"id" field of embedded document is mapped to "_id" [DATAMONGO-524]

[spring-projects-issues]

Simon opened DATAMONGO-524 and commented

I expected that the mapper only maps fields named id in top level documents to the _id as it is the convention for mongodb. Currently even id fields of embedded documents are mapped to _id which should not be the case (not needed). Any reasons for that or am i missing something here?

---

Affects: 1.0.4

0 votes, 5 watchers

[spring-projects-issues]

Simon commented

Adding the @Field("id") on the "id" field in the embedded document also does not affect this mapping

[spring-projects-issues]

Oliver Drotbohm commented

Good point. We've been discussing this internally as well and have been on the consistency side of things (treat all id fields the same) so far. The tricky part here is that classes that might be used for top level documents might also be used as nested documents as well. If we treat them differently depending on context the DBObject object would look different as well. We were wondering whether this might cause issues or problems in some regard.

I'll keep this ticket around here to see what further feedback we get

[spring-projects-issues]

Lars Hvile commented

Also keep in mind that projects out there are depending on this bug/feature by now.. If you change this you'll break both indexes & queries in my project at least..

[spring-projects-issues]

JeremyTwiggs commented

I see this is a very old ticket, but I thought I add a note about my use case.

I use spring-boot-starter-data-mongodb-reactive to subscribe to the mongodb change stream.

To save having to duplicate and maintain various data models, I simply deserialise my documents into a Map<String, Object> and sent them on to a RabbitMQ exchange from there.

I was aware that the root document id would need modifying from '_id' to 'id', but got caught out by the case where this also happens for nested documents.

I've updated my code to handle nested documents, but if the current behaviour is changed then myself and anyone else doing likewise will be impacted

[spring-projects-issues]

Christoph Strobl commented

The issue has been resolved in the past few years. Works as designed on current master (3.0).

class Person {
	@Id String id;
	String name;
	Address address;
}

class Address {

	@Field("id")
	String id;
	String city;
}

is stored as

{
  "_id": {
    "$oid": "5e5900a07231bb411c908127"
  },
  "name": "batman",
  "address": {
    "id": "id-1",
    "city": "Gotham"
  },
  "_class": "org.springframework.data.mongodb.triage.Datamongo524$Person"
}