core

Documentation

Overview

Package core contains domain events for the example: Book circulation in a public library.

This package implements domain events following proper domain-driven design patterns, avoiding CRUD-style antipatterns. Events represent meaningful business occurrences like BookCopyAddedToCirculation and BookCopyLentToReader rather than generic create/update operations.

All domain events implement the DomainEvent interface with EventType() and HasOccurredAt() methods for event sourcing integration.

In Domain-Driven Design or Hexagonal Architecture terminology, this would be called the 'domain' layer.

Index

• Constants
• type BookCopyAddedToCirculation
  • func BuildBookCopyAddedToCirculation(bookID uuid.UUID, isbn string, title string, authors string, edition string, ...) BookCopyAddedToCirculation
  • func (e BookCopyAddedToCirculation) EventType() string
  • func (e BookCopyAddedToCirculation) HasOccurredAt() time.Time
• type BookCopyLentToReader
  • func BuildBookCopyLentToReader(bookID uuid.UUID, readerID uuid.UUID, occurredAt time.Time) BookCopyLentToReader
  • func (e BookCopyLentToReader) EventType() string
  • func (e BookCopyLentToReader) HasOccurredAt() time.Time
• type BookCopyRemovedFromCirculation
  • func BuildBookCopyRemovedFromCirculation(bookID uuid.UUID, occurredAt time.Time) BookCopyRemovedFromCirculation
  • func (e BookCopyRemovedFromCirculation) EventType() string
  • func (e BookCopyRemovedFromCirculation) HasOccurredAt() time.Time
• type BookCopyReturnedByReader
  • func BuildBookCopyReturnedFromReader(bookID uuid.UUID, readerID uuid.UUID, occurredAt time.Time) BookCopyReturnedByReader
  • func (e BookCopyReturnedByReader) EventType() string
  • func (e BookCopyReturnedByReader) HasOccurredAt() time.Time
• type BookIDString
• type DomainEvent
• type DomainEvents
• type ISBNString
• type OccurredAtTS
  • func ToOccurredAt(t time.Time) OccurredAtTS
• type ProducedNewEventToAppendBool
• type ReaderIDString
• type SomethingHasHappened
  • func BuildSomethingHasHappened(id string, someInformation string, occurredAt time.Time, ...) SomethingHasHappened
  • func (e SomethingHasHappened) EventType() string
  • func (e SomethingHasHappened) HasOccurredAt() time.Time

Constants

const BookCopyAddedToCirculationEventType = "BookCopyAddedToCirculation"

BookCopyAddedToCirculationEventType is the event type identifier.

const BookCopyLentToReaderEventType = "BookCopyLentToReader"

BookCopyLentToReaderEventType is the event type identifier.

const BookCopyRemovedFromCirculationEventType = "BookCopyRemovedFromCirculation"

BookCopyRemovedFromCirculationEventType is the event type identifier.

const BookCopyReturnedByReaderEventType = "BookCopyReturnedByReader"

BookCopyReturnedByReaderEventType is the event type identifier.

const SomethingHasHappenedEventTypePrefix = "SomethingHasHappened"

SomethingHasHappenedEventTypePrefix is the prefix for dynamic event types.

Types

type BookCopyAddedToCirculation

type BookCopyAddedToCirculation struct {
	BookID          BookIDString
	ISBN            ISBNString
	Title           string
	Authors         string
	Edition         string
	Publisher       string
	PublicationYear uint
	OccurredAt      OccurredAtTS
}

BookCopyAddedToCirculation represents when a book copy is added to library circulation.

func BuildBookCopyAddedToCirculation

func BuildBookCopyAddedToCirculation(
	bookID uuid.UUID,
	isbn string,
	title string,
	authors string,
	edition string,
	publisher string,
	publicationYear uint,
	occurredAt time.Time,
) BookCopyAddedToCirculation

BuildBookCopyAddedToCirculation creates a new BookCopyAddedToCirculation event.

func (BookCopyAddedToCirculation) EventType

func (e BookCopyAddedToCirculation) EventType() string

EventType returns the event type identifier.

func (BookCopyAddedToCirculation) HasOccurredAt

func (e BookCopyAddedToCirculation) HasOccurredAt() time.Time

HasOccurredAt returns when this event occurred.

type BookCopyLentToReader

type BookCopyLentToReader struct {
	BookID     BookIDString
	ReaderID   ReaderIDString
	OccurredAt OccurredAtTS
}

