mchsamples-wpf-dotnet/ex_Validation/ex_ValidationWithAttributes/Person.cs

using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace ex_ValidationWithAttributes
{
    public class Person : IDataErrorInfo
    {
        public string Name { get; set; }


        /// <summary>
        /// Le prénom est requis et doit faire moins de 5 caractères 
        /// </summary>
        [Required]
        [MaxLength(5)]
        public string Surname { get; set; }


        /// <summary>
        /// L'Age est requis 
        /// </summary>
        [Required]
        public int? Age { get; set; }


        /// <summary>
        /// Méthode qui permet de chercher tous les attributs et de valider ceux-ci 
        /// </summary>
        /// <param name="columnName"></param>
        /// <returns></returns>
        public string this[string columnName]
        {
            get
            {

                var validationResults = new List<ValidationResult>();

                if (Validator.TryValidateProperty(
                    GetType().GetProperty(columnName).GetValue(this)
                    , new ValidationContext(this)
                    {
                        MemberName = columnName
                    }
                    , validationResults))
                    return null;

                return validationResults.First().ErrorMessage;
            }
        }

        public string Error { get; }
    }
}