I am currently facing an issue with my JavaScript code related to cascading dropdowns. The setup involves having one dropdown for selecting a car brand and another dropdown for choosing a specific model under that brand. The functionality should work in such a way that when a brand is selected, the corresponding models should populate the second dropdown. To achieve this, I use a method called GetModelsJson in the controller to fetch the data from Brand and Model tables and return it as JSON.
public JsonResult GetModelsJson(int p)
{
var models = (from x in GetModels()
join y in GetBrands() on x.BrandId equals y.Id
where x.BrandId == p
select new
{
Text = x.Name,
Value = x.Id.ToString()
}).ToList();
return new JsonResult(new { data = models });
}
When rendering the view, I utilize the following code:
@Html.Label("Brands")
@Html.DropDownList("drpBrand",Model.BrandList,"--Select Brand--", new {@class = "form-control"})
@Html.Label("Models")
@Html.DropDownList("drpModel",Model.ModelList,"--Select Model--", new {@class = "form-control"})
The problem arises within the JavaScript section where issues occur during a for loop execution. Strangely, the length of the data variable along with its fields like text and value are showing up as undefined.
<script src="~/lib/jquery/dist/jquery.min.js"></script>
<script>
$(function(){
$('#drpBrand').change(function(){
var id = $('#drpBrand').val();
$.ajax({
url: '/Admin/Vehicle/GetModelsJson',
data: {p : id},
type: "POST",
dataType: "Json",
success: function(data){
console.log(data);
$('#drpModel').empty();
for (let i = 0; i < 3; i++){
$('#drpModel').append("<option value ='" + data[i].value + "'>" + data[i].text + "</option>");
}
}
});
});
});
</script>
This issue results in the second dropdown for models showing up as empty. Snapshot of the website interface
Despite the console displaying the data fields like "A5", "A4", "A6", the second dropdown remains empty as depicted in the image.