Spring Boot Mongo update nested array of documents - spring-boot

Question

I'm trying to set an attribute of a document inside an array to uppercase.
This is a document example
{
"_id": ObjectId("5e786a078bc3b3333627341e"),
"test": [
{
"itemName": "alpha305102992",
"itemNumber": ""
},
{
"itemName": "beta305102630",
"itemNumber": "P5000"
},
{
"itemName": "gamma305102633 ",
"itemNumber": ""
}]
}
I already tried a lot of thing.
private void NameElementsToUpper() {
AggregationUpdate update = AggregationUpdate.update();
//This one does not work
update.set("test.itemName").toValue(StringOperators.valueOf(test.itemName).toUpper());
//This one also
update.set(SetOperation.set("test.$[].itemName").withValueOfExpression("test.#this.itemName"));
//And every variant in between these two.
// ...
Query query = new Query();
UpdateResult result = mongoTemplate.updateMulti(query, update, aClass.class);
log.info("updated {} records", result.getModifiedCount());
}
I see that Fields class in spring data is hooking into the "$" char and behaving special if you mention it. Do not seem to find the correct documentation.
EDIT: Following update seems to work but I do not seem to get it translated into spring-batch-mongo code
db.collection.update({},
[
{
$set: {
"test": {
$map: {
input: "$test",
in: {
$mergeObjects: [
"$$this",
{
itemName: {
$toUpper: "$$this.itemName"
}
}
]
}
}
}
}
}
])
Any solutions?
Thanks!

Answer 1

For now I'm using which does what i need. But a spring data way would be cleaner.
mongoTemplate.getDb().getCollection(mongoTemplate.getCollectionName(Application.class)).updateMany(
new BasicDBObject(),
Collections.singletonList(BasicDBObject.parse("""
{
$set: {
"test": {
$map: {
input: "$test",
in: {
$mergeObjects: [
"$$this",
{
itemName: { $toUpper: "$$this.itemName" }
}
]
}
}
}
}
}
"""))
);