using FluentValidation;

using FluentValidation.Results;

using System;

using System.Linq;

using System.Text.Json;

​

public class Program

{

    public class User

    {

        public string Name

        {

            get;

            set;

        }

​

        public int Age

        {

            get;

            set;

        }

    }

​

    public class TestValidator : AbstractValidator<User>

    {

        public TestValidator()

        {

            RuleFor(x => x.Name).NotNull().WithSeverity(Severity.Error).WithErrorCode("OMS-001");

            RuleFor(x => x.Age).NotEqual(0).WithSeverity(Severity.Warning).WithErrorCode("OMS-002");

        }

    }

​

    public static void Main()

    {

        Console.WriteLine("Starting");

        var user = new User()

        {Name = "ABC"};

        var validator = new TestValidator();

        Console.WriteLine("Validating");

        var results = validator.Validate(user);

        var options = new JsonSerializerOptions{WriteIndented = true};

        string jsonString = JsonSerializer.Serialize(results, options);

        //Console.WriteLine(jsonString);

        if (!results.IsValid)

        {

            foreach (var failure in results.Errors)

            {

                options = new JsonSerializerOptions{WriteIndented = true};

                jsonString = JsonSerializer.Serialize(failure, options);

                Console.WriteLine(jsonString);

            }

        }

        else

        {

            Console.WriteLine("No errors");

        }

    }

}

​

public static class ValidationExtension

{

    public static bool HasError(this ValidationResult result)

    {

        if (result.IsValid)

            return false;

        return result.Errors.Count(x => x.Severity == 0) > 0;

    }

}