Setting ParseObject `id` loses all pending operations

[grantland]

object = new Parse.Object('TestObject');
object.set('foo', 'bar');
object.set('id', '1234');
object.save(); // expected: { id: '1234' , 'foo': 'bar'}, actual: { id: '1234' }

or

object = new Parse.Object('TestObject');
object.set('foo', 'bar');
object.id = '1234';
object.save(); // expected: { id: '1234' , 'foo': 'bar'}, actual: { id: '1234' }

It looks like this is due to the fact that we map objectId to pending ops, so changing the objectId will map to a different or null pending ops.

My current workaround is to call object._migrateId('1234') instead.

[hallucinogen]

My immediate thought if we do _migrateId('1234') by default on set('id', newId) we'll break the following case due to static pending ops (https://github.com/ParsePlatform/Parse-SDK-JS/blob/master/src/ParseObject.js#L203):

objA = Parse.Query.get('1234'); // foo: bar
objB = Parse.Query.get('0'); // foo: baz
objA.id = 0;

objB.get('foo') // expected: baz, actual: bar

Killing the static pending ops/state might be the long term fix though I'm not sure that we want to do that.

[andrewimm]

We definitely don't want to kill the static state anytime soon, since that enables a lot more functionality than it complicates.

Definitely correct that we wouldn't want to call _migrateId() on set('id', ...), but we could copy the pending ops, eg:

objA = new Parse.Object({ className: 'Item', objectId: '1234' });
objB = new Parse.Object({ className: 'Item', objectId: '1234' });
// Objects are backed by the same data
objA.set({ foo: 'bar' });
assert(objB.get('foo') === 'bar');

objB.set({ id: '5678' });
assert(objA.get('foo') === 'bar');
assert(objB.get('foo') === 'bar');
objA.set({ foo: 'baz' });
assert(objA.get('foo') === 'baz');
assert(objB.get('foo') === 'bar');

[dplewis]

Closing for inactivity.