Merge pull request #1307 from telerik/new-kb-restricting-input-length-entry-radcombobox-maui-735d4125b26c4ee688cac77fcf4ee5eb

Added new kb article restricting-input-length-entry-radcombobox-maui

Author: didiyordanova

knowledge-base/restricting-input-length-entry-radcombobox-maui.md

@@ -0,0 +1,88 @@
+---
+title: Limiting Characters in Entry and ComboBox Controls in UI for .NET MAUI
+description: Learn how to limit the number of characters entered in Telerik MAUI Entry and RadComboBox controls while typing.
+type: how-to
+page_title: Restricting Input Length in Entry and RadComboBox for UI for .NET MAUI
+meta_title: Restricting Input Length in Entry and RadComboBox for UI for .NET MAUI
+slug: restricting-input-length-entry-radcombobox-maui
+tags: radentry, radcombobox, input-validation, ui for .net maui, entry, combobox, maxlength, textchanged
+res_type: kb
+---
+
+## Environment
+
+| Version | Product | Author | 
+| --- | --- | ---- | 
+| 12.0.0 | Telerik UI for .NET MAUI Entry | [Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | 
+| 12.0.0 | Telerik UI for .NET MAUI ComboBox| [Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | 
+
+## Description
+
+I want to restrict the number of characters typed in an Entry or ComboBox control in UI for .NET MAUI applications.
+
+This knowledge base article also answers the following questions:
+- How to set a maximum character limit in Telerik MAUI Entry?
+- How to access ComboBox's input and set character restrictions?
+- How can I handle text changes in ComboBox or Entry?
+
+## Solution for MAUI Entry
+
+The [Telerik MAUI Entry](https://www.telerik.com/maui-ui/documentation/controls/entry/overview) control provides a `MaxLength` property to define the maximum number of characters allowed. It also supports a `TextChanged` event to track text changes.
+
+```xml
+<telerik:RadEntry MaxLength="10" TextChanged="OnTextChanged" />
+```
+
+## Solution for MAUI ComboBox
+
+The [ComboBox](https://www.telerik.com/maui-ui/documentation/controls/combobox/overview) uses the `RadTextInput` control for text input when in editable mode. You can access `RadTextInput` through the `Loaded` event of `RadComboBox` and set the `MaxLength` property.
+
+```xml
+<VerticalStackLayout>
+    <telerik:RadComboBox ItemsSource="{Binding Locations}"
+                         DisplayMemberPath="City"
+                         IsEditable="True" 
+                         x:Name="combo"
+                         Loaded="RadComboBox_Loaded" />
+</VerticalStackLayout>
+```
+
+In the code-behind, access `RadTextInput` and define the character limit:
+
+```csharp
+private void RadComboBox_Loaded(object sender, EventArgs e)
+{
+    var textInput = ChildOfType<RadTextInput>(this.combo);
+    textInput.MaxLength = 4;
+    textInput.TextChanged += TextInput_TextChanged;
+}
+
+private void TextInput_TextChanged(object? sender, TextChangedEventArgs e)
+{
+    // Handle text changes if needed.
+}
+
+internal static T ChildOfType<T>(View visualElement) where T : View
+{
+    if (visualElement == null)
+    {
+        return null;
+    }
+    foreach (var item in VisualTreeElementExtensions.GetVisualTreeDescendants(visualElement))
+    {
+        if (item is T targetElement)
+        {
+            return targetElement;
+        }
+    }
+    return null;
+}
+```
+
+
+## See Also
+
+- [Entry Overview](https://www.telerik.com/maui-ui/documentation/controls/entry/overview)
+- [ComboBox Overview](https://www.telerik.com/maui-ui/documentation/controls/combobox/overview)
+- [Text Input Documentation](https://www.telerik.com/maui-ui/documentation/controls/entry/text-input)
+- [Entry Events Documentation](https://www.telerik.com/maui-ui/documentation/controls/entry/events)