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")
    }
}