forked from andrewwebber/cqrs
/
event-source-based.go
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/
event-source-based.go
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package cqrs
import (
"code.google.com/p/go-uuid/uuid"
"reflect"
)
// EventSourced providers an interface for event sourced aggregate types
type EventSourced interface {
ID() string
SetID(string)
Version() int
SetVersion(int)
Events() []interface{}
CallEventHandler(event interface{})
}
// EventSourceBased provider a base class for aggregate times wishing to contain basis helper functionality for event sourcing
type EventSourceBased struct {
id string
version int
events []interface{}
source interface{}
handlersCache HandlersCache
}
// NewEventSourceBased constructor
func NewEventSourceBased(source interface{}) EventSourceBased {
return NewEventSourceBasedWithID(source, uuid.New())
}
// NewEventSourceBasedWithID constructor
func NewEventSourceBasedWithID(source interface{}, id string) EventSourceBased {
return EventSourceBased{id, 0, []interface{}{}, source, createHandlersCache(source)}
}
// Update should be called to change the state of an aggregate type
func (s *EventSourceBased) Update(versionedEvent interface{}) {
s.CallEventHandler(versionedEvent)
s.events = append(s.events, versionedEvent)
}
// CallEventHandler routes an event to an aggregate's event handler
func (s *EventSourceBased) CallEventHandler(event interface{}) {
eventType := reflect.TypeOf(event)
if handler, ok := s.handlersCache[eventType]; ok {
handler(s.source, event)
} else {
panic("No handler found for event type " + eventType.String())
}
}
// ID provider the aggregate's ID
func (s *EventSourceBased) ID() string {
return s.id
}
// SetID sets the aggregate's ID
func (s *EventSourceBased) SetID(id string) {
s.id = id
}
// Version provider the aggregate's Version
func (s *EventSourceBased) Version() int {
return s.version
}
// SetVersion sets the aggregate's Version
func (s *EventSourceBased) SetVersion(version int) {
s.version = version
}
// Events returns a slice of newly created events since last deserialization
func (s *EventSourceBased) Events() []interface{} {
return s.events
}