// Save appends all events in the event stream to the database.
func (s *EventStore) Save(events []eh.Event, originalVersion int) error {
if len(events) == 0 {
return eh.ErrNoEventsToAppend
}
// Build all event records, with incrementing versions starting from the
// original aggregate version.
eventRecords := make([]*eventRecord, len(events))
aggregateID := events[0].AggregateID()
for i, event := range events {
// Only accept events belonging to the same aggregate.
if event.AggregateID() != aggregateID {
return ErrInvalidEvent
}
// Marshal event payload.
payload, err := dynamodbattribute.MarshalMap(event)
if err != nil {
// return ErrCouldNotMarshalEvent
return err
}
// Create the event record with current version and timestamp.
eventRecords[i] = &eventRecord{
AggregateID: event.AggregateID().String(),
Version: 1 + originalVersion + i,
Timestamp: time.Now(),
EventType: event.EventType(),
Payload: payload,
}
}
// TODO: Implement atomic version counter for the aggregate.
// TODO: Batch write all events.
for _, record := range eventRecords {
// Marshal and store the event record.
item, err := dynamodbattribute.MarshalMap(record)
if err != nil {
return err
}
putParams := &dynamodb.PutItemInput{
TableName: aws.String(s.config.Table),
ConditionExpression: aws.String("attribute_not_exists(AggregateID) AND attribute_not_exists(Version)"),
Item: item,
}
if _, err = s.service.PutItem(putParams); err != nil {
if err, ok := err.(awserr.RequestFailure); ok && err.Code() == "ConditionalCheckFailedException" {
return ErrCouldNotSaveAggregate
}
return err
}
}
return nil
}
// SaveUser creates or updates a user. Upon creation, users are assigned a unique ID.
func (db *DynamoDB) SaveUser(u *models.User) error {
if u.ID == "" {
id, err := shortid.ID(64)
if err != nil {
return err
}
u.ID = id
}
item, err := dynamodbattribute.MarshalMap(u)
if err != nil {
return err
}
_, err = db.DB.PutItem(&dynamodb.PutItemInput{
TableName: aws.String("users"),
Item: item,
})
if err != nil {
return err
}
return nil
}