Membina Perlaksanaan Transaksi SQL yang Teguh dalam Go dengan Rangka Kerja Generik

func basicTxn(db *sql.DB) error {
    // start a transaction
    tx, err := db.Begin()
    if err != nil {
        return err
    }
    defer func() {
        if r := recover(); r != nil {
            tx.Rollback()
        } else if err != nil {
            tx.Rollback()
        } else {
            tx.Commit()
        }
    }()

    // insert data into the orders table
    _, err = tx.Exec("INSERT INTO orders (id, customer_name, order_date) VALUES (1, 'John Doe', '2022-01-01')")
    if err != nil {
        return err
    }
    return nil
}

func TestSqlWriteExec_CreateOrderTxn(t *testing.T) {

    db := setupDatabase()
    // create a new SQL Write Executor
    err := dbutils.NewSqlTxnExec[OrderRequest, OrderProcessingResponse](context.TODO(), db, nil, &OrderRequest{CustomerName: "CustomerA", ProductID: 1, Quantity: 10}).
        StatefulExec(InsertOrder).
        StatefulExec(UpdateInventory).
        StatefulExec(InsertShipment).
        Commit()
    // check if the transaction was committed successfully
    if err != nil {
        t.Fatal(err)
        return
    }
    verifyTransactionSuccessful(t, db)
    t.Cleanup(
        func() { 
            cleanup(db)
            db.Close() 
        },
    )
}

func InsertOrder(ctx context.Context, txn *sql.Tx, order *OrderRequest, orderProcessing *OrderProcessingResponse) error {
    // Insert Order
    result, err := txn.Exec("INSERT INTO orders (customer_name, product_id, quantity) VALUES (, , )", order.CustomerName, order.ProductID, order.Quantity)
    if err != nil {
        return err
    }
    // Get the inserted Order ID
    orderProcessing.OrderID, err = result.LastInsertId()
    return err
}

func UpdateInventory(ctx context.Context, txn *sql.Tx, order *OrderRequest, orderProcessing *OrderProcessingResponse) error {
    // Update Inventory if it exists and the quantity is greater than the quantity check if it exists
    result, err := txn.Exec("UPDATE inventory SET product_quantity = product_quantity -  WHERE id =  AND product_quantity >= ", order.Quantity, order.ProductID)
    if err != nil {
        return err
    }
    // Get the number of rows affected
    rowsAffected, err := result.RowsAffected()
    if rowsAffected == 0 {
        return errors.New("Insufficient inventory")
    }
    return err
}

func InsertShipment(ctx context.Context, txn *sql.Tx, order *OrderRequest, orderProcessing *OrderProcessingResponse) error {
    // Insert Shipment
    result, err := txn.Exec("INSERT INTO shipping_info (customer_name, shipping_address) VALUES (, 'Shipping Address')", order.CustomerName)
    if err != nil {
        return err
    }
    // Get the inserted Shipping ID
    orderProcessing.ShippingID, err = result.LastInsertId()
    return err
}

type TxnFn[T any] func(ctx context.Context, txn *sql.Tx, processingReq *T) error
type StatefulTxnFn[T any, R any] func(ctx context.Context, txn *sql.Tx, processingReq *T, processedRes *R) error

// SQL Write Executor is responsible when executing write operations
// For dependent writes you may need to add the dependent data to processReq and proceed to the next function call
type SqlTxnExec[T any, R any] struct {
    db               *sql.DB
    txn              *sql.Tx
    txnFns         []TxnFn[T]
    statefulTxnFns []StatefulTxnFn[T, R]
    processingReq    *T
    processedRes     *R
    ctx              context.Context
    err              error
}

func (s *SqlTxnExec[T, R]) Commit() (err error) {
    defer func() {
        if p := recover(); p != nil {
            s.txn.Rollback()
            panic(p)
        } else if err != nil {
            err = errors.Join(err, s.txn.Rollback())
        } else {
            err = errors.Join(err, s.txn.Commit())
        }
        return
    }()

    for _, writeFn := range s.txnFns {
        if err = writeFn(s.ctx, s.txn, s.processingReq); err != nil {
            return
        }
    }

    for _, statefulWriteFn := range s.statefulTxnFns {
        if err = statefulWriteFn(s.ctx, s.txn, s.processingReq, s.processedRes); err != nil {
            return
        }
    }
    return
}