using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading;

using System.Threading.Tasks;

using FluentValidation;

using Microsoft.EntityFrameworkCore;

using System.ComponentModel.DataAnnotations;

using Newtonsoft.Json;

​

public class Program

{

    public static async Task Main()

    {

        var options = new DbContextOptionsBuilder<ApplicationDBContext>()

            .UseInMemoryDatabase(databaseName: "ApplicationDB")

            .Options;

​

        // Insert seed data into the database using one instance of the context

        using (var context = new ApplicationDBContext(options))

        {

            context.Mrekcs.Add(new Mrekc {GroupCode = "T", GroupRec = "123"});

            context.Mrekcs.Add(new Mrekc {GroupCode = "T", GroupRec = "321"});

            context.Mrekcs.Add(new Mrekc {GroupCode = "K", GroupRec = "123"});

            context.Mrekcs.Add(new Mrekc {GroupCode = "M", GroupRec = "123"});

            context.SaveChanges();

        }

​

        // Use a clean instance of the context to run the test

        using (var context = new ApplicationDBContext(options))

        {

            //MovieRepository movieRepository = new MovieRepository(context);

            List<Mrekc> mrekcs = context.Mrekcs.ToList();

            var _validator = new CreateGroupingCommandValidator(context);

            FluentValidation.Results.ValidationResult result = await _validator.ValidateAsync(new CreateGroupingCommand

                                                                     {

                                                                         GroupCode = "K",

                                                                         GroupRec = "123"

                                                                     });        

            Console.WriteLine(JsonConvert.SerializeObject(result, Formatting.Indented));

        }

    }

}

​

public class CreateGroupingCommandValidator : AbstractValidator<CreateGroupingCommand>

{

    private readonly IApplicationDBContext _context;

    public CreateGroupingCommandValidator(IApplicationDBContext context)

    {

        _context = context;

        RuleFor(v => v.GroupCode)

            .MaximumLength(50)

            .WithMessage("Maximum length is 50.")

            //.MustAsync(BeUniqueName)

            //.WithMessage("Already exists.")

            .NotEmpty()

            .WithMessage("Required.")

            .MustAsync((root, groupCode, context) => 

                 BeUniqueCompositeKey(groupCode, root.GroupRec, new CancellationToken())

            )

            .WithMessage("Duplicate Composite key: GroupCode & GroupRec");

        RuleFor(v => v.GroupRec)

            .MaximumLength(50)

            .WithMessage("Maximum length is 50.")

            //.MustAsync(BeUniqueName)

            //.WithMessage("Already exists.")

            .NotEmpty()

            .WithMessage("Required.");

        RuleFor(v => v.oDescription)

            .MaximumLength(50)

            .WithMessage("Maximum length is 50.");

    }

​

    private async Task<bool> BeUniqueName(string codename, CancellationToken cancellationToken)

    {

        return await _context.Mrekcs.AllAsync(x => x.GroupCode != codename, cancellationToken);

    }

    private async Task<bool> BeUniqueCompositeKey(string groupCode, string groupRec, CancellationToken cancellationToken)

    {

        return await _context.Mrekcs.AllAsync(x => x.GroupCode != groupCode && x.GroupRec != groupRec, cancellationToken);

    }

}

​

public interface IApplicationDBContext

{

    public DbSet<Mrekc> Mrekcs { get; set; }

}

​

public class ApplicationDBContext : DbContext, IApplicationDBContext

{

    public ApplicationDBContext(DbContextOptions<ApplicationDBContext> options) : base(options)

    {

​

    }

​

    public DbSet<Mrekc> Mrekcs { get; set; }

}

​

[PrimaryKey(nameof(GroupCode), nameof(GroupRec))]

public class Mrekc

{

    public string GroupCode { get; set; }

    public string GroupRec { get; set; }

    public string oDescription { get; set; }

}

​

public class CreateGroupingCommand

{

    public string GroupCode { get; set; }

    public string GroupRec { get; set; }

    public string oDescription { get; set; }

}