Check for existing record in ICustomValidate of ASP.NET Boilerplate

Question

For ICustomValidate in ASP.NET Boilerplate, we can validate the value for the field.

I am wondering whether it is able and recommended to check whether the added name of the Student already exists, in the ICustomValidate.

For example, when creating a new student, we will check whether the student with the same name already exists. Can we move this logic to ICustomValidate?

Answer 1

You can:

public class CreateStudentDto : ICustomValidate
{
    public string Name { get; set; }

    public void AddValidationErrors(CustomValidationContext context)
    {
        using (var scope = context.IocResolver.CreateScope())
        {
            using (var uow = scope.Resolve<IUnitOfWorkManager>().Begin())
            {
                var studentRepository = scope.Resolve<IRepository<Student, long>>();

                var nameExists = studentRepository.GetAll()
                    .Where(s => s.Name == Name)
                    .Any();

                if (nameExists)
                {
                    var key = "A student with the same name already exists";
                    var errorMessage = context.Localize("sourceName", key);
                    var memberNames = new[] { nameof(Name) };
                    context.Results.Add(new ValidationResult(errorMessage, memberNames));
                }

                uow.Complete();
            }
        }
    }
}

But such validation is usually done in a domain manager, e.g. AbpUserManager

Custom Validation in the DTO would be recommended for invariant conditions:

public class CreateTaskInput : ICustomValidate
{
    public int? AssignedPersonId { get; set; }

    public bool SendEmailToAssignedPerson { get; set; }

    public void AddValidationErrors(CustomValidatationContext context)
    {
        if (SendEmailToAssignedPerson && (!AssignedPersonId.HasValue || AssignedPersonId.Value <= 0))
        {
            var errorMessage = "AssignedPersonId must be set if SendEmailToAssignedPerson is true!";
            context.Results.Add(new ValidationResult(errorMessage));
        }
    }
}