Update query for MongoDB in Node.js

Question

How would you go about updating the 'status' attribute of the product "car" having a status of 0, to 1, in the purchases array of the following MongoDB Document.

MongoDB Document::

{
    "local": {
        "Name": "Rio",
        "Income": 300000,
        "purchases": [{
                "prod": "car",
                "status": 1
            },
            {
                "prod": "bike",
                "status": 0
            },
            {
                "prod": "car",
                "status": 0
            }
        ]
    }
}

Ashh · Accepted Answer · 2018-07-18 12:23:33Z

2

You need to use $ positional operator with $elemMatch operator

The positional $ operator identifies an element in an array to update without explicitly specifying the position of the element in the array.

db.collection.update(
  { "local.purchases": { "$elemMatch": { "prod": "car", "status": 0 }}},
  { "$set": { "local.purchases.$.status": 1 }}
)

edited Jul 18, 2018 at 12:23

answered Jul 18, 2018 at 10:01

Ashh

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2 Comments

alfheimrShiven Over a year ago

Thanks for the quick reply @anthony. Would explain me why we use that $ sign ?

s7vr Over a year ago

@AnthonyWinzlet Your answer is incorrect. It updates the status for bike not car. You've to use $elemMatch.

s7vr · Accepted Answer · 2018-07-18 10:40:59Z

1

You need to use $elemMatch to match the array element on both criteria.

db.colname.update(
  {"local.purchases":{"$elemMatch":{"prod":"car", "status":0}}},
  {"$set":{"local.purchases.$.status":1}}
)

answered Jul 18, 2018 at 10:40

s7vr

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Comments

Siddharth Sogani · Accepted Answer · 2018-07-18 10:13:05Z

0

The query will be :- db.sample.update({"local.purchases.status": 0}, {$set : {"local.purchases.$.status" : 1} });

Explanation:- Here you will have to use $ operator to reference those purchases which are matched by the find query in the first argument fo the update function. Hope it helps.

answered Jul 18, 2018 at 10:13

Siddharth Sogani

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