TextBoxLineCountBehavior: Fixed issue with UpdateAttachedProperties being called after detached causing NullReferenceException (#3769)

JorisCleVR · web-flow · commit 0ff7d5da9788 · 2025-01-12T23:51:16.000-08:00
diff --git a/src/MaterialDesignThemes.Wpf/Behaviors/TextBoxLineCountBehavior.cs b/src/MaterialDesignThemes.Wpf/Behaviors/TextBoxLineCountBehavior.cs
@@ -12,8 +12,11 @@ public class TextBoxLineCountBehavior : Behavior<TextBox>
 
     private void UpdateAttachedProperties()
     {
-        AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxLineCountProperty, AssociatedObject.LineCount);
-        AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxIsMultiLineProperty, AssociatedObject.LineCount > 1);
+        if (AssociatedObject != null)
+        {
+            AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxLineCountProperty, AssociatedObject.LineCount);
+            AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxIsMultiLineProperty, AssociatedObject.LineCount > 1);
+        }
     }
 
     protected override void OnAttached()

Original file line number	Diff line number	Diff line change
`@@ -12,8 +12,11 @@ public class TextBoxLineCountBehavior : Behavior<TextBox>`
`12`	`12`
`13`	`13`	`private void UpdateAttachedProperties()`
`14`	`14`	`{`
`15`		`- AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxLineCountProperty, AssociatedObject.LineCount);`
`16`		`- AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxIsMultiLineProperty, AssociatedObject.LineCount > 1);`
	`15`	`+ if (AssociatedObject != null)`
	`16`	`+ {`
	`17`	`+ AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxLineCountProperty, AssociatedObject.LineCount);`
	`18`	`+ AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxIsMultiLineProperty, AssociatedObject.LineCount > 1);`
	`19`	`+ }`
`17`	`20`	`}`
`18`	`21`
`19`	`22`	`protected override void OnAttached()`