bug in MapSchema encode?

[amir-arad]

re-encoding a MapSchema with primitive values fails. added a failing test but could not grasp the changeTree mechanism enough to fix it.

[amir-arad]

This workaround works for me (FYI): cloning the inflated object before encoding,
const secondEncoded = decodedState1.clone().encodeAll();

[amir-arad]

@endel give me a clue here? how to fix?

[endel]

Hi @amir-arad, thanks for the reproduction case, this sounds the same as #115.

The use-case of re-encoding a decoded structure was not planned initially. Inside the $changes structure there is an allChanges property that contains the indexes of fields that should be encoded during .encodeAll().

When decoding a MapSchema (and every other "collection"), the allChanges property is not getting populated

schema/src/changes/ChangeTree.ts

Line 122 in 905c540

allChanges = new Set<number>();

I think ideally we should have a "encoding" and "decoding" mode to avoid having unnecessary extra overhead in the client-side (such as the allChanges = new Set() above). Current architecture is a bit messy and can't easily support this.

If we can support this without adding too much extra overhead it would be nice though!

[amir-arad]

@endel I can't pretend to understand the mechanism yet, but I hope this is an appropriate fix.
taking on bigger changes ("encoding" and "decoding" modes) is a bit too much for me ATM.

BTW: my first and most naïve fix attempt broke the filters test, and when debugging that I got a glimpse of that feature. Very impressive! Simplifying the architecture is a challenge, no doubt.

[endel]

Thanks for this @amir-arad 🎉