Model Hooks

Hooks run at specific points in a model's lifecycle. Use them to hash passwords, validate data, send notifications, update timestamps, or clean up related records.

Available Hooks

Hook	When	Common Uses
BeforeCreate	Before INSERT	Hash passwords, set defaults, generate UUIDs
AfterCreate	After INSERT	Send welcome email, create related records
BeforeUpdate	Before UPDATE	Validate changes, re-hash if password changed
AfterUpdate	After UPDATE	Invalidate cache, log changes
BeforeSave	Before INSERT or UPDATE	Slug generation, sanitize HTML
AfterSave	After INSERT or UPDATE	Sync search index, emit events
BeforeDelete	Before DELETE	Check constraints, archive data
AfterDelete	After DELETE	Clean up files, remove cached data

RegisterHooks

Use database.RegisterHooks to attach callbacks to a table. The Hooks struct lets you set any combination:

database.RegisterHooks(database.Get(), "users", database.Hooks{
    BeforeCreate: func(db *gorm.DB) {
        if u, ok := db.Statement.Dest.(*User); ok && u.Password != "" {
            hashed, _ := hash.Make(u.Password)
            u.Password = hashed
        }
    },
    AfterCreate: func(db *gorm.DB) {
        if u, ok := db.Statement.Dest.(*User); ok {
            // Send welcome email
            notification.Send(&WelcomeNotification{User: u})
        }
    },
    BeforeSave: func(db *gorm.DB) {
        if p, ok := db.Statement.Dest.(*Post); ok {
            // Auto-generate slug
            p.Slug = slugify(p.Title)
        }
    },
    AfterDelete: func(db *gorm.DB) {
        if p, ok := db.Statement.Dest.(*Post); ok {
            // Clean up uploaded images
            os.Remove(p.ImagePath)
        }
    },
})

Hooks Struct

type Hooks struct {
    BeforeCreate func(db *gorm.DB)
    AfterCreate  func(db *gorm.DB)
    BeforeUpdate func(db *gorm.DB)
    AfterUpdate  func(db *gorm.DB)
    BeforeSave   func(db *gorm.DB)
    AfterSave    func(db *gorm.DB)
    BeforeDelete func(db *gorm.DB)
    AfterDelete  func(db *gorm.DB)
}

// Only set the hooks you need — nil hooks are skipped

Accessing the Model

Inside hooks, access the model being saved/deleted via db.Statement.Dest:

BeforeUpdate: func(db *gorm.DB) {
    if u, ok := db.Statement.Dest.(*User); ok {
        // u is the User being updated
        u.UpdatedBy = getCurrentAdmin()
    }
}

Cache Invalidation Hook

Combine with cache invalidation:

database.RegisterHooks(db, "posts", database.Hooks{
    AfterSave: func(db *gorm.DB) {
        cache.Forget(ctx, "posts:list")
        cache.Forget(ctx, fmt.Sprintf("posts:%d", post.ID))
    },
    AfterDelete: func(db *gorm.DB) {
        cache.Forget(ctx, "posts:list")
    },
})

GORM Callbacks (Alternative)

For more control, use GORM's callback API directly:

db.Callback().Create().Before("gorm:before_create").Register("hash_password", func(db *gorm.DB) {
    // ...
})