Datastore query throws exception when querying an entity that has a double property of 1.0

[avoivo]

Hello, i am using gcloud's datastore library and stumble into a strange problem. When i query on an entity that has a double value property without precision (ie 1.00, 2.00) , the following exception is thrown.

Unhandled exception:
type 'int' is not a subtype of type 'double' of 'value' where
  int is from dart:core
  double is from dart:core

#0      Value.doubleValue= (package:googleapis/datastore/v1.dart:1870:15)
#1      Value.Value.fromJson (package:googleapis/datastore/v1.dart:1927:7)
#2      Entity.Entity.fromJson.<anonymous closure> (package:googleapis/datastore/v1.dart:614:70)
#3      mapMap.<anonymous closure> (package:_discoveryapis_commons/src/clients.dart:916:28)
#4      _HashVMBase&MapMixin&&_LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:348)
#5      mapMap (package:_discoveryapis_commons/src/clients.dart:911:10)
#6      Entity.Entity.fromJson (package:googleapis/datastore/v1.dart:614:20)
#7      EntityResult.EntityResult.fromJson (package:googleapis/datastore/v1.dart:666:20)
#8      QueryResultBatch.QueryResultBatch.fromJson.<anonymous closure> (package:googleapis/datastore/v1.dart:1619:65)
#9      MappedListIterable.elementAt (dart:_internal/iterable.dart:412)
#10     ListIterable.toList (dart:_internal/iterable.dart:219)
#11     QueryResultBatch.QueryResultBatch.fromJson (package:googleapis/datastore/v1.dart:1619:95)
#12     RunQueryResponse.RunQueryResponse.fromJson (package:googleapis/datastore/v1.dart:1822:19)
#13     ProjectsResourceApi.runQuery.<anonymous closure> (package:googleapis/datastore/v1.dart:307:41)
#14     _rootRunUnary (dart:async/zone.dart:1158)
#15     _CustomZone.runUnary (dart:async/zone.dart:1037)
#16     _FutureListener.handleValue (dart:async/future_impl.dart:131)
#17     _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:637)
#18     _Future._propagateToListeners (dart:async/future_impl.dart:667)
#19     _Future._complete (dart:async/future_impl.dart:467)
#20     Stream.join.<anonymous closure> (dart:async/stream.dart:685)
#21     _rootRun (dart:async/zone.dart:1146)
#22     _CustomZone.run (dart:async/zone.dart:1026)
#23     _CustomZone.runGuarded (dart:async/zone.dart:924)
#24     _BufferingStreamSubscription._sendDone.sendDone (dart:async/stream_impl.dart:384)
#25     _BufferingStreamSubscription._sendDone (dart:async/stream_impl.dart:394)
#26     _BufferingStreamSubscription._close (dart:async/stream_impl.dart:278)
#27     _SinkTransformerStreamSubscription._close (dart:async/stream_transformers.dart:95)
#28     _EventSinkWrapper.close (dart:async/stream_transformers.dart:18)
#29     _StringAdapterSink.close (dart:convert/string_conversion.dart:267)
#30     _Utf8ConversionSink.close (dart:convert/string_conversion.dart:324)
#31     _ConverterStreamEventSink.close (dart:convert/chunked_conversion.dart:96)
#32     _SinkTransformerStreamSubscription._handleDone (dart:async/stream_transformers.dart:140)
#33     _rootRun (dart:async/zone.dart:1146)
#34     _CustomZone.run (dart:async/zone.dart:1026)
#35     _CustomZone.runGuarded (dart:async/zone.dart:924)
#36     _BufferingStreamSubscription._sendDone.sendDone (dart:async/stream_impl.dart:384)
#37     _BufferingStreamSubscription._sendDone (dart:async/stream_impl.dart:394)
#38     _BufferingStreamSubscription._close (dart:async/stream_impl.dart:278)
#39     _ForwardingStream._handleDone (dart:async/stream_pipe.dart:116)
#40     _ForwardingStreamSubscription._handleDone (dart:async/stream_pipe.dart:184)
#41     _rootRun (dart:async/zone.dart:1146)
#42     _CustomZone.run (dart:async/zone.dart:1026)
#43     _CustomZone.runGuarded (dart:async/zone.dart:924)
