A small validation library for WPF that uses a fluent interface and allow display messages near controls in GUI with MVVM Inspired FluentValidation by Jeremy Skinner
Install-Package ReactiveValidation
public class CarViewModel : ValidatableObject
{
public CarViewModel()
{
Validator = GetValidator();
}
private IObjectValidator GetValidator()
{
var builder = new ValidationBuilder<CarViewModel>();
builder.RuleFor(vm => vm.Make).NotEmpty();
builder.RuleFor(vm => vm.Model).NotEmpty().WithMessage("Please specify a car model");
builder.RuleFor(vm => vm.Mileage).GreaterThan(0).When(model => model.HasMileage);
builder.RuleFor(vm => vm.Vin).Must(BeAValidVin).WithMessage("Please specify a valid VIN");
builder.RuleFor(vm => vm.Description).Length(10, 100);
return builder.Build(this);
}
private bool BeAValidVin(string vin)
{
// custom vin validating logic goes here
}
//Properties with realization INotifyPropertyChanged goes here
}In xaml to control which displayed errors set attached property ReactiveValidation.AutoRefreshErrorTemplate equal True and binding your property
xmlns:b="clr-namespace:ReactiveValidation.WPF.Behaviors;assembly=ReactiveValidation"
...
<TextBox b:ReactiveValidation.AutoRefreshErrorTemplate="True"
Text="{Binding Make, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />Done!
You also can use template which display errors messages near control
To do this, set to attached property ReactiveValidation.ErrorTemplate value from static class ErrorTemplates.ExtendedErrorTemplate. If you are use default styles this will be look like this:
xmlns:b="clr-namespace:ReactiveValidation.WPF.Behaviors;assembly=ReactiveValidation"
xmlns:t="clr-namespace:ReactiveValidation.WPF.Templates;assembly=ReactiveValidation"
...
<ResourceDictionary>
<Style x:Key="TextBox" TargetType="TextBox">
<Setter Property="b:ReactiveValidation.AutoRefreshErrorTemplate" Value="True" />
<Setter Property="b:ReactiveValidation.ErrorTemplate" Value="{x:Static t:ErrorTemplates.ExtendedErrorTemplate}" />
</Style>
</ResourceDictionary>Apply style and nothing more!
<TextBlock Grid.Row="0" Grid.Column="0" Text="Make: " />
<TextBox Grid.Row="0" Grid.Column="1" Style="{StaticResource TextBox}"
Text="{Binding Make, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock Grid.Row="1" Grid.Column="0" Text="Model: " />
<TextBox Grid.Row="1" Grid.Column="1" Style="{StaticResource TextBox}"
Text="{Binding Model, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock Grid.Row="2" Grid.Column="0" Text="Has mileage: " />
<CheckBox Grid.Row="2" Grid.Column="1"
IsChecked="{Binding HasMileage, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock Grid.Row="3" Grid.Column="0" Text="Mileage: " />
<TextBox Grid.Row="3" Grid.Column="1" Style="{StaticResource TextBox}" IsEnabled="{Binding HasMileage}"
Text="{Binding Mileage, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock Grid.Row="4" Grid.Column="0" Text="Vin: " />
<TextBox Grid.Row="4" Grid.Column="1" Style="{StaticResource TextBox}"
Text="{Binding Vin, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock Grid.Row="5" Grid.Column="0" Text="Description: " />
<TextBox Grid.Row="5" Grid.Column="1" Style="{StaticResource TextBox}"
Text="{Binding Description, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />More samples you can find here