Using defineProperty to create a computed property that drives an Ember.Select

gistfile1.js

setupExistingParams: function(){

    Ember.defineProperty(this, 'record_phase', Ember.computed('record_workflow_segment_step_params.[]', function(key, value){
        if( this.get('step_type').toString() !== "1" ){
            return undefined;
        }

        var param = this.get('record_workflow_segment_step_params').findBy('name', 'record_phase');
        if( !Ember.isNone( value ) )
        {
            param.set('value', value);
        }

            return param.get('value').toString();
    }));

}.on('init')