#44     _BufferingStreamSubscription._sendDone.sendDone (dart:async/stream_impl.dart:384)
#45     _BufferingStreamSubscription._sendDone (dart:async/stream_impl.dart:394)
#46     _BufferingStreamSubscription._close (dart:async/stream_impl.dart:278)
#47     _SinkTransformerStreamSubscription._close (dart:async/stream_transformers.dart:95)
#48     _EventSinkWrapper.close (dart:async/stream_transformers.dart:18)
#49     _ByteAdapterSink.close (dart:convert/byte_conversion.dart:68)
#50     _FilterSink.close (dart:io/data_transformer.dart:524)
#51     _ConverterStreamEventSink.close (dart:convert/chunked_conversion.dart:96)
#52     _SinkTransformerStreamSubscription._handleDone (dart:async/stream_transformers.dart:140)
#53     _rootRun (dart:async/zone.dart:1146)
#54     _CustomZone.run (dart:async/zone.dart:1026)
#55     _CustomZone.runGuarded (dart:async/zone.dart:924)
#56     _BufferingStreamSubscription._sendDone.sendDone (dart:async/stream_impl.dart:384)
#57     _BufferingStreamSubscription._sendDone (dart:async/stream_impl.dart:394)
#58     _BufferingStreamSubscription._close (dart:async/stream_impl.dart:278)
#59     _ForwardingStream._handleDone (dart:async/stream_pipe.dart:116)
#60     _ForwardingStreamSubscription._handleDone (dart:async/stream_pipe.dart:184)
#61     _rootRun (dart:async/zone.dart:1146)
#62     _CustomZone.run (dart:async/zone.dart:1026)
#63     _CustomZone.runGuarded (dart:async/zone.dart:924)
#64     _BufferingStreamSubscription._sendDone.sendDone (dart:async/stream_impl.dart:384)
#65     _BufferingStreamSubscription._sendDone (dart:async/stream_impl.dart:394)
#66     _DelayedDone.perform (dart:async/stream_impl.dart:609)
#67     _StreamImplEvents.handleNext (dart:async/stream_impl.dart:706)
#68     _PendingEvents.schedule.<anonymous closure> (dart:async/stream_impl.dart:666)
#69     _rootRun (dart:async/zone.dart:1150)
#70     _CustomZone.run (dart:async/zone.dart:1026)
#71     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:953)
#72     _microtaskLoop (dart:async/schedule_microtask.dart:41)
#73     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#74     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:394)
#75     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:414)
#76     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:148)

I have created an example of the behavior HERE

[mkustermann]

Thanks for the bug report @avoivo !

You appear to be using package:gcloud/src/datastore_impl.dart (which internally is based upon package:googleapis/datastore/v1.dart which uses a JSON based api). So it appears that the query result returned by the server does not encode the double value as a doubles in the JSON response but rather as integers if it's a whole number (javascript does not know the difference either).

If at all, it is a bug in the discoveryapis_generator, but the schema actually specifies it is a double value (see schema). Maybe we should move the issue over there - it could probably be fixed by calling toDouble() on values returned from the server which are specified to be of type double.

Longer term we will not be using the json-based API anymore.

The package:appengine is using internally a gRPC-based implementation of datastore. Are you using the package:appengine?

[avoivo]

Hello @mkustermann and thank you for your detailed reply.

After some research, me and a colleague of mine found out about the gRPC-based implementation of datastore that exists inside the appengine and decided to give it a try. It worked.

Long story short, we have implemented a rest api written in dart that runs on googles container engine and my question is , is it safe to use the gRPC-based implementation of datastore in production?

[avoivo]

Closing this in favor of google/googleapis.dart#18