Updating a set of documents from a list of key value pairs in MongoDB

To update multiple documents from a list of key-value pairs in MongoDB, use bulk operations with initializeUnorderedBulkOp() to efficiently process multiple updates in a single operation.

Syntax

var bulkUpdateValue = [{"_id": "key1", "field": "value1"}, {"_id": "key2", "field": "value2"}];
var bulkUpdate = db.collection.initializeUnorderedBulkOp();
for (var i = 0; i < bulkUpdateValue.length; i++){
    var updateItem = bulkUpdateValue[i];
    bulkUpdate.find({_id: updateItem._id}).update({$set: {field: updateItem.field}});
}
bulkUpdate.execute();

Sample Data

db.demo227.insertMany([
    {"_id": "101", "Name": "Chris"},
    {"_id": "102", "Name": "Bob"}
]);

{
  "acknowledged": true,
  "insertedIds": {
    "0": "101",
    "1": "102"
  }
}

Display all documents from the collection ?

db.demo227.find();

{ "_id" : "101", "Name" : "Chris" }
{ "_id" : "102", "Name" : "Bob" }

Example: Bulk Update from Key-Value List

Update multiple documents using a predefined list of key-value pairs ?

var bulkUpdateValue = [
    {"_id": "101", "Name": "Robert"},
    {"_id": "102", "Name": "Sam"}
];

var bulkUpdate = db.demo227.initializeUnorderedBulkOp();
var updateCounter = undefined;

for (var i = 0; i < bulkUpdateValue.length; i++){
    updateCounter = bulkUpdateValue[i];
    bulkUpdate.find({_id: updateCounter._id}).update({$set: {Name: updateCounter.Name}});
}

bulkUpdate.execute();

BulkWriteResult({
    "writeErrors" : [ ],
    "writeConcernErrors" : [ ],
    "nInserted" : 0,
    "nUpserted" : 0,
    "nMatched" : 2,
    "nModified" : 2,
    "nRemoved" : 0,
    "upserted" : [ ]
})

Verify Results

Check the updated documents ?

db.demo227.find();

{ "_id" : "101", "Name" : "Robert" }
{ "_id" : "102", "Name" : "Sam" }

Key Points

• initializeUnorderedBulkOp() creates a bulk operation for better performance with multiple updates.
• The loop iterates through the key-value list and queues each update operation.
• execute() processes all queued operations in a single database call.

Conclusion

Bulk operations with initializeUnorderedBulkOp() provide an efficient way to update multiple documents from a predefined list of key-value pairs, reducing database round trips and improving performance.