ASP.NET MVC ComboBox - Load Items On Demand


The items of the ComboBox can be loaded on-demand (via AJAX requests). The advantage of using this approach is that the items are loaded only when the end user types something into the input field. Thus, the page will load very fast because no item is loaded on page load.

In order to enable the on demand loading feature, set the EnableLoadOnDemand property to true.
You also need to specify an action method that will be used to load the items on demand, using the OnLoadingItems property. This action method will load all the items that match the text typed in the input field.
View - Aspx
 
    <% Html.Obout(new ComboBox("ComboBox1") 
    {                
        EnableLoadOnDemand = true,
        OnLoadingItems = "ComboBox/LoadingItems"
    }); %>
    
View - Razor
 
    @Html.Obout(new ComboBox("ComboBox1") 
    {                
        EnableLoadOnDemand = true,
        OnLoadingItems = "ComboBox/LoadingItems"
    })
    
Controller
 
    public JsonResult LoadingItems(ComboBoxLoadingItemsEventArgs args)
    {
        ComboBoxItemList items = GetFilteredCustomers(args.Text, 0);
            
        JsonResult result = new JsonResult
        {
            Data = new {
                Items = items
            },
            JsonRequestBehavior = JsonRequestBehavior.AllowGet
        };

        return result;
    }
    
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