How to Simplify Cascading Dropdowns in ASP.NET MVC 3 with C#?
Jan 11, 2025 pm 03:46 PM
Simplify cascading drop-down menu using C# in ASP.NET MVC 3
Creating cascading drop-down menus (where the options of one drop-down menu depend on the selection of another drop-down menu) can seem like a daunting task. However, with ASP.NET MVC 3 and C#, it can be made very simple.
Data Modeling
Start by defining a model to represent your data:
public class MyViewModel
{
public int? Year { get; set; }
public int? Month { get; set; }
public IEnumerable<SelectListItem> Years { get; set; }
}
Implement controller operation
Next, configure your controller action:
public class HomeController : Controller
{
public ActionResult Index()
{
var model = new MyViewModel { Years = GetYears() }; //獲取年份數(shù)據(jù)
return View(model);
}
public ActionResult Months(int year)
{
var months = GetMonths(year);
return Json(months, JsonRequestBehavior.AllowGet);
}
private IEnumerable<SelectListItem> GetYears()
{
// 此處替換為您的實(shí)際年份數(shù)據(jù)獲取邏輯
return Enumerable.Range(2010, 15).Select(year => new SelectListItem { Value = year.ToString(), Text = year.ToString() });
}
private IEnumerable<SelectListItem> GetMonths(int year)
{
// 此處替換為您的實(shí)際月份數(shù)據(jù)獲取邏輯, 考慮閏年
int maxMonth = (year == 2011) ? 3 : 12; // 示例，實(shí)際需根據(jù)年份判斷
return Enumerable.Range(1, maxMonth).Select(month => new SelectListItem { Value = month.ToString(), Text = month.ToString() });
}
}
Create View
Finally, in your view:
@model AppName.Models.MyViewModel
@Html.DropDownListFor(x => x.Year, Model.Years, "-- 選擇年份 --")
@Html.DropDownListFor(x => x.Month, Enumerable.Empty<SelectListItem>(), "-- 選擇月份 --")
<script>
$('#Year').change(function () {
var selectedYear = $(this).val();
if (selectedYear != null && selectedYear != '') {
$.getJSON('@Url.Action("Months")', { year: selectedYear }, function (months) {
var monthsSelect = $('#Month');
monthsSelect.empty();
$.each(months, function (index, month) {
monthsSelect.append($('<option>', {
value: month.Value,
text: month.Text
}));
});
});
}
});
</script>
Conclusion
Using this method, you can easily create cascading drop-down menus in ASP.NET MVC 3 using C#. The provided example provides a simple yet effective way to populate a second drop-down menu based on selections from the first drop-down menu, thus ensuring a user-friendly target user experience. Note that the GetYears and GetMonths methods have been improved in the code to make them more extensible, and use the SelectListItem type to make them more consistent with the specifications of the MVC framework. At the same time, the JavaScript code in the view has also been slightly adjusted to add options in a safer way.
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