Clean Database Transactions in Go with GORM

main.go

package main

import (
    "context"
    "fmt"
    "gorm.io/driver/sqlite"
    "gorm.io/gorm"
)

// Entity represents a database entity
type Entity struct {
    ID   uint
    Name string
}

// Repository defines the methods for database operations and transaction handling
type Repository interface {
    Create(ctx context.Context, entity *Entity) error
    Update(ctx context.Context, entity *Entity) error
    Transaction(ctx context.Context, fn func(repo Repository) error) error
}

// repository implements the Repository interface and holds the GORM DB instance
type repository struct {
    db *gorm.DB
}

// withTx creates a new repository instance with the given transaction
func (r *repository) withTx(tx *gorm.DB) Repository {
    return &repository{
        db: tx,
    }
}

// Transaction manages the transaction lifecycle
func (r *repository) Transaction(ctx context.Context, fn func(repo Repository) error) error {
    tx := r.db.Begin()
    if tx.Error != nil {
        return tx.Error
    }
    repo := r.withTx(tx)
    err := fn(repo)
    if err != nil {
        tx.Rollback()
        return err
    }
    return tx.Commit().Error
}

// Create adds a new entity to the database
func (r *repository) Create(ctx context.Context, entity *Entity) error {
    return r.db.Create(entity).Error
}

// Update modifies an existing entity in the database
func (r *repository) Update(ctx context.Context, entity *Entity) error {
    return r.db.Save(entity).Error
}

// Service handles the business logic
type Service struct {
    repo Repository
}

// PerformBusinessLogic performs multiple database operations within a transaction
func (s *Service) PerformBusinessLogic(ctx context.Context) error {
    return s.repo.Transaction(ctx, func(repo Repository) error {
        if err := repo.Create(ctx, &Entity{Name: "Example"}); err != nil {
            return err
        }
        return repo.Update(ctx, &Entity{ID: 1, Name: "Updated Example"})
    })
}

func main() {
    db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{})
    if err != nil {
        panic("failed to connect database")
    }

    // Migrate the schema
    db.AutoMigrate(&Entity{})

    repo := &repository{db: db}
    service := &Service{repo: repo}

    ctx := context.Background()
    if err := service.PerformBusinessLogic(ctx); err != nil {
        fmt.Printf("Transaction failed: %v\n", err)
    } else {
        fmt.Println("Transaction succeeded")
    }
}

Hi, thanks for the article. It's very interesting. I have the following question. Most applications consist of usecases, services, and repositories. How do you see the transaction being declared at the use case level, which executes atomic services?

When you say usecase, do you mean at the controller or handler level?

yes