Adds ability to call getValue if returned value object has method.

Author: hailwood

src/AttributeManager.php

@@ -143,11 +143,15 @@ public function getFieldValue(View $view)
     }
 
     $value = old($fieldName, $value);
+    
+    if (is_object($value) && method_exists($value, 'getValue')) {
+      $value = $value->getValue();
+    }
 
     if ($value instanceof Collection) {
       $value = $value->modelKeys();
     }
 
     return is_bool($value) ? intval($value) : $value;
   }
-}
+}