cascadingdropdownfour.cs

public JsonResult GetCountries(string selectedValue)
{
	countries = new List();
	countries.Add(new SelectListItem { Text = "Select country", Value = "0" });
	switch (selectedValue)
	{
		case "1":
			countries.Add(new SelectListItem { Text = "United Kingdom", Value = "1" });
			countries.Add(new SelectListItem { Text = "Italy", Value = "2" });
			countries.Add(new SelectListItem { Text = "Greece", Value = "3" });
			break;
		case "2":
			// more countries
			break;
		case "3":
			// more countries
			break;
	}

	return Json(new SelectList(countries, "Value", "Text"));
}

public JsonResult GetCities(string selectedValue)
{
	cities = new List();
	cities.Add(new SelectListItem { Text = "Select city", Value = "0" });
	switch (selectedValue)
	{
		case "1":
			cities.Add(new SelectListItem { Text = "Glasgow", Value = "1" });
			cities.Add(new SelectListItem { Text = "London", Value = "2" });
			cities.Add(new SelectListItem { Text = "Edinburgh", Value = "3" });
			break;
		case "2":
			// more cities
			break;
		case "3":
			// more cities
			break;
		case "4":
			// more cities
			break;
		case "5":
			// more cities
			break;
		// more cases
	}

	return Json(new SelectList(cities, "Value", "Text"));
}