add migration

src/utils/database/pagesOrder.js

@@ -4,14 +4,31 @@ const config = require('../../../config');
 const db = new Datastore({filename: `./${config.database}/pagesOrder.db`, autoload: true});
 
 /**
+ * Current DataStore preparation
  * Add initial row for RootPage
  */
 (async function() {
-  const initialData = {
-    page: '0',
-    order: []
+  const parentIdOfRootPages = '0';
+  const cbk = (resolve, reject) => (err, doc) => {
+    if (err) {
+      reject(err);
+    }
+
+    resolve(doc);
   };
-  await db.insert(initialData);
+
+  const order = await new Promise((resolve, reject) => {
+    db.findOne({page: parentIdOfRootPages}, cbk(resolve, reject));
+  });
+
+  if (!order) {
+    const initialData = {
+      page: '0',
+      order: []
+    };
+    await db.insert(initialData);
+  }
+
 }());
 
 module.exports = db;