how to add values using mongodb aggregation

Question

is there any way to add values via aggregation like db.insert_one

x = db.aggregate([{
    "$addFields": {
        "chat_id": -10013345566,
    }
}])

i tried this but this code return nothing and values are not updated

i wanna add the values via aggregation cuz aggregation is way faster than others

sample document :

    {"_id": 123 , "chat_id" : 125}
    {"_id": 234, "chat_id" : 1325}
    {"_id": 1323 , "chat_id" : 335}

expected output :

alternative to db.insert_one() in mongodb aggregation

Share a sample document and expected output

hhharsha36
– hhharsha36

2021-12-05 06:25:11 +00:00
Commented Dec 5, 2021 at 6:25 — hhharsha36
– hhharsha36, Commented Dec 5, 2021 at 6:25
@hhharsha36 check edits

Yato
– Yato

2021-12-05 07:54:44 +00:00
Commented Dec 5, 2021 at 7:54 — Yato
– Yato, Commented Dec 5, 2021 at 7:54

hhharsha36 · Accepted Answer · 2021-12-05 14:18:20Z

1

You have to make use of $merge stage to save output of the aggregation to the collection.

Note: Be very very careful when you use $merge stage as you can accidentally replace the entire document in your collection. Go through the complete documentation of this stage before using it.

db.collection.aggregate([
  {
    "$match": {
      "_id": 123
    }
  },
  {
    "$addFields": {
      "chat_id": -10013345566,
      
    }
  },
  {
    "$merge": {
      "into": "collection",  // <- Collection Name
      "on": "_id",  // <- Merge operation match key
      "whenMatched": "merge"  // <- Operation to perform when matched
    }
  },
])

Mongo Playground Sample Execution

answered Dec 5, 2021 at 14:18

hhharsha36

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2 Comments

Yato Over a year ago

but i want to update only single value tho

hhharsha36 Over a year ago

In that case you have to make sure that only that single field and _id field are returned before the last stage and perform $merge with whenMatched: "merge" option. Regardless, what you are looking for can be achieved only by $merge stage.

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