How to make trait refresh with property changes?

[wyxcoder]

I define trait and link to prop like

    model: {
      defaults: {  
        droppable: false,
        item_type: 'latestnews',
        item_template: '',
        traits: [
          { label: 'Item type', name: 'item_type', type: 'select', changeProp: 1,
            options: config['item_types']
          },
          { label: 'Template', name: 'item_template', type: 'text', changeProp: 1, },
        ],
      },
    },

and in view， I want to fill the trait item_template according to what user pick in the item_type dropdown. But it seems the item_template trait only get filled in init, not refresh after.

    view: defaultView.extend({
      init({ el, model }) {
        var updateHtml=()=> {
          var item_type = model.attributes.item_type;
          for(var i=0;i<config['item_types'].length; i++){
            if(config['item_types'][i]['id']==item_type){
               var template = config['item_types'][i]['template'];
               model.attributes.item_template=template;
               //var t=this.model.getTrait('item_template');
               //if(t)
               //  t.set('value', template);
            }
          }
          this.updateScript();
        };

[artf]

You can use updateTrait