BookCopyLentToReader represents when a book copy is lent to a reader.

func BuildBookCopyLentToReader

func BuildBookCopyLentToReader(bookID uuid.UUID, readerID uuid.UUID, occurredAt time.Time) BookCopyLentToReader

BuildBookCopyLentToReader creates a new BookCopyLentToReader event.

func (BookCopyLentToReader) EventType

func (e BookCopyLentToReader) EventType() string

EventType returns the event type identifier.

func (BookCopyLentToReader) HasOccurredAt

func (e BookCopyLentToReader) HasOccurredAt() time.Time

HasOccurredAt returns when this event occurred.

type BookCopyRemovedFromCirculation

type BookCopyRemovedFromCirculation struct {
	BookID     BookIDString
	OccurredAt OccurredAtTS
}

BookCopyRemovedFromCirculation represents when a book copy is removed from library circulation.

func BuildBookCopyRemovedFromCirculation

func BuildBookCopyRemovedFromCirculation(bookID uuid.UUID, occurredAt time.Time) BookCopyRemovedFromCirculation

BuildBookCopyRemovedFromCirculation creates a new BookCopyRemovedFromCirculation event.

func (BookCopyRemovedFromCirculation) EventType

func (e BookCopyRemovedFromCirculation) EventType() string

EventType returns the event type identifier.

func (BookCopyRemovedFromCirculation) HasOccurredAt

func (e BookCopyRemovedFromCirculation) HasOccurredAt() time.Time

HasOccurredAt returns when this event occurred.

type BookCopyReturnedByReader

type BookCopyReturnedByReader struct {
	BookID     BookIDString
	ReaderID   ReaderIDString
	OccurredAt OccurredAtTS
}

BookCopyReturnedByReader represents when a book copy is returned by a reader.

func BuildBookCopyReturnedFromReader

func BuildBookCopyReturnedFromReader(bookID uuid.UUID, readerID uuid.UUID, occurredAt time.Time) BookCopyReturnedByReader

BuildBookCopyReturnedFromReader creates a new BookCopyReturnedByReader event.

func (BookCopyReturnedByReader) EventType

func (e BookCopyReturnedByReader) EventType() string

EventType returns the event type identifier.

func (BookCopyReturnedByReader) HasOccurredAt

func (e BookCopyReturnedByReader) HasOccurredAt() time.Time

HasOccurredAt returns when this event occurred.

type BookIDString

type BookIDString = string

BookIDString represents a book identifier.

type DomainEvent

type DomainEvent interface {
	// EventType returns the string identifier for this event type.
	EventType() string
	// HasOccurredAt returns when this event occurred.
	HasOccurredAt() time.Time
}

DomainEvent represents a business event that has occurred in the domain.

type DomainEvents

type DomainEvents = []DomainEvent

DomainEvents is a slice of DomainEvent instances.

type ISBNString

type ISBNString = string

ISBNString represents an ISBN identifier.

type OccurredAtTS

type OccurredAtTS = time.Time

OccurredAtTS represents when an event occurred.

func ToOccurredAt

func ToOccurredAt(t time.Time) OccurredAtTS

ToOccurredAt converts a time to OccurredAtTS with UTC normalization and microsecond precision.

type ProducedNewEventToAppendBool

type ProducedNewEventToAppendBool = bool

ProducedNewEventToAppendBool indicates whether a new event has been produced and is ready to be appended.

type ReaderIDString

type ReaderIDString = string

ReaderIDString represents a reader identifier.

type SomethingHasHappened

type SomethingHasHappened struct {
	ID               string
	SomeInformation  string
	OccurredAt       OccurredAtTS
	DynamicEventType string
}

SomethingHasHappened represents a generic event with a dynamic event type.

func BuildSomethingHasHappened

func BuildSomethingHasHappened(
	id string,
	someInformation string,
	occurredAt time.Time,
	dynamicEventType string,
) SomethingHasHappened

BuildSomethingHasHappened creates a new SomethingHasHappened event with dynamic type.

func (SomethingHasHappened) EventType

func (e SomethingHasHappened) EventType() string

EventType returns the dynamic event type identifier.

func (SomethingHasHappened) HasOccurredAt

func (e SomethingHasHappened) HasOccurredAt() time.Time

HasOccurredAt returns when this event occurred.