restOfStoreWithNormalization.js

function subjectsReducer(state = initialSubjectsState(), action = {}){
    switch(action.type){
        case LOAD_SUBJECTS_RESULTS:
            return Object.assign({}, state, { list: subjectsToHash(action.subjects) });
        case EDIT_SUBJECT:
            var editingSubject = state.list[action._id],
                newSubjectParent,
                eligibleParents = flattenedSubjects(state.list).filter(s => s._id !== action._id && (!new RegExp(`,${action._id},`).test(s.path)));

            if (editingSubject.path == null){
                newSubjectParent = null;
            } else {
                let hierarchy = editingSubject.path.split(',');
                newSubjectParent = hierarchy[hierarchy.length - 2];
            }

            return Object.assign({}, state, { editSubjectsPacket: Object.assign({}, state.editSubjectsPacket, { newSubjectName: editingSubject.name, newSubjectParent, editingSubject, eligibleParents }) });
        case UPDATE_SUBJECT_RESULTS:
            let changedSubjects = subjectsToHash(action.affectedSubjects);
            return Object.assign({}, state, { list: Object.assign({}, state.list, changedSubjects) });
    }
    return state;
}

function subjectsToHash(subjects){
    let hash = {};
    subjects.forEach(s => hash[s._id] = s);
    return hash;
}

function flattenedSubjects(subjects){
    return Object.keys(subjects).map(k => subjects[k]);
}