EmberJS：无法获取的hasMany数组的长度两级下来(EmberJS: Unable to g

我试着去创建一个计算的属性，让我所有页面的长度的总和。

但我无法弄清楚如何访问一个孩子，所以我可以得到这个孩子的孩子的。

App.Document = DS.Model.extend({
    name: DS.attr('string'),
    spreads: DS.hasMany('App.Spread'),

    pagesCount: function() {
                // Here is where i go wrong, i can get the length of spreads, but not access a spread to get the page length.
                var spreadsLength = this.get('spreads.length');
                var firstSpread = this.get('spreads')[0];
                return firstSpread.get('pages.length');
    }.property('spreads')
});

App.Spread = DS.Model.extend({
    document: DS.belongsTo('App.Document'),
    pages: DS.hasMany('App.Page')
})

App.Page = DS.Model.extend({
    spread: DS.belongsTo('App.Spread'),
    page_name: DS.attr('string'),
    page_items: DS.hasMany('DS.PageItem')
})

Answer 1:

这里是你如何可以访问利差的数组中的第一个对象的例子：

App.Document = DS.Model.extend({
    name: DS.attr('string'),
    spreads: DS.hasMany('App.Spread'),

    pagesCount: function() {
        // Here is where i go wrong, i can get the length of spreads, but not access a spread to get the page length.
        var spreadsLength = this.get('spreads.length');

        var firstSpread = this.get('spreads').objectAt(0);
        // var firstSpread = this.get('spreads.firstObject'); // elegant way to first Object

        return firstSpread.get('pages.length');
    }.property('spreads.firstObject.pages.length')
});

不过，我想你想在这里获得的总页数。 所以，这里是一个例子，如何进行迭代的利差，总结页数 ：

App.Document = DS.Model.extend({
    name: DS.attr('string'),
    spreads: DS.hasMany('App.Spread'),

    pagesCount: function() {
        // Here is where i go wrong, i can get the length of spreads, but not access a spread to get the page length.
        var spreadsLength = this.get('spreads.length');
        var ret = 0;
        this.get("spreads").forEach(function(spread)){
            ret += spread.get('pages.length');
        }
        return ret;
    }.property('spreads.@each.pages.length')
});

注：看看属性依赖我通过申报property 。由于ComputedProperty依赖于这些路径，你需要有申报。

Answer 2:

App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('st    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && fields.lastNameenter code here
  }

});ring'),
  phone: D    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields)    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && fields.lastNameenter code here
  }

}); {
    return fields.firstName && fields.lastNameenter code here
  }

});
    return fields.firstName && fields.lastNameenter code here
  }

});S.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && fields.lastNameenter code here
  }

});

App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && fields.lastNameenter code here
  }

});
  phone: DS.attr('string'),
  status: DS.attr('    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && field    App.User = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  email: DS.attr('string'),
  phone: DS.attr('string'),
  status: DS.attr('string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && fields.lastNameenter code here
  }

});s.lastNameenter code here
  }

});string', { defaultValue: 'new' }),
  notes: DS.attr('string'),
//  projects: DS.hasMany("project", {async: true}),
    projectsCount: function() {
//    alert(this.get('projects'));
        return this.get('projects.length');
    }.property('id'),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName')
  }.property('firstName', 'lastName')

}),

App.User.reopenClass({

  valid: function(fields) {
    return fields.firstName && fields.lastNameenter code here
  }

});