral karelkral commented Aug 27, 2018

Thank you for excellent example!

@mrNo0b

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@mrNo0b mrNo0b commented Feb 5, 2021

That's what I call Life Saver!! Thank you very much!

question: In UserViewModel.cs ln54, if I change the code to this:

_userValidator.Validate(this, options => options.IncludeProperties(columnName));

it will only check single rule from what I understood, will it be "faster"?

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