MVC Model Validation From Database

I have a very simple Model, that needs to get validated from Database

public class UserAddress
{
    public string CityCode {get;set;}
}

CityCode can have values that are only available in my database table.

I know i can do something like.

[HttpPost]
public ActionResult Address(UserAddress model)
{
    var connection = ; // create connection
    var cityRepository = new CityRepository(connection);

    if (!cityRepository.IsValidCityCode(model.CityCode))
    {
        // Added Model error
    }
}

This seems very WET as I have to use this model at lot of placed and adding the same logic each place seems like i am not using MVC Architecture properly.

So, what is the best pattern to validate model from Database ?

NOTE: Most of the validation are single field lookup from Database, other validation may include combination of field. But right now I am happy with single field lookup validation, as long as it is DRY and is not using too much reflection it is acceptable.

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P.S. If any one can hint me how to do a attribute based validation from Database, will be extremely greatful, and a bounty will be awarded.