Realm-js: Sorting by sub objects

[digitalcatnip]

Assume I have the following schema:

var Car = {
   id: 'int',
   make: 'string',
   model: 'string',
};

var Person = {
   id: 'int',
   first_name: 'string',
   last_name: 'string',
};

var Passenger = {
   id: 'int',
   person: {type: 'Person'},
   car: {type: 'Car'},
};

If I do the following, I get the error Property 'person.last_name' does not exist on object type 'Passenger'.

realm.objects('Passenger').sorted('person.last_name')

Is my syntax incorrect, or is sorting by sub-objects not supported? If it's not supported, are there plans to support it?

[appden]

This is not currently support, but it's a great feature suggestion! For now, you can use Array.prototype.sort to do this manually. Something like this should work:

let passengers = realm.objects('Passenger').slice();
passengers.sort((a, b) => a.person.last_name.localeCompare(b.person.last_name));

[digitalcatnip]

@appden Thanks for the suggestion. My understanding is by keeping the objects wrapped in Results, any relevant database writes would get persisted to the result set. If I call slice(), I lose that ability, correct?

My thought was instead adding a last_name to the Passenger class, which would be sync'd manually by me with the underlying Person. I could then called sorted(last_name) on Passenger to achieve the same result while maintaining the Results object ability to auto-update.

[alazier]

Your solution sounds like it will work. We eventually will add support for custom sort functions but it will be a while before we have time to build it.

[edmofro]

Hey @alazier, when you say 'a while', do you have an ETA? Would be very valuable to be able to sort by a property of a child object.

[alazier]

@edmofro this wont happen until there is core support and I don't think that is on the near term roadmap. In the meantime you can use the workaround mentioned here https://github.com/realm/realm-js/issues/437#issuecomment-219551900

[bdash]

Support for this was added to core in realm/realm-core#1969 / realm/realm-core#2011.

[akashdmahali]

@bdash is this support available for the react native too ?? I started with realm for react native 3-4 days back but sorting based on nested keys doesnt seem to work

[bdash]

This issue tracks exposing core's support to React Native and Node.

[faogustavo]

Is it going to be added to RN too? I'm trying with latest version and does not work :/

[kristiandupont]

It will be added but isn't yet. This issue is for keeping track of it.

[ironage]

This has been implemented for a while (#1303) but for some reason this issue wasn't automatically closed.