Conditional Sub-model Validation MVC 4 C#

Question

I have the following problem (I will simplify the classes to facilitate understanding):

public class Class1 {
    [Required]
    public int? Id_Estabelecimento { get; set; }
    public string Nm_Nome { get; set; }
}

public class Class2 {
    [Required]
    public int Id_Classe2 { get; set; }
    public int Tipo_Cadastro { get; set; }
    public Classe1 CLASSE1 { get; set; }
}

The problem is this: If Type is 1, the CLASSE1 (and its attributes) should not be Required, if 2 is the class should be validated normally.

OBS1: I can do this in Controller (using Modelstate Clear), but I wanted to do it in Client Side with jquery unobtrusive.

OBS2: I know it involves a conditional validation. I have already made a conditional validation involving two attributes of the same class. In this case I am wanting to "invade" the data Annotations of another class.

Has anyone ever been through anything like this?
Or am I complicating things?

Answer 1

Is complicating yes. Never validation may be different because of client switching.

In fact, clean up the ModelState is a bad practice in almost all cases.

Implement your Class2 as follows:

public class Class2 : IValidatableObject
{
    [Key]
    public int Class2Id { get; set; }
    [Required]
    public int TipoCadastro { get; set; }

    public virtual Classe1 Classe1 { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 
    { 
        if (TipoCadastro == 1) { 
            // Coloque a validação aqui. Dando erro, retorne um ValidationResult.
            yield return new ValidationResult("Campos tal e tal são obrigatórios.");
        }
    }
}

To indicate a certain field, add a array of Strings at the end, indicating for which fields the message covers:

yield return new ValidationResult("Campo Nome é obrigatório.", new string[] { "Nome" });