Model Validation with View Model which is inherited from Business Object - asp.net-mvc-4

Question

In MVC4 app, I have some Business Objects which am inheriting as view model. I want to use DataAnnotations in view model rather than specifying it in Business Object. Is that possible.
Business Objects
public class Country
{
[Display(Name = "Country")]
public virtual int CountryId { get; set; }
public virtual string CountryName { get; set; }
public virtual string CountryCode { get; set; }
}
public class State : Country
{
[Display(Name = "State")]
public virtual int StateId { get; set; }
public virtual string StateName { get; set; }
public virtual string StateCode { get; set; }
}
public class City : State
{
public virtual int CityId { get; set; }
[Display(Name = "City")]
public virtual string CityName { get; set; }
}
View Model
public class Regional
{
public Regional()
{
Countries = new Collection<Country>();
States = new Collection<State>();
City = new City();
}
public Collection<Country> Countries { get; set; }
public Collection<State> States { get; set; }
[Required(ErrorMessage = "Required")]
public City City { get; set; }
}
Here in the above code, I am using data annotations for City Property.
The problem here am facing is,even if I don't have this required annotation the form getting validated for Country and State but not validating for City Name.
When I add the required annotation, it is still getting validated only for country and state but not city name.
Any ideas?
My View
#using (Html.BeginForm(Actions.AddCity, Controllers.AdminUtility, FormMethod.Post))
{
<div class="alert-error">
#Html.ValidationSummary()
</div>
<div class="row-fluid">
<fieldset class="form-horizontal">
<legend class="header">Add City</legend>
<div class="control-group">
#Html.LabelFor(m => m.City.CountryId, new { #class = "control-label" })
<div class="controls">
#Html.DropDownListFor(m => m.City.CountryId, new SelectList(Model.Countries, "CountryId", "CountryName"),"", new { #class = "chosen", data_placeholder = "Choose Country..." })
</div>
</div>
<div class="control-group">
#Html.LabelFor(m => m.City.StateId, new { #class = "control-label" })
<div class="controls">
#Html.DropDownListFor(m => m.City.StateId,new SelectList(Model.States, "StateId","StateName"), "",new { #class = "chosen", data_placeholder = "Choose State..." })
</div>
</div>
<div class="control-group">
#Html.LabelFor(m => m.City.CityName, new { #class = "control-label" })
<div class="controls">
#Html.TextBoxFor(m => m.City.CityName)
</div>
</div>
<div class="control-group">
<div class="controls">
<input type="submit" />
</div>
</div>
</fieldset>
</div>
}

Answer 1

Your validation is saying that the class is required. You want the CityName to be required, so in your scenario, no, you have to specify the attributes on the domain model.
Just a note - I don't think your domain model is very clear. City, State, and Country don't inherit from one another, they are just related. A State is in a country, it isn't a country... Also, you should always validate your domain objects since they may be populated from multiple sources. Your ViewModel would then have additional validation that is specific to that view -- maybe it has some additional data used for ui processing that doesn't need to be passed on to your domain, etc.