added additional field in parts template e layout

public/userarea/update_visible_parts.php

@@ -21,11 +21,37 @@ $value = ($value === 1) ? 1 : 0;
 $db = DBHandlerSelect::getInstance();
 $pdo = $db->getConnection();
 
-$stmt = $pdo->prepare("UPDATE template_mapping SET is_visible_parts = ? WHERE id = ? AND template_id = ?");
-$result = $stmt->execute([$value, $mapping_id, $template_id]);
+try {
+    $pdo->beginTransaction();
 
-if ($result) {
-    echo json_encode(['success' => true]);
-} else {
-    echo json_encode(['success' => false, 'message' => 'Failed to update is_visible_parts']);
+    if ($value === 1) {
+        // 1) Force ONLY ONE row visible_parts per template:
+        // set all to 0 for this template
+        $stmtReset = $pdo->prepare("
+            UPDATE template_mapping
+            SET is_visible_parts = 0
+            WHERE template_id = ?
+        ");
+        $stmtReset->execute([$template_id]);
+    }
+
+    // 2) Set requested mapping to 1 or 0
+    $stmtSet = $pdo->prepare("
+        UPDATE template_mapping
+        SET is_visible_parts = ?
+        WHERE id = ? AND template_id = ?
+    ");
+    $stmtSet->execute([$value, $mapping_id, $template_id]);
+
+    $pdo->commit();
+
+    echo json_encode([
+        'success' => true,
+        'template_id' => $template_id,
+        'mapping_id' => $mapping_id,
+        'value' => $value
+    ]);
+} catch (Exception $e) {
+    if ($pdo->inTransaction()) $pdo->rollBack();
+    echo json_encode(['success' => false, 'message' => $e->getMessage()]);
 }