Ember-Data belongsTo / hasMany isDirty workaround. NOTE: These are used in an Ember-App-Kit application setup.

base-model.js

export default DS.Model.extend({
    modelIsDirty:   DS.attr('boolean', {default: false}),
    relationshipWatchList: [],
    relationshipWatcherSetup: function(){
        this.get('relationshipWatchList').forEach(function(item,index,enumerable){
            this.addObserver(item, this, "changeObserver");
        }, this);
    }.on('init'),

    changeObserver: function(){
        if( this.get('isDeleted') === false )
        {
            var isDirty = this.get('relationshipWatchList').any(function(item,index,enumerable){
                return this.get(item) !== this.get('_data')[item];
            }, this);
            this.set('modelIsDirty', isDirty );
        }
    }
});

extended-model.js

import BaseModel from "appkit/models/base-model";
export default BaseModel.extend({
    prop1:                      DS.belongsTo('option'),
    prop2:                      DS.belongsTo('option'),
    prop3:                      DS.belongsTo('option'),
    relationshipWatchList:      ['prop1', 'prop2', 'prop3']
});