ASP.NET ComboBox - Load Items on Demand with Paging




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 handle the LoadingItems server-side event, which is executed each time the ComboBox
requests items from the server via AJAX. The server-side event handler will load all the items that match the text typed in the input field.

To improve the performance even further, you can use the "paging" approach for the load on demand feature.
Using this approach will force the ComboBox to load only a limited number at a time, instead of retrieving all the matches at once.
So for example, if there are 10,000 items in the database, you can configure the ComboBox to load 100 items at a time,
to make the on demand loading functionality run smoother.

To load the next set of items, the end user simply needs to click on the footer text from the bottom of the list with items.


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