Mongodb: How to add unique value to each element in array?

Question

I'm a new user of mongodb and I have a model like below. For update list data, I have to specify the element in an array. So I think I need to store a unique value for each element. Because list.name and list.price are variable data.

So are there any good ways to create an unique id in mongodb? Or should I create unique ids by myself?

{
   name: 'AAA',
   list: [
     {name: 'HOGE', price: 10, id: 'XXXXXXXXXX'}, // way to add id
     {name: 'FUGA', price: 12, id: 'YYYYYYYYYY'}  // way to add id
   ]
}

PaulShovan · Accepted Answer · 2016-01-02 16:04:02Z

1

Mongodb creates unique id only for documents. There is no better way for list or array elements. So, you should create Unique ids yourself.

Add keep in mind that, While updating your list use $addToSet. For more information of $addToSet follow this documentation

answered Jan 2, 2016 at 16:04

PaulShovan

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britishgreenworm · Accepted Answer · 2016-01-03 06:14:27Z

0

use ObjectId() on your id field, so like..

db.test.update({name: "AAA"}, { $push: { list: {_id : ObjectId(), name: "dingles", price: 21} }});

reference: https://docs.mongodb.org/v3.0/reference/object-id/

answered Jan 3, 2016 at 6:14

britishgreenworm

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Shashank Mistry · Accepted Answer · 2022-02-18 11:33:19Z

0

whoever is seeing this in 2022, mongodb creates unique ids automatically we just have to provide schema for that particular array. like,

 _id : {
        type: String
    },
    list: {
        type: [{
            Name : {
                type: String
            },
            price : {
                type: String
            }
        }]
    }

this schema will generate auto id for all elements added into array but below example will not create it.

 _id : {
        type: String
    },
    list: {
        type: Array
    }

answered Feb 18, 2022 at 11:33

Shashank Mistry

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