NgRepeat compiled to JS throws NullError #1097

ufoscout · 2014-06-03T19:45:14Z

We are preparing a Sortable component for the next version of the Angular UI library (https://pub.dartlang.org/packages/angular_ui).
It works fine in Dartium, but when compiled to JS, the NgRepeat directive often throws a NullError.
Here the error stack in Chrome:

TypeError: Cannot read property 'set$_childHead' of null
    at Scope.destroy$0 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:11797:26)
    at NgRepeat__onChange_closure2.call$1 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:15937:23)
    at _CollectionChangeRecord.forEachRemoval$1 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:53360:11)
    at NgRepeat._onChange$1 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:15802:17)
    at NgRepeat_expression_closure0.call$2 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:15886:19)
    at Watch.reactionFn$2 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:24887:30)
    at Watch.invoke$0 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:24897:12)
    at RootWatchGroup.detectChanges$5$changeLog$evalStopwatch$exceptionHandler$fieldStopwatch$processStopwatch (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:24835:26)
    at RootScope.digest$0 (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:12110:34)
    at RootScope.<anonymous> (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:11750:12)
    at RootScope.Scope.apply$2 [as apply$0] (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:11756:19)
    at eval [as call$0] (eval at <anonymous> (http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:3172:14), <anonymous>:2:37)

And here the staketrace in FF (similar but not the same):

NullError: this._parentScope is null

STACKTRACE:
.Scope.destroy$0<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:11797
.NgRepeat__onChange_closure2.call$1<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:15937
._CollectionChangeRecord.forEachRemoval$1@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:53360
.NgRepeat._onChange$1<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:15802
.NgRepeat_expression_closure0.call$2<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:15886
.Watch.reactionFn$2@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:24887
.Watch.invoke$0@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:24897
.RootWatchGroup.detectChanges$5$changeLog$evalStopwatch$exceptionHandler$fieldStopwatch$processStopwatch@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:24835
.RootScope.digest$0<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:12110
.Scope.apply$2<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:11750
.Scope.apply$2<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:11756
anonymous/<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:3172
._rootRun<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:28762
._ZoneDelegate.run$2@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:31478
.VmTurnZone._finishTurn$2<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:12917
.VmTurnZone._onRunBase$4<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:12883
.VmTurnZone._onRunUnary$5<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:12890
anonymous/<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:3184
._ZoneDelegate.runUnary$3@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:31485
._CustomizedZone.runUnary$2@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:31668
._BaseZone.runUnaryGuarded$2@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:31568
._BaseZone_bindUnaryCallback_closure.call$1<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:31626
.invokeClosure_closure0.call$0@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:4358
._IsolateContext.eval$1<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:1833
._callInIsolate@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:1466
.invokeClosure<@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:3017
.convertDartClosureToJS/$function@http://127.0.0.1:3030/angular.dart.ui/build/web/main.dart.js:3036

To reproduce the issue, checkout the dragdrop branch (https://github.com/akserg/angular.dart.ui/tree/dragdrop) and compile it to JS (pub build). Open the build result in a browser, drag of an element of a sortable list performing fast movements with the mouse. The exception is thrown multiple times and the content of the list is corrupted.
As stated before, everything works perfectly with Dart code in Dartium.

The text was updated successfully, but these errors were encountered:

vicb · 2014-06-03T19:59:20Z

@ufoscout could you please try to apply the commits from #1018 and let us know if the situation improves after having merged the first and both the commits ?

ufoscout · 2014-06-03T20:27:42Z

@vicb I don't know exactly how to apply the commits you mentioned; however, I performed a checkout of angular.dart master, I copied the raw version of the NgRepeat from #1018 (I added a print to the constructor to be sure it was used) and then I modified my library to use angular from local path.
As before, it works with Dart/Dartium but it throws an error with JS/Firefox/Chrome.

vicb · 2014-06-03T20:35:12Z

git apply could have helped here but what you've done is perfectly fine.

Some other things you can do to investigate:

try to use angular from the master branch (by using a path pkg) - you'll probably need to adapt some code, check the examples and ask if something is not clear,
try to come with the minimal example that triggers the error, there is a lot of code in the linked repo.

Thanks

ufoscout · 2014-06-03T21:36:02Z

@vicb I performed different attempts but no luck at all.
I have been able to create a small project that reproduces the issue, it can be checked out here:
https://github.com/ufoscout/NgRepeatIssue
It does not start at all in Firefox (another strange thing...); however, the error can be easily reproduced with Chrome. In this new project the error appears less often than in the original one. It seems that it is related to the speed the actions are performed. To reproduce it you have to move the mouse very (very very) fast during a drag operation.

vicb · 2014-06-04T08:31:54Z

Firefox does not work (as reported)
I can not trigger the issue with Chrome, what VM version do you use, could you try with Dart VM version: 1.5.0-dev.3.4

My setup:

Ubuntu 14.04 64b
Dart VM version: 1.5.0-dev.3.4 (Mon Jun 2 08:43:55 2014) on "linux_x64"
Chrome Version 37.0.2017.2 dev
Firefox 30.0

vicb · 2014-06-04T08:36:36Z

Seems like I can trigger the error finally, I'll take a deeper look

vicb · 2014-06-04T10:08:22Z

For now it seems like a bug in the change detection, see what happens when dragging an item to the bottom of the list:

drag node [7] over node [6] js_primitives.dart:25
++  _onCollectionChange js_primitives.dart:25
moveFn 7 -> 6 js_primitives.dart:25
moveFn 6 -> 7 js_primitives.dart:25
moveFn 8 -> 8 js_primitives.dart:25
moveFn 9 -> 9 js_primitives.dart:25
drag node [8] over node [7] js_primitives.dart:25
++  _onCollectionChange js_primitives.dart:25
moveFn 8 -> 7 js_primitives.dart:25
moveFn 7 -> 8 js_primitives.dart:25
moveFn 9 -> 9 js_primitives.dart:25
drag node [9] over node [8] js_primitives.dart:25
++  _onCollectionChange js_primitives.dart:25
remove at index 9 js_primitives.dart:25
destroying scope :0:0:9 js_primitives.dart:25
moveFn 9 -> 8 js_primitives.dart:25
moveFn 8 -> 9

