Where and how to include Ember model functions

问题

I am working on a simple Ember app that shows ID's for list elements. The ID's are computed with simple functions based on the element sequence (and some other simple factors). For example:

<div class="content-id element">[ELEMENT ID]</div>
<div class="content-name">{{element.name}}</div>

I don't want to hardcode the element id's into the JSON object, but rather compute them in a simple function. Would it be best to place this function in the route object or in the component? What's the syntax?

Thank you.

回答1:

If you want to compute something based only on model properties, you should use a computed property. In following example I define a computed property citiesString:

import DS from 'ember-data';
import Ember from 'ember';

export default DS.Model.extend({
  name: DS.attr('string'),
  cities: DS.hasMany('city', { async: false }),

  citiesString: Ember.computed('cities', function () {
    var cities = [];
    this.get('cities').forEach(function (item, index, enumerable) {
      cities.push(item.get('name'));
    }, this);

    return cities.join(', ');
  })
});

You can use computed property like any other:

{{#each elements as |element index|}}
  {{element.citiesString}}
{{/each}}

If you want to use element's index (if I understand "element sequence" right), I can't think out other way than writing a helper, pass to it element, index, and return ID. Example of helper:

//app/helpers/my-helper.js
import Ember from 'ember';

export default Ember.Handlebars.makeBoundHelper(function (element, index) {
  return index; //do something useful instead of this
});

How to use it:

{{#each elements as |element index|}}
  {{my-helper element index}}
{{/each}}

You should keep in mind that index can change (as can order of element in array) and different users may see different ID for the same element.

来源：https://stackoverflow.com/questions/32235795/where-and-how-to-include-ember-model-functions

标签

ember.js

model