Grouping in ASP.NET CORE DropDownList

25 Aug 20264 minutes to read

The DropDownList supports grouping list items into categories based on a data field. The category of each list item can be mapped through the groupBy field in the data table. The group header is displayed both as inline and fixed headers. The fixed group header updates dynamically as you scroll, displaying the current category.

In the following sample, vegetables are grouped by category using the groupBy field.

<div id='groupList' class='col-lg-6' style='padding-top:15px'>
    <div class='content'>
        <ejs-dropdownlist id="vegetables" placeholder="Select a vegetable" popupHeight="200px" dataSource="@ViewBag.data">
            <e-dropdownlist-fields groupBy="Category" value="Vegetable"></e-dropdownlist-fields>
        </ejs-dropdownlist>
    </div>
</div>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication1.Models
{
    public class Vegetables
    {
        public string Vegetable { get; set; }
        public string Category { get; set; }
        public string Id { get; set; }
        public List<Vegetables> VegetablesList()
        {
        List<Vegetables> veg = new List<Vegetables>();
        veg.Add(new Vegetables { Vegetable = "Cabbage", Category= "Leafy and Salad", Id= "item1" });
        veg.Add(new Vegetables { Vegetable = "Chickpea", Category= "Beans", Id= "item2" });
        veg.Add(new Vegetables { Vegetable = "Garlic", Category= "Bulb and Stem", Id= "item3" });
        veg.Add(new Vegetables { Vegetable = "Green bean", Category= "Beans", Id= "item4" });
        veg.Add(new Vegetables { Vegetable = "Horse gram", Category= "Beans", Id= "item5" });
        veg.Add(new Vegetables { Vegetable = "Nopal", Category= "Bulb and Stem", Id= "item6" });
        veg.Add(new Vegetables { Vegetable = "Onion", Category= "Bulb and Stem", Id= "item7" });
        veg.Add(new Vegetables { Vegetable = "Pumpkins", Category= "Leafy and Salad", Id= "item8" });
        veg.Add(new Vegetables { Vegetable = "Spinach", Category= "Leafy and Salad", Id= "item9" });
        veg.Add(new Vegetables { Vegetable = "Wheat grass", Category= "Leafy and Salad", Id= "item10" });
        veg.Add(new Vegetables { Vegetable = "Yarrow", Category = "Leafy and Salad", Id = "item11" });
         return veg;
        }
    }
}

Customization

The group header can be customized using the groupTemplate property for both inline and fixed headers as referred here:

Group Template support to DropDownList.