为什么我不能将字段添加到JS对象？

Question

我使用Sequelize ORM为MySQL编程节点。我需要为Sequelize在查询上返回的对象添加一个新字段，但似乎不起作用。

Category.find({ 
    where: { id: req.params.id }, 
    include: [Item] 
}).success(function(category) { 
    var items = category.items; 
    var ci = category.items.map(function(item) { return item.id; }); 
    delete category.items; // this works 
    category.item_ids = ci; // this doesn't 
    // category['item_ids'] = ci; // this doesn't work as well 

    res.send({ 
    category: category, 
    items: items 
    }); 
}); 

Object.isExtensible上category对象返回true，但我想不出如何实际进行扩展

Answer 1

试试这个：

.success(function(category) { 
    category = category.toJSON(); // convert to a simple JS object 
    ... 
    category.item_ids = ci; 
    ... 
    res.render(...); 
}); 

Answer 2

您可以添加一个计算的属性：

http://www.sequelizejs.com/documentation#models-expansion