C++ Drogon framework model-based ORM - c++

Question

I've began to learning C++ Drogon framework. I read the official and unofficial documents about the Drogon ORM. But I couldn't realized how can I create a model-based ORM database.
I want to create my models then run a migration command to map models to database tables.
If there is any document and guide about Drogon model-based ORM please let me know.
Thank you.

Answer 1

You can use
drogon::app().loadConfigFile("../config-name.json");
then run your sql command under drogon plugins after the program run. It's also will shutdown your custom plugin after the program exit.
It's require config files, where you can add your plugin on config-name.json.
steps:
1. create plugins
You can run from drogon_ctl create plugin <[namespace::]class_name> or create it manually.
Assume that your project root name is MyProject and says that your plugin class_name is my_plugin_01.
Do note that you also need to add both files to cmake add_executable.
add_executable(${PROJECT_NAME} "main.h" "main.cc"
...
"controllers/foo.h" "controllers/foo.cc"
"filters/bar.h" "filters/bar.cc"
...
"plugins/my_plugin_01.h" "plugins/my_plugin_01.cc")
2. add your plugin name to drogon loadConfigFile, which is config-name.json
{
"listeners": [
// your list of addresses and ports
],
...
// some of your config and so on
...
"plugins": [
{
"name": "MyProject::plugins::my_plugin_01",
"dependencies": [],
"config":
{
}
}
]
}
3. inside of my_plugin_01
my_plugin_01.h
#pragma once
#include <main.h>
#include <drogon/plugins/Plugin.h>
namespace MyProject
{
namespace plugins
{
class my_plugin_01 : public drogon::Plugin<my_plugin_01>
{
public:
my_plugin_01() {}
// This method must be called by drogon to initialize and start the plugin.
// It must be implemented by the user.
virtual void initAndStart(const Json::Value &config) override;
// This method must be called by drogon to shutdown the plugin.
// It must be implemented by the user.
virtual void shutdown() override;
};
} // namespace plugins
} // namespace MyProject
my_plugin_01.cc
#include "my_plugin_01.h"
using namespace drogon;
void MyProject::plugins::my_plugin_01::initAndStart(const Json::Value &config)
{
// Initialize and start the plugin
// Do your sql logic.
// Help: https://drogon.docsforge.com/master/database-general/database-dbclient/#execsqlasyncfuture
// log to console when DEBUG is true
if (MyProject::main::DEBUG)
{
std::cout << "\nPLUGIN INITIALIZE: my_plugin_01::initAndStart()\n\n";
}
}
void MyProject::plugins::my_plugin_01::shutdown()
{
// Shutdown the plugin
// Do your logic.
// log to console when DEBUG is true
if (MyProject::main::DEBUG)
{
std::cout << "\nPLUGIN SHUTDOWN: my_plugin_01::shutdown()\n\n";
}
}
Each time drogon::app().run(); your plugin/s will be initialze and terminate when program exit.
Another solution is use another framework/library from another programming language (e.g. dotnet, django and etc.)
You can do migration, create table and more from that framework/library.
This approach kinda neat but a bit complicated. Just be aware with your hardware resources.
Do this if you want to extend your logic, where heavy/intense workload use c++ and when some logic can not be achieved with c++, use another one.