Virtualization in Blazor DropDown List Component

16 Mar 20221 minute to read

The DropDownList has been provided virtualization to improve the UI performance for a large amount of data when EnableVirtualization is true. This feature doesn’t render out the entire data source on initial component rendering. It loads the N number of items in the popup on initial rendering and the remaining set number of items will load on each scrolling action in the popup. It can work with both local and remote data.

In the following code, 150 items are bound to the component, but only 6 items will load to the popup when you open the popup. Remaining set number of items will load on each scrolling action in the popup.

@using Syncfusion.Blazor.DropDowns
@using Syncfusion.Blazor.Data 

<SfDropDownList TValue="string" TItem="Record" Placeholder="Select an item" DataSource="@Records" Query="@LocalDataQuery" PopupHeight="130px" EnableVirtualization="true">
    <DropDownListFieldSettings Text="Text" Value="ID"></DropDownListFieldSettings>
</SfDropDownList>

@code{
    public Query LocalDataQuery = new Query().Take(6); 
    public class Record 
    { 
        public string ID { get; set; } 
        public string Text { get; set; } 
    } 
    public List<Record> Records { get; set; } 
    protected override void OnInitialized()
    { 
        this.Records = Enumerable.Range(1, 150).Select(i => new Record() 
        { 
            ID = i.ToString(), 
            Text = "Item " + i, 
        }).ToList(); 
    } 
}