event_publisher.php

<?php

// https://codeigniter.com/userguide3/general/creating_libraries.html
class EventPublisher {
    
    const SOURCE = 'admin'

    public function __construct($params, $resource_name)
    {
        $this->CI =& get_instance();
        $this->resource = $resource_name;
        
        // hold a single rabbitMQ connection.
        $this->connection;
    }
    
    public function publish($event_name, $payload)
    {
        $exchange_name = $this->build_exchange_name($this->resource);
        $event = $this->build_event($this->resource, $event_name, $payload);
        $routing_key = $this->build_routing_key($this->resource, $event_name);
        
        $channel = $this->connection->channel;
        $channel->exchange_declare($exchange_name, 'topic', false, false, false);
        $msg = new AMQPMessage($event);
        $channel->basic_publish($msg, $exchange_name, $routing_key);
        $channel->close();
    }
    
    private function build_routing_key($resource, $event_name)
    {
        // source.resource.event_name
        // admin.group.created
        // admin.group.deleted
        return SOURCE . '.' . $resource . '.' . $event_name
    }

    private function build_exchange_name($resource)
    {
        // lower case 
        // source.resource
        // admin.group
        return SOURCE . '.' . $resource
    }
    
    private function build_event($resource, $event_name, $payload)
    {
        /*
        return {
            eventType: capitalize($resource) . '.' . captialize($event_name),
            // eventType: 'GroupCreated',
            payload: $payload
            eventTimestamp: ISO8601 UTC
        }
        */
    }
}

?>

model_example.php

<?php

class Group_model extends CI_Model {

    public function __construct($params) 
    {
        // somehow we need to configure the resource name
        $this->load('event_publisher');
        $this->event->resource('Group')
    }

    public function create()
    {
        $this->name = $_POST['name'];
        $this->db->insert('groups', $this);
        $this->event->publish('created', $this);
    }

    public function update()
    {
        $this->name = $_POST['name'];
        $this->db->update('groups', $this, array('id' => $_POST['id']));
        $this->event->publish('created', $this);
    }

    public function delete()
    {
        $this->name = $_POST['name'];
        // need to send the full object that has been deleted
        $result = $this->db->get('groups') // where id = $POST_ID
        $this->db->delete('groups', arrapy('id' => $POST['id']));
        $this->event->publish('deleted', $result);
    }
}

?>