Update a field or create it if it is not present in mongoDb

I have a collection named users and it already has many documents inside it but some documents are missing the field name newUnreadMessage of type boolean . I want to update this field to false if it is already present . And if it is not present i want to create this field inside that respective document and set its value to false

I tried doing

User.find({ builder: builderId }).find({ _id: data.userId }).update({ newUnreadMessage: false }, { $set: { "newUnreadMessage": false } })

I dont know why but it is not creating a new field in case it is not present . I am new to MongoDb please help me out

You will need to add the option "{ multi: true }" to your update operation to be able to update the multiple documents you need to , check the update command syntax here

playground example

db.collection.update({
  builder: "b1"
},
{
  $set: {
   "newUnreadMessage": false
 }
},
{
  multi: true
})

Indeed also as @Yong Shun mentioned if your search criteria match newUnreadMessage: false , you will not be able to modify documents missing the key newUnreadMesage ...