MongoDB 3.2 Update Field name in embedded array - mongodb

Question

Im trying to do a i migration in my MongoDB. I have updated a Field from Content -> StringContent. Now I want to update all records that exists with the new Field name.
This is how a document looks like.
{
"_id" : "c4af0b19-4c78-4e58-bbe5-ac9e5cce2c3f",
"Type" : "Onboarding",
"Cards" : [
{
"_id" : LUUID("3f328a1c-658d-ee4e-8f06-561760eb5be5"),
"Width" : 1,
"Title" : "",
"Type" : "Freetext",
"Description" : "",
"Content" : "This is a test" // -> "StringContent" : "This is a Test"
},
{
"_id" : LUUID("2f328a1c-658d-ee4e-8f06-561760eb5be5"),
"Width" : 1,
"Title" : "",
"Type" : "Freetext",
"Description" : "",
"Content" : "This is another test" //-> "StringContent" : "This is another Test"
}
],
"DocumentType" : "Template",
"History" : [
{
"Date" : ISODate("2017-07-13T12:03:01.620Z"),
"ByUserId" : LUUID("4ecaa6ca-2ce6-f84c-81f3-28f8f0256e6e")
}
],
"Name" : "Default Template"
}
I have created this script:
var bulk = db.getCollection('OnboardingPortal').initializeOrderedBulkOp(),
count = 0;
db.getCollection('OnboardingPortal').find({"DocumentType": "Template"}).
forEach(function(doc) {
doc.Cards.forEach(function(card) {
if(card.hasOwnProperty("Content")){
print(card);
bulk.find({"_id": doc._id, "Cards._id": card._id}).update(
{
$set: {"Cards.$.StringContent": card.Content}
});
bulk.find({"_id": doc._id, "Cards._id": card._id}).update(
{
$unset: {"Cards.$.Content": 1}
});
count += 2;
if(count % 500 == 0) {
bulk.execute();
bulk = db.getCollection('OnboardingPortal').initializeOrderedBulkOp();
}
}
});
});
if ( count % 500 !== 0 ){
bulk.execute();
}
This Does not update anything, but if I change bulk.operations -> to explicit set index on array like this, it will do the job. but only for one card :
bulk.find({"_id": doc._id, "Cards.1._id": card._id}).update(
{
$set: {"Cards.1.StringContent": card.Content}
});
bulk.find({"_id": doc._id, "Cards.1._id": card._id}).update(
{
$unset: {"Cards.1.Content": 1}
});
What am i missing in my script so this can iterates over several documents and change Content-> StringContent in each Card. ?
EDIT
I have added a bulk.getOperations(); in my script. this is what it returns. Should it not have replaced $ with index ?
/* 1 */
[
{
"originalZeroIndex" : 0.0,
"batchType" : 2.0,
"operations" : [
{
"q" : {
"_id" : "c4af0b19-4c78-4e58-bbe5-ac9e5cce2c3f",
"Cards._id" : "1c8a323f-8d65-4eee-8f06-561760eb5be5"
},
"u" : {
"$set" : {
"Cards.$.StringContent" : "This is a cool test"
}
},
"multi" : false,
"upsert" : false
},
{
"q" : {
"_id" : "c4af0b19-4c78-4e58-bbe5-ac9e5cce2c3f",
"Cards._id" : "1c8a323f-8d65-4eee-8f06-561760eb5be5"
},
"u" : {
"$unset" : {
"Cards.$.Content" : 1.0
}
},
"multi" : false,
"upsert" : false
},
{
"q" : {
"_id" : "c4af0b19-4c78-4e58-bbe5-ac9e5cce2c3f",
"Cards._id" : "1c8a322f-8d65-4eee-8f06-561760eb5be5"
},
"u" : {
"$set" : {
"Cards.$.StringContent" : "This is a test"
}
},
"multi" : false,
"upsert" : false
},
{
"q" : {
"_id" : "c4af0b19-4c78-4e58-bbe5-ac9e5cce2c3f",
"Cards._id" : "1c8a322f-8d65-4eee-8f06-561760eb5be5"
},
"u" : {
"$unset" : {
"Cards.$.Content" : 1.0
}
},
"multi" : false,
"upsert" : false
}
]
}
]