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[firebase database] Iterate over snapshot.value - snapshot.forEach doesn't exist #11799

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[firebase database] Iterate over snapshot.value - snapshot.forEach doesn't exist#11799
Labels
p: firebaseObsolete - Firebase plugins

Description

@gurmukhp
gurmukhp
opened on Aug 28, 2017

Steps to Reproduce

I'm new to using Flutter / Dart, apologise in advance if this is something very basic. I've checked through all the documentation for the firebase database plugin and checked all the codelabs, this (what I deem simple) action is frustratingly hard to achieve.

final DatabaseReference reference = FirebaseDatabase.instance.reference().child('/');
final DataSnapshot snapshot = await reference.once();
print(snapshot.value); // returns a JSON object in the console.

How do I iterate over this value? I have tried to cast snapshot.value to a Map<String, String> and also tried snapshot.value.forEach (as in the docs) but this isn't supported.

The flutter logs are unfortunately also not very useful:

Logs

Reloaded 1 of 446 libraries in 464ms.
[VERBOSE-2:dart_error.cc(16)] Unhandled exception:
	NoSuchMethodError: Class '_InternalLinkedHashMap' has no instance method 'call'.
	Receiver: _LinkedHashMap len:1
	Tried calling: call()
	#0      Object._noSuchMethod (dart:core-patch/object_patch.dart:42)
	#1      Object.noSuchMethod (dart:core-patch/object_patch.dart:46)
	#2      _MyHomePageState.printFirebaseData (/Users/gurmukh/Library/Developer/CoreSimulator/Devices/96A5FE84-FD46-4A01-884B-E38069E0671E/data/Containers/Data/Application/8A200DD5-9395-4CFB-9545-E6B1C96D7F82/tmp/cryptoporfolioxS4M60/cryptoporfolio/lib/main.dart:73:14)
	<asynchronous suspension>
	#3      _MyHomePageState.build (/Users/gurmukh/Library/Developer/CoreSimulator/Devices/96A5FE84-FD46-4A01-884B-E38069E0671E/data/Containers/Data/Application/8A200DD5-9395-4CFB-9545-E6B1C96D7F82/tmp/cryptoporfolioxS4M60/cryptoporfolio/lib/main.dart:79:5)
	#4      StatefulElement.build (package:flutter/src/widgets/framework.dart:3624:27)
	#5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3534:15)
	#6      Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#7      StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#8      Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#9      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#10     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#11     ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#12     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#13     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#14     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#15     StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
	#16     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#17     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#18     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#19     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4250:32)
	#20     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4631:17)
	#21     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#22     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#23     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#24     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#25     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#26     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#27     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#28     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#29     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#30     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#31     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#32     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#33     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#34     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#35     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#36     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#37     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#38     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#39     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#40     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#41     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#42     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#43     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#44     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#45     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#46     StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
	#47     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#48     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#49     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#50     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#51     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#52     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#53     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#54     ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#55     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#56     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#57     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#58     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#59     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#60     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#61     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#62     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#63     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#64     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#65     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#66     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#67     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#68     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#69     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#70     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4250:32)
	#71     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4631:17)
	#72     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#73     _TheatreElement.update (package:flutter/src/widgets/overlay.dart:507:16)
	#74     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#75     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#76     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#77     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#78     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#79     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#80     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#81     ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#82     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#83     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#84     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#85     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#86     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#87     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#88     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#89     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#90     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#91     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#92     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#93     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#94     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#95     StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#96     Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#97     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#98     Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#99     StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
	#100    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#101    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#102    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#103    ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#104    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#105    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#106    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#107    ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#108    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#109    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#110    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#111    ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#112    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#113    SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
	#114    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#115    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#116    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#117    StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
	#118    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#119    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#120    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#121    StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
	#122    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#123    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#124    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#125    StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#126    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#127    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#128    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#129    ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#130    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#131    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#132    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#133    ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#134    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#135    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#136    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#137    StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
	#138    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#139    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#140    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#141    StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#142    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#143    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#144    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#145    ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
	#146    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#147    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#148    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#149    StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
	#150    Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
	#151    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
	#152    Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
	#153    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2260:33)
	#154    BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:503:20)
	#155    BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:189:5)
	#156    BindingBase&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:695:15)
	#157    BindingBase&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:643:9)
	#158    BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/rendering/binding.dart:275:20)
	#159    Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:21)
	#160    _Timer._runTimers (dart:isolate-patch/timer_impl.dart:366)
	#161    _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:394)
	#162    _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:151)

Activity

  1. gurmukhp
    changed the title [-]snapshot.forEach doesn't exist.[/-] [+]snapshot.forEach doesn't exist. [firebase-database][/+] on Aug 28, 2017
  2. gurmukhp
    changed the title [-]snapshot.forEach doesn't exist. [firebase-database][/-] [+][firebase database] Iterate over snapshot.value - snapshot.forEach doesn't exist[/+] on Aug 28, 2017
  3. gurmukhp
    closed this as completedon Aug 28, 2017
  4. eseidelGoogle
    added
    p: firebaseObsolete - Firebase plugins
    on Aug 28, 2017

  5. kroikie commented on Oct 13, 2019

    @kroikie
    kroikie
    on Oct 13, 2019

    @gurmukhp

    This issue has been moved to firebase/flutterfire#971. Any further collaboration will be done there.

  6. kroikie
    added
    transferred
    on Oct 13, 2019

  7. github-actions commented on Aug 27, 2021

    @github-actions
    github-actionsbot
    on Aug 27, 2021

    This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

  8. github-actions
    locked as resolved and limited conversation to collaborators on Aug 27, 2021
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