Hooks

Hooks are lifecycle callbacks that run before or after CRUD operations. Implement them as methods on your model struct.

Available Hooks

Hook	Triggered By	When
BeforeCreate	Create, CreateMany	Before insert, after timestamps and ID generation
AfterCreate	Create, CreateMany	After successful insert
BeforeSave	Update	Before replace, after fetching existing doc
AfterSave	Update	After successful replace
BeforeDelete	Delete	Before delete
AfterDelete	Delete	After successful delete

Interfaces

Each hook is a single-method interface:

type BeforeCreate interface {
    BeforeCreate(ctx context.Context) error
}

type AfterCreate interface {
    AfterCreate(ctx context.Context) error
}

type BeforeSave interface {
    BeforeSave(ctx context.Context) error
}

type AfterSave interface {
    AfterSave(ctx context.Context) error
}

type BeforeDelete interface {
    BeforeDelete(ctx context.Context) error
}

type AfterDelete interface {
    AfterDelete(ctx context.Context) error
}

Implementing Hooks

Add the hook method to your model with a pointer receiver:

type User struct {
    goodm.Model `bson:",inline"`
    Email       string `bson:"email" goodm:"unique,required"`
    Name        string `bson:"name"  goodm:"required"`
}

func (u *User) BeforeCreate(ctx context.Context) error {
    // Normalize email
    u.Email = strings.ToLower(u.Email)
    return nil
}

func (u *User) AfterCreate(ctx context.Context) error {
    log.Printf("User created: %s", u.Email)
    return nil
}

func (u *User) BeforeSave(ctx context.Context) error {
    log.Printf("Saving user: %s", u.ID.Hex())
    return nil
}

func (u *User) BeforeDelete(ctx context.Context) error {
    log.Printf("Deleting user: %s", u.ID.Hex())
    return nil
}

Error Handling

If a hook returns an error, the operation is aborted and the error is returned to the caller:

func (u *User) BeforeCreate(ctx context.Context) error {
    if strings.Contains(u.Email, "+") {
        return fmt.Errorf("email aliases not allowed")
    }
    return nil
}

Execution Order

For Create:

ID generation → Timestamps → BeforeCreate → Validate → InsertOne → AfterCreate

For Update:

Fetch existing → BeforeSave → Immutable check → Validate → UpdatedAt → ReplaceOne → AfterSave

For Delete:

BeforeDelete → DeleteOne → AfterDelete

Which Operations Run Hooks?

Operation	Hooks	Notes
Create	BeforeCreate, AfterCreate	Full lifecycle
CreateMany	BeforeCreate, AfterCreate	Per model in the batch
Update	BeforeSave, AfterSave	Full lifecycle
Delete	BeforeDelete, AfterDelete	Full lifecycle
UpdateOne	None	Raw passthrough
DeleteOne	None	Raw passthrough
UpdateMany	None	Raw passthrough
DeleteMany	None	Raw passthrough
FindOne	None	Read-only
Find	None	Read-only