We should not remove / destroy at index 9 - we should only swap the two last els (8 & 9)

I have now to check if this is also applicable to the Dart version... and fix it :)

vicb · 2014-06-04T10:11:48Z

The Dart version is fine

++  _onCollectionChange
moveFn 7 -> 6
moveFn 6 -> 7
moveFn 8 -> 8
moveFn 9 -> 9
drag node [8] over node [7]
++  _onCollectionChange
moveFn 8 -> 7
moveFn 7 -> 8
moveFn 9 -> 9
drag node [9] over node [8]
++  _onCollectionChange
moveFn 9 -> 8
moveFn 8 -> 9

vicb · 2014-06-04T11:45:30Z

This snippet shows the bad behavior (also in Dart)

  var detector = new DirtyCheckingChangeDetector(null);

  var iterator;

  var list = ['a', 'b', 'c'];
  detector.watch(list, null, null);
  iterator = detector.collectChanges()..moveNext();
  print(iterator.current.currentValue);

  list..clear()..addAll(['b', 'a', 'c']);
  iterator = detector.collectChanges()..moveNext();
  print(iterator.current.currentValue);

  list..clear()..addAll(['b', 'c', 'a']);
  iterator = detector.collectChanges()..moveNext();
  print(iterator.current.currentValue);

I don't know why but this seems to work in a unit test !
Anyway I'm closer to resolution than ever berfore ;)

vicb · 2014-06-04T11:50:02Z

Ah got it: it works in checked mode, fails in non checked mode - nothing to do with JS vs Dart

ufoscout · 2014-06-04T12:56:59Z

@vicb wow! You're going fast 👍 Thank you. I'm looking forward to see this fixed!

vicb · 2014-06-04T13:01:26Z

I have a fix but I need to make sure everything is correct before merging, this code is critical

akserg · 2014-06-04T14:45:22Z

Thanks Victor,
Very appreciated you effort. Hope to see bug fix in next release.

Sergey.

closes dart-archive#1097

vicb · 2014-06-04T17:06:15Z

Well I'm quite happy to have fixed this bug that I was chasing for some time - thanks @ufoscout for having provided a repro.
I have also found an other issue while working on this, the move N -> N should not happen, this one will be for next week

ufoscout · 2014-06-04T19:35:58Z

@vicb you fixed it in less than 24 hours! impressive! I really need to thank you.

closes #1097 Conflicts: lib/change_detection/dirty_checking_change_detector.dart

closes dart-archive#1097

vicb mentioned this issue Jun 4, 2014

We should also run the test in non-checked mode #1103

Open

ufoscout mentioned this issue Jun 4, 2014

Create Sortable akserg/angular.dart.ui#64

Closed

vicb added a commit to vicb/angular.dart that referenced this issue Jun 4, 2014

fix(dccd): fix removals reporting

d2784ea

closes dart-archive#1097

vicb added a commit to vicb/angular.dart that referenced this issue Jun 4, 2014

fix(dccd): fix removals reporting

f2a3692

closes dart-archive#1097

vicb added a commit to vicb/angular.dart that referenced this issue Jun 4, 2014

fix(dccd): fix removals reporting

0a40cee

closes dart-archive#1097

vicb added a commit to vicb/angular.dart that referenced this issue Jun 4, 2014

fix(dccd): fix removals reporting

0131117

closes dart-archive#1097

vicb closed this as completed in 8dbeefc Jun 4, 2014

This was referenced Jun 13, 2014

RangeError in ng-repeat #1121

Closed

ng-repeat fails after reordering collection #1154

Closed

naomiblack added the Performance label Jun 25, 2014

vicb added a commit that referenced this issue Jul 9, 2014

fix(dccd): fix removals reporting

86df529

closes #1097 Conflicts: lib/change_detection/dirty_checking_change_detector.dart

dsalsbury pushed a commit to dsalsbury/angular.dart that referenced this issue Jul 16, 2014

fix(dccd): fix removals reporting

00664c3

closes dart-archive#1097

dsalsbury pushed a commit to dsalsbury/angular.dart that referenced this issue Jul 16, 2014

fix(dccd): fix removals reporting

51d8495

closes dart-archive#1097

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NgRepeat compiled to JS throws NullError #1097

NgRepeat compiled to JS throws NullError #1097

ufoscout commented Jun 3, 2014

vicb commented Jun 3, 2014

ufoscout commented Jun 3, 2014

vicb commented Jun 3, 2014

ufoscout commented Jun 3, 2014

vicb commented Jun 4, 2014

vicb commented Jun 4, 2014

vicb commented Jun 4, 2014

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vicb commented Jun 4, 2014

vicb commented Jun 4, 2014

ufoscout commented Jun 4, 2014

vicb commented Jun 4, 2014

akserg commented Jun 4, 2014

vicb commented Jun 4, 2014

ufoscout commented Jun 4, 2014

NgRepeat compiled to JS throws NullError #1097

NgRepeat compiled to JS throws NullError #1097

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ufoscout commented Jun 3, 2014

vicb commented Jun 3, 2014

ufoscout commented Jun 3, 2014

vicb commented Jun 3, 2014

ufoscout commented Jun 3, 2014

vicb commented Jun 4, 2014

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akserg commented Jun 4, 2014

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ufoscout commented Jun 4, 2014