validation – Controller.ValidateModel方法.它是如何工作的？

public abstract class CompanyFormViewModelBase
{
    public CompanyFormViewModelBase()
    {
        Role = new CompanyRoleListViewModel();
        ContactPerson = new PersonListViewModel();
        Sector = new SectorListViewModel();
    }
    [Required]
    [Display(Name = "Company Name")]
    public string CompanyName { get; set; }
    public CompanyRoleListViewModel Role { get; set; }
    [Display(Name = "Contact Name")]
    public PersonListViewModel ContactPerson { get; set; }
    public SectorListViewModel Sector { get; set; }
}
public class AddCompanyViewModel : CompanyFormViewModelBase,IValidatableObject
{
    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        PlugandabandonEntities db = new PlugandabandonEntities();
        CompanyName = CompanyName.Trim();

        var results = new List<ValidationResult>();

        if (db.Company.Where(p => p.CompanyName.ToLower() == CompanyName.ToLower()).Count() > 0)
            results.Add(new ValidationResult("Company already exists.",new string[] { "CompanyName" }));
        return results;
    }
}

它使用“经典”使用如下：

[HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(Plugandabandon.ViewModels.AddCompanyViewModel model)
    {
        if (ModelState.IsValid)
        {
            CreateCompany(model);
            return RedirectToAction("Index");
        }
        else
        {
            return View(model);
        }
    }

但是我想把这个模型类用于另一个,ajax形式.
我有以下方法：

public JsonResult ReturnJsonAddingCompany(string companyName,int roleID,int sectorID,int personID)
    {
        Plugandabandon.ViewModels.AddCompanyViewModel model = new ViewModels.AddCompanyViewModel()
        {
            CompanyName = companyName,ContactPerson = new ViewModels.PersonListViewModel()
            {
                SelectedItem = personID
            },Role = new ViewModels.CompanyRoleListViewModel()
            {
                SelectedItem = roleID
            },Sector = new ViewModels.SectorListViewModel()
            {
                SelectedItem = sectorID
            }
        };

        ValidateModel(model);

        if (ModelState.IsValid)
        {
            CreateCompany(model);
        }
        else
        {
            throw new Exception("Company with such name already exists");
        }

        var list = Utils.CompanyList();
        return Json(list,JsonRequestBehavior.AllowGet);
    }

看着

ValidateModel(model);

线.如果模型是正确的 – 它工作正常.如果不正确 – 它会抛出异常并中断方法的继续执行(并返回异常以查看).另外,如果我设置断点

public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)

方法,它永远不会在无效的模型案例中调用！ (调用有效模型Validate方法).我想拥有像“经典”方法这样的行为,只需验证模型然后验证ModelState.IsValid.
ValidateModel(模型)的行为对我来说很奇怪,它是一个“黑盒子”……