orderRawQuery(field, direction) {
        if (field === 'email_open_rate') {
            return {
                orderByRaw: `members.email_open_rate IS NOT NULL DESC, members.email_open_rate ${direction}`
            };
        }
    }
We have to ensure consistency. If you listen on model events (e.g. `member.added`), you can expect that you always
receive all fields including relations. Otherwise you can't rely on a consistent flow. And we want to avoid
that event listeners have to re-fetch a resource. This function is used in the context of inserting
and updating resources. We won't return the relations by default for now.