Contoh Penggunaam Transaction di CI4

TransactionModel.php

<?php namespace App\Models;

class TransactionModel
{
    protected $db;

    public function __construct()
    {
        $this->db = db_connect();
    }

    //transaction menggunakan Raw Query
    public function beli()
    {
        $sql_produk = "SELECT * FROM produk WHERE id=:id:";
        $produk_query = $this->db->query($sql_produk,['id'=>1]);
        $produk = $produk_query->getFirstRow();
        $stok = $produk->stok;
        $harga = $produk->harga;        
        $jumlah_pembelian = 2;
        $total_harga = $jumlah_pembelian * $harga;
        $stok = $stok-$jumlah_pembelian;
        
        $this->db->transBegin();
        
        try{
            $sql_update_stok = "UPDATE produk SET stok=:stok:";
            $this->db->query($sql_update_stok,['stok'=>$stok]);

            $sql_insert_pembelian = "INSERT INTO pembelian(id_user, id_produk, jumlah, total_harga) VALUES(:id_user:,:id_produk:,:jumlah:,:total_harga:)";
            $this->db->query($sql_insert_pembelian,[
                'id_user' => 1,
                'id_produk' => 1,
                'jumlah' => $jumlah_pembelian,
                'total_harga' => $total_harga,
            ]);
            $this->db->transCommit();
            return 'INSERT BERHASIL';
        }
        catch(\Exception $e){
            $this->db->transRollback();
            return $e->getMessage();
        }
    }

    //transaction menggunakan Query Builder
    public function beli2()
    {
        $produk_builder = $this->db->table('produk');
        $produk_builder->where('id',1);
        $produk = $produk_builder->get(1);
        $produk = $produk->getRow();
        $stok = $produk->stok;
        $harga = $produk->harga;        
        $jumlah_pembelian = 4;
        $total_harga = $jumlah_pembelian * $harga;
        $stok = $stok-$jumlah_pembelian;
        
        $this->db->transBegin();
        
        try{
            $data = [
                'stok' => $stok
            ];
            $produk_builder->update($data,['id'=>1]);

            $data_pembelian = [
                'id_user' => 1,
                'id_produk' => 1,
                'jumlah' => $jumlah_pembelian,
                'total_harga' => $total_harga,
            ];

            $pembelian_builder = $this->db->table('pembelian');

            $pembelian_builder->insert($data_pembelian);
            
            $this->db->transCommit();
            return 'INSERT BERHASIL';
        }
        catch(\Exception $e){
            $this->db->transRollback();
            return $e->getMessage();
        }
    }
}