Support for shard keys in embedded documents

[mgoffin]

Currently _object_key() only supports shard keys that are Document-level attributes, but MongoDB supports shard keys that are in embedded documents.

There does not seem to be a way using meta's shard_key to define these embedded shard keys in such a way that allows updates and saves to work again.

This seems to be an issue in 0.7, 0.8, dev, and master branches. I am currently having this issue with the 0.8.3 release.

[rozza]

The following works for me:

def test_shard_key(self):

    class Machine(EmbeddedDocument):
        name = StringField()
        version = IntField()

    class LogEntry(Document):
        machine = EmbeddedDocumentField(Machine)
        log = StringField()

        meta = {
            'shard_key': ('machine',)
        }

    LogEntry.drop_collection()

    machine = Machine(name="T1", version=1)

    log = LogEntry(machine=machine).save()

    log.log = "Saving"
    log.save()

Is it that you want to use part of an embedded document?

[mgoffin]

Yes. Using your example, machine.name would be the shard key of interest as opposed to machine itself.

[rozza]

ok - I'll mark for 9.0