# Grouping Overview

The DropDownList enables you to bind it to a grouped data source.

To group the data, define a group `datasource` expression which uses a custom DataSource configuration, and specify the field by which the DropDownList will be grouped. For a runnable example, refer to the [demo on grouping in the DropDownList](https://demos.telerik.com/aspnet-core/dropdownlist/grouping).

> The data source sorts the grouped data either in ascending or descending order. To persist a specific group order, use the [server grouping feature](https://docs.telerik.com/kendo-ui/api/data/datasource#configuration-serverGrouping). To define the `serverGrouping` option, use the `ServerGrouping` method of the DataSource.

The following example demonstrates how to group the data in the DropDownList by country.

```Razor HtmlHelper
    @(Html.Kendo().DropDownList()
        .Name("customers")
        .DataSource(source =>  source
            .Custom()
            .Group(g => g.Add("Country", typeof(string)))
            .Transport(transport => transport
                .Read(read =>
                {
                    read.Action("Grouping_GetCustomers", "DropDownList");
                }))
            )
        .DataTextField("ContactName")
        .DataValueField("CustomerID")
    )
```

```Razor TagHelper
<kendo-dropdownlist name="customers"
                    datatextfield="ContactName"
                    datavaluefield="CustomerID">
    <datasource>
        <groups>
            <group field="Country"></group>
        </groups>
        <transport>
            <read url="@Url.Action("Grouping_GetCustomers", "DropDownList")" />
        </transport>
    </datasource>
</kendo-dropdownlist>
```

## See Also

* [Grouping by the DropDownList HtmlHelper for ASP.NET Core (Demo)](https://demos.telerik.com/aspnet-core/dropdownlist/grouping)
* [Server-Side API](https://www.telerik.com/aspnet-core-ui/documentation/api/dropdownlist)