Корректный, хоть и грубый захват JSON'а

src/DAO/MySQLUserDAO.cpp

@@ -23,6 +23,18 @@ optional<User> MySQLUserDAO::GetByGUID(string guid)
 
 std::optional<User> MySQLUserDAO::GetByLogin(std::string login)
 {
+  auto sql_result = session_.sql("SELECT * FROM `up_and_down`.`users` WHERE (login = '" + login +  "') LIMIT 1;"s).execute();
+  list<mysqlx::Row> rows = sql_result.fetchAll();
+
+  if (rows.size())
+  {
+    auto row_data = *rows.begin();
+
+    string replicated_login = row_data[1].get<string>();
+
+    cout << "SUCCESS!" << endl;
+  }
+
   return nullopt;
 }