I would suggest you a slightly different approach. You could handle the OnItemsRequested and perform the filtering at server side. Thus you could use the e.Text (typed in the input characters) and request a datasource, which would match/contains in the SearchColumn in your database. You could loop through the returned datasource (dataTable.Rows) and create the new RadComboBoxItem. Similar approach is implemented in this online demo
. Thus you would eliminate the need of managing the input Text of the RadComboBox and if the user selects an item, the DataTextField property would be displayed in the input.
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