How to Create Cascading Dropdowns in ASP.NET MVC 3 with C#?

Building Cascading Dropdowns in ASP.NET MVC 3 using C#

Developing web applications often requires implementing cascading dropdown lists, where the options in one dropdown depend on the selection in another. This tutorial demonstrates how to achieve this functionality using ASP.NET MVC 3 and C#.

Data Model:

Begin by defining a model to represent your data, encompassing year and month.

<code class="language-csharp">public class MyViewModel
{
    public int? Year { get; set; }
    public int? Month { get; set; }
    // ... other properties
}</code>

Controller Actions:

The controller manages the data retrieval and delivery to the view.

<code class="language-csharp">public class HomeController : Controller
{
    // ... other actions

    public ActionResult Months(int year)
    {
        // ... logic to retrieve months based on the selected year
    }
}</code>

View Implementation:

The Razor view uses helper methods to generate the dropdown lists and incorporates JavaScript for dynamic updates.

<code class="language-html">@Html.DropDownListFor(
    model => model.Year, 
    new SelectList(Model.Years, "Value", "Text"), 
    "-- Select Year --"
)

@Html.DropDownListFor(
    model => model.Month, 
    Enumerable.Empty<SelectListItem>(), 
    "-- Select Month --"
)

<script>
    $('#Year').change(function () {
        // ... AJAX call to update the month dropdown
    });
</script></code>

Client-Side JavaScript:

jQuery is used to handle the AJAX request triggered by the year dropdown change event. The request fetches the appropriate months from the controller's Months action and populates the month dropdown accordingly.

This approach allows for the seamless creation of cascading dropdowns in ASP.NET MVC 3, enhancing the user experience.

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