Nullable MutableLiveData gives an error when set to null [169249668]

Fixed

Bug

Status Update

No update yet.

Description

sp...@gmail.com

created issue #1

Sep 24, 2020 01:40PM

Component used:

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version"

Version used: 2.2.0 and 2.3.0-alpha07

Devices/Android versions reproduced on: N/A

ViewModels with more than one MutableLiveData get their nullability wrong.

Example:

class ExampleViewModel : ViewModel() {

    val data1 = MutableLiveData<Int>()

    val data2 = MutableLiveData<Int?>()

    fun funct() {
        data1.value = 1
        data2.value = null
    }
}

This gives the error Error: Cannot set non-nullable LiveData value to null [NullSafeMutableLiveData]

Comments

sp...@gmail.com <sp...@gmail.com> #2Sep 24, 2020 01:41PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit b90079595f33f58fece04026a97faa0d243acdb1
Author: Yuichi Araki <yaraki@google.com>
Date: Wed Sep 18 16:55:49 2019

Change the way to detect mismatch between POJO and query

This fixes cursor mismatch warnings with expandProjection.

Bug: 140759491
Test: QueryMethodProcessorTest
Change-Id: I7659002e5e0d1ef60fc1af2a625c0c36da0664d8

M room/compiler/src/main/kotlin/androidx/room/processor/QueryMethodProcessor.kt
M room/compiler/src/main/kotlin/androidx/room/solver/TypeAdapterStore.kt
M room/compiler/src/main/kotlin/androidx/room/solver/query/result/PojoRowAdapter.kt
M room/compiler/src/test/kotlin/androidx/room/processor/QueryMethodProcessorTest.kt
M room/compiler/src/test/kotlin/androidx/room/testing/TestProcessor.kt

https://android-review.googlesource.com/1123258

https://goto.google.com/android-sha1/b90079595f33f58fece04026a97faa0d243acdb1

se...@google.com <se...@google.com> Sep 24, 2020 02:43PM

Reassigned to jb...@google.com.

la...@gmail.com <la...@gmail.com> #3Jan 5, 2021 05:33AM

The following changes were cherrypicked through Coastguard (

https://android-build.googleplex.com/coastguard/)
Release Track: (

https://android-build.googleplex.com/coastguard/dashboard/6093116828680192/#/cherrypickHistory/all)
Created: 2019-10-14 17:23:42.610596+00:00
Changes: aosp/1123258

ma...@gmail.com <ma...@gmail.com> #4Mar 4, 2021 02:38PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit bdde5a1a970ddc9007b28de4aa29d60ffa588f08
Author: Yigit Boyar <yboyar@google.com>
Date: Thu Apr 16 16:47:05 2020

Re-factor how errors are dismissed when query is re-written

This CL changes how we handle errors/warnings if query is
re-written.
There was a bug in expandProjection where we would report warnings
for things that Room already fixes automatically (

b/140759491

).
The solution to that problem (I7659002e5e0d1ef60fc1af2a625c0c36da0664d8)
solved it by deferring validating of columns until after re-write
decision is made. Unfortunately, this required changing PojoRowAdapter
to have a dummy mapping until it is validating, make it hard to use
as it does have a non-null mapping which is not useful.

This CL partially reverts that change and instead rely on the log
deferring logic we have in Context. This way, we don't need to break
the stability of PojoRowAdapter while still having the ability to
drop warnings that room fixes. This will also play nicer when we
have different query re-writing options that can use more information
about the query results.

Bug: 153387066
Bug: 140759491
Test: existing tests pass
Change-Id: I2ec967c763d33d7a3ff02c1a13c6953b460d1e5f

M room/compiler/src/main/kotlin/androidx/room/log/RLog.kt
M room/compiler/src/main/kotlin/androidx/room/processor/QueryMethodProcessor.kt
M room/compiler/src/main/kotlin/androidx/room/solver/TypeAdapterStore.kt
M room/compiler/src/main/kotlin/androidx/room/solver/query/result/PojoRowAdapter.kt

https://android-review.googlesource.com/1288456

sp...@gmail.com <sp...@gmail.com> #5Mar 4, 2021 02:57PM

It already existed in 2.2.0.

[Deleted User] <[Deleted User]> #6Mar 9, 2021 02:45PM

For me, this started to happen when I updated the libs to 2.3.0. If I downgrade them to 2.2.0, the error disappears.

ap...@google.com <ap...@google.com> #7Mar 11, 2021 07:06PM

Project: platform/frameworks/support
Branch: androidx-main

commit d5adf6168357145df07976060f0ae88dfdb05fe8
Author: Jeremy Woods <jbwoods@google.com>
Date: Mon Mar 08 14:17:49 2021

Fix MutableLiveData lint rule false report

If using multiple MutableLiveData variables as fields and mixed the
nullability, the lint rule could falsely report that a livedata value
was improperly being made null. This is because as constructed, it
didn't match up the fields with the assignments.

