ASP.NET MVC DropDownList Implementation

Today, we are going to learn how to use DropDownList in MVC. We will also see how to set selected Item to ViewBag and show in DropDownList.

Remember

• While creating ViewBag, if our ViewBag name is the same as the Control that we used in HTML page, then we have no need to specify that ViewBag in HTML.
• It will automatically fetch particular ViewBag data to particular Controls.
• So, it is a best practice to keep ViewBag name the same as HTML Control, so as to save time and reduce code complexity.

Let's start MVC DropDownList implementation. 

 

STEP 1 - Create Controller DropDownController

 

Note - For demo purposes, I used a particular Controller for better understanding. You can use DropDownController Code as per your requirement.

See the code to initialize DropDownList.

 

DropDownController 

namespace MVCApplicationDropDownList.Controllers
{
    public class DropDownController : Controller
    {

        //DropDown : SelectListItem Define for Month & Year DropDownList.
        List<SelectListItem> ddlMonths = new List<SelectListItem>();
        List<SelectListItem> ddlYears = new List<SelectListItem>();

        // GET: DropDown
        public ActionResult Index(int? Year)    {...}


        //DropDown : GetYears() will fill Year DropDown and Return List.
        private SelectList GetYears(int? iSelectedYear)   {...}


        //DropDown : GetMonths() will fill Months as per selected Year and Return List.
        private SelectList GetMonths(int? iSelectedYear)  {...}
    }
}

Index Method 

// GET: DropDown
public ActionResult Index(int? Year)
{
    if (Year == null)
    {
        Year = DateTime.Now.Year;
    }

    ViewBag.linktoYearId = GetYears(Year);
    ViewBag.linktoMonthId = GetMonths(Year);
    return View();
}

Year Method 

//DropDown : GetYears() will fill Year DropDown and Return List.
private SelectList GetYears(int? iSelectedYear)
{
    int CurrentYear = DateTime.Now.Year;

    for (int i = 2010; i <= CurrentYear; i++)
    {
        ddlYears.Add(new SelectListItem
        {
            Text = i.ToString(),
            Value = i.ToString()
        });
    }

    //Default It will Select Current Year
    return new SelectList(ddlYears, "Value", "Text", iSelectedYear);

}

Month Method 

//DropDown : GetMonths() will fill Months as per selected Year and Return List.
private SelectList GetMonths(int? iSelectedYear)
{
    var months = Enumerable.Range(1, 12).Select(i => new
    {
            A = i,
            B = DateTimeFormatInfo.CurrentInfo.GetMonthName(i)
    });

    int CurrentMonth = 1; //January

    if(iSelectedYear == DateTime.Now.Year)
    {
        CurrentMonth = DateTime.Now.Month;
        months = Enumerable.Range(1, CurrentMonth).Select(i => new
        {
            A = i,
            B = DateTimeFormatInfo.CurrentInfo.GetMonthName(i)
        });
    }

    foreach (var item in months)
    {
        ddlMonths.Add(new SelectListItem { Text = item.B.ToString(), Value = item.A.ToString() });
    }

    //Default It will Select Current Month
    return new SelectList(ddlMonths, "Value", "Text", CurrentMonth);

}

STEP 2  Add Index View 

Just right click on Controller Index() method and add Index View(). 

 

 

Add the following JavaScript to Index.cshtml.

<script type="text/javascript">

    function ChangeYear(obj) {
        window.location.href = '@Url.Action("Index","DropDown")?Year=' + obj.value;
    }

</script>

Add DropDownList to Index.cshtml.

@using (Html.BeginForm())
{
    <div class="row" style="border:solid; border-width:thin; padding:20px; height:400px;">
        <div class="col-lg-12 text-center">
            <div class="row">
                <div class="col-lg-6" align="right">
                    @Html.DropDownList("linktoMonthId", null, "--Select--", new
               {
                   @id = "ddlMonths",
                   @class = "form-control",
                   @style = "width:200px"
               })
                </div>
                <div class="col-lg-6" align="left">
                    @Html.DropDownList("linktoYearId", null, "--Select--", new
               {
                   @id = "ddlYears",
                   @onChange = "return ChangeYear(this)",
                   @class = "form-control",
                   @style = "width:200px"
               })
                </div>
            </div>
        </div>
    </div>
}

Now, just clean & build solution. Press F5.

 

Screen 1

 

Screen 2
 

OK, that's it. Hope this tutorial makes sense regarding implementation of Dropdownlist in ASP.NET MVC.