Added new kb article raising-selectedindexchanged-server-side-radcomb…

…obox-multicolumncombobox

knowledge-base/raising-selectedindexchanged-server-side-radcombobox-multicolumncombobox.md

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+---
+title: Raising SelectedIndexChanged Server-Side for RadComboBox and MultiColumnComboBox
+description: This article explains how to raise the SelectedIndexChanged event server-side for RadComboBox and MultiColumnComboBox controls in ASP.NET AJAX. 
+type: how-to
+page_title: Raising SelectedIndexChanged Server-Side for RadComboBox and MultiColumnComboBox | Telerik UI for ASP.NET AJAX
+slug: raising-selectedindexchanged-server-side-radcombobox-multicolumncombobox
+tags: radcombobox, multicolumncombobox, selectedindexchanged, server-side, how-to
+res_type: kb
+---
+# Environment
+| Product | Version |
+| --- | --- |
+| RadComboBox for ASP.NET AJAX | all |
+
+# Description
+I want to raise the SelectedIndexChanged event server-side for RadComboBox and MultiColumnComboBox controls in my ASP.NET AJAX application. How can I achieve this?
+
+# Solution
+The SelectedIndexChanged event and similar events in web controls like RadComboBox and MultiColumnComboBox are designed to respond to user interactions in the browser. They are triggered when a user selects a new item from the drop-down list. However, programmatically changing the selection in server-side code does not automatically trigger the SelectedIndexChanged event.
+
+To programmatically set the selected value of a RadComboBox or MultiColumnComboBox and ensure that the SelectedIndexChanged event is fired server-side, you can use one of the following approaches:
+
+## Manual Event Invocation
+1. Set the selected value programmatically.
+2. Invoke the SelectedIndexChanged event handler manually after setting the selected value.
+
+Example:
+
+```
+protected void Page_Load(object sender, EventArgs e)
+{
+    if (!IsPostBack)
+    {
+        // Set initial values programmatically
+        SetInitialValues();
+    }
+}
+
+private void SetInitialValues()
+{
+    // Setting RadComboBox value
+    RadComboBox1.SelectedValue = "2";
+    
+    // Manually trigger the event
+    RadComboBox1_SelectedIndexChanged(RadComboBox1, new RadComboBoxSelectedIndexChangedEventArgs(
+        RadComboBox1.Text,
+        RadComboBox1.Text,
+        RadComboBox1.SelectedValue,
+        RadComboBox1.SelectedValue
+    ));
+
+    // Setting MultiColumnComboBox value
+    MultiColumnComboBox1.Value = "B";
+    
+    // Manually trigger the event
+    MultiColumnComboBox1_SelectedIndexChanged(MultiColumnComboBox1, EventArgs.Empty);
+}
+
+protected void RadComboBox1_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
+{
+    // Your logic here
+}
+
+protected void MultiColumnComboBox1_SelectedIndexChanged(object sender, EventArgs e)
+{
+    // Your logic here
+}
+```
+
+## Page Load Logic
+1. Set the selected value programmatically.
+2. Implement your logic within the Page_Load event, executing it conditionally based on whether it's a postback.
+
+Example:
+
+```
+protected void Page_Load(object sender, EventArgs e)
+{
+    if (IsPostBack)
+    {
+        // Execute the logic that would otherwise be in the SelectedIndexChanged event handler
+    }
+}
+```
+
+Remember, these workarounds mimic the behavior of the SelectedIndexChanged event and do not constitute an actual event firing as it would from a client-side action. Make sure to test thoroughly to ensure that your application behaves as expected.
+
+# See Also
+- [RadComboBox Documentation](https://docs.telerik.com/devtools/aspnet-ajax/controls/combobox/overview)
+- [MultiColumnComboBox Documentation](https://docs.telerik.com/devtools/aspnet-ajax/controls/multicolumncombobox/overview)
+