Mongoose 如何将_id 自动添加到集合项中数组中的对象？

Question

i have a mongo collection that looks like this:

{
    name: string
    _id: (auto set)
    items: array[
        name: string
        url: string
        items: array[
            {
                name: string,
                url: string,
                items: []
            }
        ]
    ]
}

I'm using findByIdAndUpdate (with mongoose) to add an item into the items array:

Menu.findByIdAndUpdate(
    req.body.parentid, 
    {
        $push: {
            items: {
                name: req.body.item.name, 
                url: req.body.item.url,
                items: []
            }
        }
    },
    {
        safe: true, 
        upsert: true, 
        new: true
    },
    function(err, model) {
        if (err !== null) {
            console.log(err);
        }
    }
);

This works fine, but it does not add an _id to each object inserted into the items array. And i really need an id for each one.

I'm guessing it comes from the method used, findByIdAndUpdate as it looks more like an update rather than an insert. If my thinking is correct.

Using mongodb 3.2.10 and mongoose 4.7.6.

Any help would be really appreciated. Thanks.

EDIT: the _id: (auto set) is not real, it's being automatically added via mongo. But just at the top level objects.

Answer 1

Found the solution in this thread: mongoDB : Creating An ObjectId For Each New Child Added To The Array Field

basically, added

var ObjectID = require('mongodb').ObjectID;

and then forcing the creation:

$push: {
    items: {
        _id: new ObjectID(),
        name: req.body.item.name, 
        url: req.body.item.url,
        items: []
    }
}

Answer 2

你不需要在mongoose架构中sepcify _id :(自动设置）它会自动为每个文档添加唯一的_id。

Answer 3

if you don't define _id in Schema, mongoose automatically add a _id to array item. for example:

const countrySchema = new Schema({
  name: {
    type: String
  },
  cities: [
    {
      // don't define _id here.
      name: String
    }
  ],
});

now when you insert a row, the result is something like this:

{name: 'Iran', cities: [{_id: 6202902b45f0d858ac141537,name: 'Tabriz'}]}