This change maps the field variable names to the reference types to
ensure that when reporting, the rule knows how to match them.

This also cleans up the rule by changing it to using a UastScanner.

Relnote: "The `NonNullableMutableLiveData` lint rule can now properly
differentiate between field variables with different nullability."
Test: added nullLiterallFailMultipleFieldsDifferent
Bug: 169249668

Change-Id: Ieb0270de1b22f3a10641643438bc2b9f1f5d72e8

M lifecycle/lifecycle-livedata-core-ktx-lint/src/main/java/androidx/lifecycle/lint/NonNullableMutableLiveDataDetector.kt
M lifecycle/lifecycle-livedata-core-ktx-lint/src/test/java/androidx/lifecycle/lint/NonNullableMutableLiveDataDetectorTest.kt

https://android-review.googlesource.com/1532131

jb...@google.com <jb...@google.com> #8Mar 11, 2021 10:23PM

This has been addressed internally and will be in the next lifecycle release.

You can follow the snapshot instructions using build id 7201697 with the lifecycle-livedata-core-ktx:2.4.0-SNAPSHOT dependency to verify.

sp...@gmail.com <sp...@gmail.com> #9Mar 11, 2021 11:23PM

Awesome! Thank you for fixing this.

jb...@google.com <jb...@google.com> Mar 11, 2021 11:46PM

Marked as fixed.

go...@gmail.com <go...@gmail.com> #10Apr 21, 2021 10:11PM

#FLHY

n....@tinkoff.ru <n....@tinkoff.ru> #11May 7, 2021 08:49AM

on 2.4.0-alpha01 androidx.lifecycle.lint.NonNullableMutableLiveDataDetector still doesn't work

Stack: ArrayIndexOutOfBoundsException:NonNullableMutableLiveDataDetector$createUastHandler$1.getFieldTypeReference(NonNullableMutableLiveDataDetector.kt:101)←NonNullableMutableLiveDataDetector$createUastHandler$1.visitClass(NonNullableMutableLiveDataDetector.kt:88)←UElementVisitor$DispatchPsiVisitor.visitClass(UElementVisitor.kt:602)←UElementVisitor$DelegatingPsiVisitor.visitClass(UElementVisitor.kt:1153)←AbstractKotlinUClass.accept(KotlinUClass.kt:63)←ImplementationUtilsKt.acceptList(implementationUtils.kt:23)←UFile$DefaultImpls.accept(UFile.kt:83)←KotlinUFile.accept(KotlinUFile.kt:30)

an...@gmail.com <an...@gmail.com> #12May 11, 2021 12:46PM

Please contact me

cu...@gmail.com <cu...@gmail.com> #13May 12, 2021 06:51AM

2.4.0-alpha01 still give error:

val currentUserId = MutableLiveData<String>()
fun setUserID(userId: String?) {
if (userId == null) {
return
}
val check: String = userId // no error
currentUserId.value = userId // error: Expected non-nullable value
}

cu...@gmail.com <cu...@gmail.com> #14May 12, 2021 07:19AM

It seems fixed in 2.4.0-SNAPSHOT

jo...@gmail.com <jo...@gmail.com> #15Jun 15, 2021 08:24PM

Is this fixed?

ya...@gmail.com <ya...@gmail.com> #16Jun 29, 2021 02:48PM

It still seems present in 2.4.0-alpha02:

Error: Cannot set non-nullable LiveData value to null [NullSafeMutableLiveData from jetified-lifecycle-livedata-core-ktx-2.4.0-alpha02

iv...@gmail.com <iv...@gmail.com> #17Jul 7, 2021 05:59PM

I've tested with the example above from: cu...@gmail.com<cu...@gmail.com> #13
There is a issue that is still happening on 2.4.0-alpha02 and in the snapshot version mentioned above.

js...@gmail.com <js...@gmail.com> #18Aug 12, 2021 05:18PM

What exactly is this thread context for and why am I the target on the command prompt etc

sp...@gmail.com <sp...@gmail.com> #19Aug 13, 2021 01:50PM

I think a new bug report should be created for comment #13. It's not the same issue as what I originally reported. The original issue is fixed and this issue should remain closed.

ad...@ade.se <ad...@ade.se> #20Sep 1, 2021 08:52AM

Here's a separate issue for the problem in comment #13

https://issuetracker.google.com/issues/198313895