Validate model on initial request

问题:

I'm returning a model to my view on the initial load of a page, the model is populated from the DB, I want to validate the model so that when the user receives the page a validation summary show the errors if any.

I have tried using TryValidateModel(model) but this does not work, it does not update the ModelState, the reasion I assume is that it will only validate against what is populated from the ModelBinder

Is there anyway around this? I just want to validate the model first without the user having to post it back...

        [Authorize, HttpGet, ActionName("StepOne")]     public ActionResult StepOneGET(StepOneModel model)     {         var individual = _onsideService.Get(User.Identity.Name);          model.PersonalInformation = new PersonalInformationModel                                         {                                             FirstName = individual.FirstName,                                             LastName = individual.LastName,                                             DoB = individual.DateOfBirth.ToString("dd/MM/yyyy"),                                             Email = individual.DefaultEmail.EmailAddress,                                             Phone = individual.DefaultPhone.Number,                                             AddressLine1 = location.Address1,                                             AddressLine2 = location.Address2,                                             City = location.City,                                             PostCode = location.PostalCode,                                             Country = location.Country                                         };          // NOTE: Does not update ModelState         TryValidateModel(model);          // Need to return potential errors to user on page load          return View(model);          } 

回答1:

Here is a snippet provided in another question here at SO. I don't take any credit for it, but it should do exactly what you want.

public static IList<KeyValuePair<string, string>> GetErrors(object obj)     {         // get the name of the buddy class for obj         MetadataTypeAttribute metadataAttrib = obj.GetType().GetCustomAttributes(typeof(MetadataTypeAttribute), true).FirstOrDefault() as MetadataTypeAttribute;          // if metadataAttrib is null, then obj doesn't have a buddy class, and in such a case, we'll work with the model class         Type buddyClassOrModelClass = metadataAttrib != null ? metadataAttrib.MetadataClassType : obj.GetType();          var buddyClassProperties = TypeDescriptor.GetProperties(buddyClassOrModelClass).Cast<PropertyDescriptor>();         var modelClassProperties = TypeDescriptor.GetProperties(obj.GetType()).Cast<PropertyDescriptor>();          var errors = from buddyProp in buddyClassProperties                            join modelProp in modelClassProperties on buddyProp.Name equals modelProp.Name // as this is an inner join, it will return only the properties that are in both the buddy and model classes                            from attribute in buddyProp.Attributes.OfType<ValidationAttribute>() // get only the attributes of type ValidationAttribute                            where !attribute.IsValid(modelProp.GetValue(obj))                            select new KeyValuePair<string, string>(buddyProp.Name, attribute.FormatErrorMessage(string.Empty));          return errors.ToList();     } 

文章来源: Validate model on initial request