Search code examples
node.jsmongodbcloud9

Add fields in all documents of a collection - MongoDB

I'm having difficulty with the syntax for adding a new field across all documents in a MongoDB collection. Any ideas where I'm going wrong?

For example, I would like to add an empty Array to all documents in a collection called 'cats':

db.cats.updateMany({}, {$set: {images: []}});

It returns the following in AWS Cloud9 command line and doesn't update in MongoDB Atlas documents:

MongoDB Enterprise **db**-shard-0:PRIMARY> db.cats.updateMany({}, {$set: {images: []}});
{ "acknowledged" : true, "matchedCount" : 0, "modifiedCount" : 0 }

I'm using MongoDB shell version v3.6.3 (however my Server version is 4.2.8)

Solution

  • You have to use empty selector, and set a multi flag to true (last param) to update all the documents

    db.getCollection('cats').update(
  {},
  { $set: {"images": []} },
  false,
  true
)