CODEWITHSUNDEEP
arraysmongodbmongodb-queryaggregation-framework
Kingswoop
Kingswoop

Reputation: 148

How to overwrite current document mongodb

I have this aggregation command and need to overwrite the current documents;

db.collection.aggregate([
  {
        $project: {
            class: "Apples",
            imageUrl: { $substr: [ "$imageUrl", 0, { $indexOfBytes: [ "$imageUrl", "\n" ] } ] }
        }
    }
])

Collection:
{
id:...
class:"Apples"
imageUrl:"..."
}

There are multiple documents that need to be updated. this is what i currently have appended to the above command but its not working.

.forEach( doc => db.product.updateOne( { _id: doc._id }, { $set: { imageUrl: doc.imageUrl } } ) )

Thanks in advance!

Upvotes: 1

Views: 348

Answers (1)

mickl
mickl

Reputation: 49945

You can either run $out (replaces entire existing collection with aggregation result):

db.collection.aggregate([
    {
        $project: {
            class: "Apples",
            imageUrl: { $substr: [ "$imageUrl", 0, { $indexOfBytes: [ "$imageUrl", "\n" ] } ] }
        }
    },
    { $out: "collection" }
])

or new $merge operator ("merges" aggregation results with existing documents):

db.collection.aggregate([
    {
        $project: {
            class: "Apples",
            imageUrl: { $substr: [ "$imageUrl", 0, { $indexOfBytes: [ "$imageUrl", "\n" ] } ] }
        }
    },
    { $merge: { into: "collection", on: "_id", whenMatched: "replace", whenNotMatched: "insert" } }
])

Upvotes: 3

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