EmberJS：無法獲得兩個級別的hasMany數組的長度

Question

我試圖創建一個計算屬性，讓我得到所有頁面長度的總和。

但我不知道如何訪問一個孩子，所以我可以得到那個孩子的孩子。

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')[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

這裏是你如何傳播的陣列中可以訪問的第一個對象的例如：

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') 
}); 

，但我想你想在這裏獲得的總頁數。 所以，這裏是一個例子，如何進行迭代的利差和總結的的頁數：

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：看屬性依賴我通過property聲明。由於ComputedProperty依賴於這些路徑，因此您需要在那裏聲明它們。

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 
    } 

});