I'm working on some changes for the officeradar
<https://github.com/tleyden/office-radar> demo app and trying to show a
list of profiles which I want to have reverse sorted by how recent they've
had a geofence event for that profile. Eg:
[Traun entered SF 5 hours ago]
[Zack entered SF 8 hours ago]
[Hideki entered MV 2 days ago]
The document model is as follows:
*Profile doc*
{
"_id":"tleyden",
"lastGeofenceEvent":"doc-234324232"
}
*GeofenceEvent doc*
{
"id":"doc-234324232",
"createdAt":"2014-10-24",
"beaconLocation":"sf"
}
As I was writing the map function to generate the UI mentioned above, I
wanted to emit the createdAt field, but realized that would require a doc
lookup. Eg:
Mapper map = new Mapper() {
@Override
public void map(Map<String, Object> document, Emitter
emitter) {
if (document.get("type").equals("profile")) {
// I have a profile doc, but I only have the id of
the
// latest geofence event associated with this
profile,
// and I'd need to do a db lookup to get it, which
// would violate the rules of a map function .. so
I'm stuck
}
}
};
*Proposed solution*
I figured I could add a new field to the profile doc to hold the date of
the latest geofence event associated with this profile (denormalize +
duplicate):
Profile doc (updated):
{
"_id":"tleyden",
"lastGeofenceEvent":"doc-234324232",
"lastGeofenceEventCreatedAt":"2014-10-24"
}
The map function would become:
if (document.get("type").equals("profile")) {
emit(document.get("lastGeofenceEventCreatedAt"),
...);
}
and the problem would be solved.
But, I'm wondering is this the best practice or is there a better way?
@Jens I remember in your advanced couchbase lite talk you mentioned "poor
man's joins", but I didn't catch the details. Would that apply here?
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