/// <summary>
/// Assigns a key to the city, if it is filled.
/// </summary>
private void GenerateCityId()
{
string baseKey;
if (CityName.HasValue())
{
baseKey = CountryId.ToString();
if (StateId.HasValue)
{
baseKey += StateId.Value.ToString();
}
baseKey += CityName;
CityId = baseKey.ToMD5HashString();
}
}