javascript对象数组未更改

Question

此代码用于从MongoDB获取数据并将"_id"元素更改为"id元素".但我发现对象数组没有改变.

router.get('/loadList', (req,res) => {
Post.find({}, (err, list) => {          //fetching data to list
    if(err) {
        return res.json({success : false});
    } else {
        let new_list;   

        //change _id to id
        new_list = list.map((obj) => {
            obj.id = obj._id;
            delete obj._id;
            return obj;
        }); 

        console.log(new_list);

     /* 
     // _id is still here and id is not created
     [{_id: '58e65b2d1545fe14dcb7aac5',
     title: 'asdfassafasdf',
     content: 'dfasfdasdf',
     time: '2017-04-06T15:13:49.516Z',
     writer: { _id: '100975133897189074897', displayName: 'Kiyeop Yang' },
     coords: { y: '310.3999786376953', x: '139' },
     __v: 0 } ] 
     */

但是这段代码就像我想要的那样

        let list2 = JSON.parse(JSON.stringify(list));
        new_list = list2.map((obj) => {
            obj.id = obj._id;
            delete obj._id;
            return obj;
        });
        console.log(new_list);
  /*
  // _id is deleted and id is created
   { title: 'asdfassafasdf',
     content: 'dfasfdasdf',
     time: '2017-04-06T15:13:49.516Z',
     writer: { _id: '100975133897189074897', displayName: 'Kiyeop Yang' },
     coords: { y: '310.3999786376953', x: '139' },
     __v: 0,
     id: '58e65b2d1545fe14dcb7aac5' } ]
 */

        return res.json({
            success : true,
            list
        });
    }
});

});

我认为这与深层和浅层复制有关.但我不知道是什么原因引起的.

谢谢

Answer 1

那是因为Post.find根据创建的架构返回猫鼬对象。您正在寻找的是toObject返回纯 javascript 对象的函数。因此，在回调调用中，list.toObject(); 您可以toObject在 mongoose 文档中阅读有关函数的更多信息：http://mongoosejs.com/docs/api.html#document_Document-toObject

或者，您可以使用lean选项，它会告诉mongoose返回纯javascript对象： http://mongoosejs.com/docs/api.html#query_Query-lean