UpdateOperations embedded array - arrays

Question

I have an structure like this:
{
_id: 123,
bs: [
{
_id: 234,
cs: [
{
_id: 456,
ds : [
{
_id: 678,
emails[
"email#gmail.com"
]
}
]
}
]
}
]
}
My classes in Morphia seems like this
#Entity
public class A {
#Id
private ObjectId id;
#Embedded
private List<B> bs;
}
public class B {
private ObjectId id;
#Embedded
private List<C> cs;
}
public class C {
private ObjectId id;
#Embedded
private List<D> ds;
}
public class D {
private ObjectId id;
#Embedded
private List<String> emails;
}
What I am trying to do is insert an email inside embedded array with Morphia without retrieve all element A and use updateFirst.
This is the query I am trying execute
Query<Event> query = this.basicDAO.createQuery();
query.criteria(Mapper.ID_KEY).equal(new ObjectId(aID));
query.criteria("bs.cs.id").equal(new ObjectId(cID));
query.criteria("bs.cs.ds.id").equal(dID);
UpdateOperations<Event> updateOps = this.basicDAO.createUpdateOperations().set("bs.cs.ds.$.emails", email);
this.basicDAO.update(query, updateOps);
I also read about this post Update an item in an array that is in an array with said that
$ operator does not work "with queries that traverse nested arrays".
So I tried something like:
D d = new D(dID);
C c = new C(new ObjectId(cID));
Query<Event> query = this.basicDAO.createQuery();
query.criteria(Mapper.ID_KEY).equal(new ObjectId(aID));
query.field("bs.cs").hasThisElement(c);
query.field("bs.cs.ds").hasThisElement(d);
UpdateOperations<Event> updateOps = this.basicDAO.createUpdateOperations().set("bs.cs.ds.emails", email);
this.basicDAO.update(query, updateOps);
However it still doesn't work. Any idea how solve this? The error message that I receive is cannot use the part ... to transverse the element

Answer 1

Based on your stand-in use case, I think you should "invert" your schema. Each document will represent a lecture and will be tagged with its theme, edition, and event:
{
"_id" : ObjectId("54da1ff0a9ce603a239c3075"),
"event" : "X0004",
"edition" : "A0002,
"theme" : "RT0005",
"votes" : 22
}
event, edition, and theme can be some kind of identifiers, and might be references to event, edition, and theme documents in other collections. To cast a vote for a particular lecture, just update it by _id:
db.test.update({ "_id" : ObjectId("54da1ff0a9ce603a239c3075") }, { "$inc" : { "votes" : 1 } })
While I don't know your full requirements, I think this is a better basic design given your example use case.