Ember computed properties with arguments

Question

I was wondering if it was possible to add arguments to a computed properties. So far, everything I tried resulted in errors and found nothing on the subject. I want to build a URL using a value that is not included in my model.

I'm looking for something that would look like this :

// App.js
App.Image = DS.Model.extend({
    image_path_sh: DS.attr(), // image.jpg
    image_size_nm: DS.attr(), // 234234
    image_alt_sh: DS.attr(), // My image
    image_abs_url: function(width, height) {
        return "http://localhost/images/" + this.get('image_path_sh') + "/" + width "x" + height
    }.property('image_path_sh')
});

// index.html
// I know this doesn't work, but I'd like to have something that easy to use
{{#each image}}
    <img src="{{image_abs_url 250 250}}" alt="{{image_alt_sh}}" />
{{/each}}

My server will return an image that is resized. I don't want to put that in my database because these are not fixed value.

Answer 1

A computed property shouldn't rely on parameters, it breaks the caching paradigm, that's precisely what helpers and methods are for.

v3.2 https://guides.emberjs.com/release/templates/writing-helpers/

import { helper } from '@ember/component/helper';

export function formatCurrency([value, ...rest]) {
  let dollars = Math.floor(value / 100);
  let cents = value % 100;
  let sign = '$';

  if (cents.toString().length === 1) { cents = '0' + cents; }
  return `${sign}${dollars}.${cents}`;
}

export default helper(formatCurrency);

Global non-import versions of Ember

Ember.Handlebars.helper('img', function(prop, height, width, options) {
  return new Handlebars.SafeString('<div style="height:' + height +'px;width:'+ width +'px;background-color:' + prop + '">' + prop + '</div>');
});

http://emberjs.jsbin.com/IgUFaTAk/1/edit