Ember Data Snapshot and how to detect changes?

Question

I'm writing my own adapter/serializer. In order to send data to backend, I have to detect changes in DS.Snapshot and original Ember object. For ordinary attributes, it is possible to changedAttributes() but I did not found a way how to detect changes in hasMany relations.

I can detect new relation using snapshot.hasMany('foo') and changedAttributes(). But this approach is not able to find deleted relations.

see https://stackoverflow.com/questions/43947061/how-to-detect-and-save-relation-change-in-ember-2-13-0 — Christopher Milne, Nov 23 '17 at 15:18
I don't like the proposed solution but it has pointed me to a right direction. — Marek Grác, Nov 24 '17 at 12:24

score 0 · Accepted Answer · answered Nov 24 '17 at 14:57

Ember (2.x) does not track relations (e.g. hasMany) but it is possible to use ember-addon ember-data-change-tracker that can almost do it. It allows you to (auto-)save the current state of relations and afterwards you can compare this 'saved' (=old state) with the current state. You have to find a difference by yourself. A simple example from adapter:

snapshot.hasMany('users').length <-- current count of relations
snapshot.record.savedTrackerValue('users').length <-- old count of relations

Thanks to Christoper for pointing me to the right direction.

Ember Data Snapshot and how to detect changes?

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