I'm trying to make a label [Required] only if the condition above is true

I'm trying to make a Register page and i want to require Job details(Company name, Position, etc) part if the user is actively working. But couldn't find the solution

need condition for FirmaXXX parts

Solution

I would say you implement a validator in your model that looks a little like this.

public class YourModelClassName : IValidatableObject
{

  // Loads of properties Name, Phone yada yada...

  public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
  {
    if (EmployeeActive == true 
        && String.IsNullOrEmpty(CompanyName)
        && String.IsNullOrEmpty(Position)
        // add more if needed
       )
    {
      yield return new ValidationResult(
        // some message here.
        $"When you are an active employee you must fill in the basic data for your employment...",
        new[] { nameof(EmployeeActive) });
     }
  }
}