使计算属性取决于emberjs中另一个对象的所有属性 [英] Making a computed property dependent on all the properties of another object in emberjs

问题描述

是否可以使属性依赖于另一个对象的所有属性？例如：（也在jsfiddle ）：

Is it possible to make a property dependent on all the properties of another object? For example: (also in jsfiddle):

html：

<script type="text/x-handlebars" >
    {{outlet}}
</script>

<script type="text/x-handlebars" data-template-name="index">
    <p>Weapon damage: {{ input value=model.activeWeapon.damage}} </p>
    <p>Hero damage: {{ model.weaponDamagePerSecond }}</p>
</script>

javascript：

javascript:

App = Ember.Application.create({});

App.Weapon = Ember.Object.extend({
    damage: null,
    speed: null
});

App.Hero = Ember.Object.extend({
    activeWeapon: null,
    strength: null,
    weaponDamagePerSecond: function() {
      var weapon = this.get('activeWeapon');
      console.log('weapon damage:' + weapon.get('damage'));
      console.log('weapon speed:' + weapon.get('speed'));
      console.log('strength:' + this.get('strength'));
      console.log (weapon.get('damage') + this.get('strength')) * weapon.get('speed');

      return (1.0 * weapon.get('damage') + 1.0 * this.get('strength')) * weapon.get('speed');
    }.property('activeWeapon', 'strength')
    //}.property('activeWeapon.damage', 'activeWeapon.speed', 'strength')
    // the above line will make the example work, but it is a bit painful to 
    // have to specify all the attributes needed of activeWeapon.
});

App.IndexRoute = Ember.Route.extend({
    model: function() {
        return App.Hero.create({
            activeWeapon: App.Weapon.create({
                damage: 40,
                speed: 2
            }),
            strength: 8
        });
    }
});

是否可以获取 weaponDamagePerSecond 来更新当$ activeWeapon 上的任何属性更新时，必须手动指定所有属性（如在注释掉的代码中）？

Is it possible to get weaponDamagePerSecond to update when any property on activeWeapon updates, with having to specify all the properties manually (like in the commented out code)?

推荐答案

不，但编写一个观察器的观察者真的很容易，并且在更新任何时候触发您的计算属性进行更新。我不一定是推荐这个，但可以做到。

No, but it's really easy to write up an observer that watches everything and triggers your computed property to update anytime it updates. I'm not necessarily recommending this, but it can be done.

http://jsfiddle.net/5gS59/

App.Weapon = Ember.Object.extend({
    damage: null,
    speed: null,
    version: 0,
    watchingEverything: function(){
        console.log('hello');
        this.incrementProperty('version');
    }.observes('damage','speed')
});


weaponDamagePerSecond: function() {
  var weapon = this.get('activeWeapon');
  console.log('weapon damage:' + weapon.get('damage'));
  console.log('weapon speed:' + weapon.get('speed'));
  console.log('strength:' + this.get('strength'));
  console.log (weapon.get('damage') + this.get('strength')) * weapon.get('speed');

  return (1.0 * weapon.get('damage') + 1.0 * this.get('strength')) * weapon.get('speed');
}.property('activeWeapon.version', 'strength')

做一个类似的事情只是一个属性，而不是观察：

You can alternately do a similar thing with just a property and not an observes:

http://jsfiddle.net/XsuxA/1/

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