Fluent Validation - WPF implementation

Working with FluentValidation makes my validation code cleaner and easier to integrate with the main application. I started removing my Enterprise library validation attributes and created Validators for my entities. The next major step was to integrate it with WPF. I have mentioned in one of my earlier posts on how to achieve this by implementing IDataErrorInfo on the business entities. Well, I had to follow the same approach for the FluentValidation classes also.

Here’s some sample code on the POC.

My BaseEntity class remains almost same, but with less code and looks clean

[Serializable]

public abstract class BaseEntity : INotifyPropertyChanged, IDataErrorInfo

{

    public T Id { get; set; }

    public Guid CreatedBy { get; set; }

    public Guid ChangedBy { get; set; }

    public DateTime CreatedDtTm { get; set; }

    public DateTime ChangedDtTm { get; set; }

    public Byte[] Version { get; set; }

    public void RaisePropertyChanged(params string[] propertyName)

    {

        propertyName.ToList().ForEach(x =>

        {

            if (PropertyChanged != null)

                PropertyChanged(this, new PropertyChangedEventArgs(x));

        });

    }

    [field: NonSerialized]

    public event PropertyChangedEventHandler PropertyChanged;

    public abstract ValidationResult SelfValidate();

    public bool IsValid

    {

        get { return SelfValidate().IsValid; }

    }

    public string Error

    {

        get { return ValidationHelper.GetError(SelfValidate()); }

    }

    public string this[string columnName]

    {

        get

        {

            var __ValidationResults = SelfValidate();

            if (__ValidationResults == null) return string.Empty;

            var __ColumnResults = __ValidationResults.Errors.FirstOrDefault<ValidationFailure>(x => string.Compare(x.PropertyName, columnName, true) == 0);

            return __ColumnResults != null ? __ColumnResults.ErrorMessage : string.Empty;

        }

    }

}

My Employee entity type inherits from the BaseEntity

public class Employee : BaseEntity<Guid>

{

    public string Code

    {

        get { return ___Code; }

        set

        {

            if (___Code != value)

            {

                ___Code = value;

                RaisePropertyChanged("Code");

            }

        }

    }

    public string FirstName

    {

        get { return ___FirstName; }

        set

        {

            if (___FirstName != value)

            {

                ___FirstName = value;

                RaisePropertyChanged("FirstName");

            }

        }

    }

    public string Email

    {

        get { return ___Email; }

        set

        {

            if (___Email != value)

            {

                ___Email = value;

                RaisePropertyChanged("Email");

            }

        }

    }

   

    public DateTime DateOfJoining

    {

        get { return ___DateOfJoining; }

        set

        {

            if (___DateOfJoining != value)

            {

                ___DateOfJoining = value;

                RaisePropertyChanged("DateOfJoining");

            }

        }

    }

    public List<EmployeeBenefit> Benefits { get; set; }

    public override ValidationResult SelfValidate()

    {

        return ValidationHelper.Validate<EmployeeValidator, Employee>(this);

    }

    string ___Code;

    string ___FirstName;

    string ___Email;

    DateTime ___DateOfJoining;

}

The validation logic for the Employee entity is available in the EmployeeValidator class

public class EmployeeValidator : AbstractValidator<Employee>

{

    public EmployeeValidator()

    {

        RuleFor<string>(x => x.Code).Length(5, 10)

            .WithMessage("Code" + ValidationConstants.StringLengthValidation + "5 - 10").WithPropertyName("Code");

        RuleFor<string>(x => x.FirstName).Length(1, 25)

            .WithMessage("FirstName" + ValidationConstants.StringLengthValidation + "1 - 25").WithPropertyName("FirstName");       

        RuleFor<string>(x => x.Email).EmailAddress()

            .WithMessage("Email" + ValidationConstants.NotValidValidation).WithPropertyName("Email");

        RuleFor<DateTime>(x => x.DateOfJoining).Must((x, y) => x.DateOfJoining < new DateTime(1900, 1, 1) || x.DateOfJoining > DateTime.Now)

            .WithMessage("Date of joining should be between 01-Jan-1900 and today").WithPropertyName("DateOfJoining");

    }

}

ValidationHelper class has two main methods that returns a string message for the failed validations and a Validator method to validate the entity.

public static ValidationResult Validate(K entity)

    where T : IValidator, new()

    where K : class

{

    IValidator __Validator = new T();

    return __Validator.Validate(entity);

}

public static string GetError(ValidationResult result)

{

    var __ValidationErrors = new StringBuilder();

    foreach (var validationFailure in result.Errors)

    {

        __ValidationErrors.Append(validationFailure.ErrorMessage);

        __ValidationErrors.Append(Environment.NewLine);

    }

    return __ValidationErrors.ToString();

}

Output