app/Filament/Resources/StickerMappingMasterResource.php

@@ -89,7 +89,26 @@ class StickerMappingMasterResource extends Resource
 
                     })
                     ->searchable()
-                    ->required(),
+                    ->required()
+                    ->rules([
+                        function (callable $get, $record) {
+                            return function (string $attribute, $value, $fail) use ($get, $record) {
+                                $plantId = $get('plant_id');
+
+                                $query = StickerMappingMaster::where('plant_id', $plantId)
+                                    ->where('item_id', $value);
+
+                                // Ignore the current record when editing
+                                if ($record) {
+                                    $query->where('id', '!=', $record->id);
+                                }
+
+                                if ($query->exists()) {
+                                    $fail('Item Code already exist to the selected plant.');
+                                }
+                            };
+                        },
+                    ]),
                 ])
                 ->columns(2),