add an auto increment id

include/orders.hpp

@@ -12,6 +12,6 @@ public:
   void write();
   void load();
   orders(const with_data_directory &);
-  void push();
+  void push(json);
   ~orders();
 };

src/orders.cpp

@@ -38,3 +38,8 @@ void orders::write() {
 }
 
 orders::~orders() { write(); }
+
+void orders::push(json data) {
+  data["id"] = std::to_string(size() + 1);
+  push_back(data);
+}

src/store.cpp

@@ -86,7 +86,7 @@ int Application::run() {
           return response::bad_request(response, v.errors());
         }
 
-        orders.push_back(data);
+        orders.push(data);
         orders.write();
 
         response->write(Status::success_created, data.dump(),