way to update multiple documents with different values

Question

I have the following documents:

[{
  \"_id\":1,
  \"name\":\"john\",
  \"position\":1
},
 {\"_id\":2,
  \"name\":\"bob\",
  \"position\":2
},
 {\"_id\":3,
           


        

Answer 1

From mongodb 4.2 you can do using pipeline in update using $set operator

there are many ways possible now due to many operators in aggregation pipeline though I am providing one of them

    exports.updateDisplayOrder = async keyValPairArr => {
    try {
        let data = await ContestModel.collection.update(
            { _id: { $in: keyValPairArr.map(o => o.id) } },
            [{
                $set: {
                    displayOrder: {
                        $let: {
                            vars: { obj: { $arrayElemAt: [{ $filter: { input: keyValPairArr, as: "kvpa", cond: { $eq: ["$$kvpa.id", "$_id"] } } }, 0] } },
                            in:"$$obj.displayOrder"
                        
                        }
                    }
                }
            }],
            { runValidators: true, multi: true }
        )

        return data;
    } catch (error) {
        throw error;
    }
   }

example key val pair is [{"id":"5e7643d436963c21f14582ee","displayOrder":9}, {"id":"5e7643e736963c21f14582ef","displayOrder":4}]

Answer 2

Since MongoDB 4.2 update can accept aggregation pipeline as second argument, allowing modification of multiple documents based on their data.

See https://docs.mongodb.com/manual/reference/method/db.collection.update/#modify-a-field-using-the-values-of-the-other-fields-in-the-document

Excerpt from documentation:

Modify a Field Using the Values of the Other Fields in the Document

Create a members collection with the following documents:

db.members.insertMany([
  { "_id" : 1, "member" : "abc123", "status" : "A", "points" : 2, "misc1" : "note to self: confirm status", "misc2" : "Need to activate", "lastUpdate" : ISODate("2019-01-01T00:00:00Z") },
  { "_id" : 2, "member" : "xyz123", "status" : "A", "points" : 60, "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment", "lastUpdate" : ISODate("2019-01-01T00:00:00Z") }
])

Assume that instead of separate misc1 and misc2 fields, you want to gather these into a new comments field. The following update operation uses an aggregation pipeline to:

• add the new comments field and set the lastUpdate field.
• remove the misc1 and misc2 fields for all documents in the collection.

db.members.update(
  { },
  [
     { $set: { status: "Modified", comments: [ "$misc1", "$misc2" ], lastUpdate: "$$NOW" } },
     { $unset: [ "misc1", "misc2" ] }
  ],
  { multi: true }
)

Answer 3

You can use db.collection.bulkWrite() to perform multiple operations in bulk. It has been available since 3.2.

It is possible to perform operations out of order to increase performance.

Answer 4

You can not update two documents at once with a MongoDB query. You will always have to do that in two queries. You can of course set a value of a field to the same value, or increment with the same number, but you can not do two distinct updates in MongoDB with the same query.