Example for my iDDD with Go blog article series at https://medium.com/@TonyBologni

ConfirmEmailAddress.go

package customer

import (
    "github.com/AntonStoeckl/go-iddd/service/customeraccounts/application/domain"
    "github.com/AntonStoeckl/go-iddd/service/shared/es"
    "github.com/cockroachdb/errors"
)

func ConfirmEmailAddress(eventStream es.EventStream, command domain.ConfirmCustomerEmailAddress) (es.RecordedEvents, error) {
    customer := buildCurrentStateFrom(eventStream)

    if err := assertNotDeleted(customer); err != nil {
        return nil, errors.Wrap(err, "confirmEmailAddress")
    }

    if err := assertMatchingConfirmationHash(customer.emailAddressConfirmationHash, command.ConfirmationHash()); err != nil {
        event := domain.BuildCustomerEmailAddressConfirmationFailed(
            customer.id,
            customer.emailAddress,
            command.ConfirmationHash(),
            err,
            customer.currentStreamVersion+1,
        )

        return es.RecordedEvents{event}, nil
    }

    if customer.isEmailAddressConfirmed {
        return nil, nil
    }

    event := domain.BuildCustomerEmailAddressConfirmed(
        customer.id,
        customer.emailAddress,
        customer.currentStreamVersion+1,
    )

    return es.RecordedEvents{event}, nil
}