Android Room's does not accept generic field type [73534868]

Fixed

Bug

Status Update

No update yet.

Description

rm...@gmail.com

created issue #1

Feb 17, 2018 08:01PM

Component used: Room
Version used: 1.0.0 and 1.1.0 alpha2
Devices/Android versions reproduced on: Android Studio 3.1 Beta 3

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I'm trying to have a base class which id field is of a generic type like

class BaseEntity<T>{
private T id;
//get, set;
}
class User extends BaseEntity<String> {
//blah blah blah
}
and I have a DAO like this:

@Dao
public interface UserDao {

@Query("SELECT * FROM user WHERE id = :id")
Flowable<User> getUserById(String id);
}
and I get a compilation error:

app\build\generated\source\apt\irrisimples\debug\com\irrisimples\data\source\local\UserDao_Impl.java:275: error: cannot find symbol final T _tmpId; ^

and in UserDao_Impl:275:

final T _tmpId; _tmpId = _cursor.getString(_cursorIndexOfId);

So this means that Room couldn't figure out what was T and replace the value there. Is it a bug or am I doing something wrong?

related question on S.O.:

https://stackoverflow.com/questions/48845327/android-rooms-does-not-accept-generic-field-type

Comments

yb...@google.com <yb...@google.com> #2Feb 17, 2018 09:02PM

Assigned to yb...@google.com.

that is a bug. we should be able to resolve it properly.

yb...@google.com <yb...@google.com> #3Feb 20, 2018 04:46AM

interesting, this works fine if the generic field is public final but does not work w/ getters setters.

yb...@google.com <yb...@google.com> #4Feb 20, 2018 06:10AM

ok, turns out we are not properly processing methods when processing pojos.
That is why it works when I use a field.

I've created a CL that fixes the problem. Until it is shipped, you can workaround the problem by making that field public (preferably public final if possible).

Thanks for the report.

yb...@google.com <yb...@google.com> #5Feb 20, 2018 04:17PM

Marked as fixed.

should be fixed in 1.1.0-alpha3

rm...@gmail.com <rm...@gmail.com> #6Feb 20, 2018 04:56PM

Thanks!!!

jo...@gmail.com <jo...@gmail.com> #7Mar 23, 2018 10:06AM

I may have made another mistake, but using @Embedded on the generic type doesn't seem to work for me. Sounds like it could be related to the fix. Do I open another bug for that one?

jo...@gmail.com <jo...@gmail.com> #8Mar 23, 2018 10:15AM

Oops, submitted before attaching the example. Here it is:

public class BaseEntity<T extends BaseEmbeddedType> {
@Embedded
public T embeddedType;
}

Am I wrong in expecting this to work? It fails with an IllegalArgumentException in the Room processor:

Caused by: java.lang.IllegalArgumentException
at com.google.auto.common.MoreElements$2.defaultAction(MoreElements.java:95)
at com.google.auto.common.MoreElements$2.defaultAction(MoreElements.java:93)
at com.sun.tools.javac.code.Symbol$TypeVariableSymbol.accept(Symbol.java:821)
at com.google.auto.common.MoreElements.asType(MoreElements.java:125)
at com.google.auto.common.MoreTypes.asTypeElement(MoreTypes.java:541)
at android.arch.persistence.room.processor.PojoProcessor.processEmbeddedField(PojoProcessor.kt:367)
at android.arch.persistence.room.processor.PojoProcessor.doProcess(PojoProcessor.kt:150)
at android.arch.persistence.room.processor.PojoProcessor.access$doProcess(PojoProcessor.kt:73)
at android.arch.persistence.room.processor.PojoProcessor$process$1.invoke(PojoProcessor.kt:104)
at android.arch.persistence.room.processor.PojoProcessor$process$1.invoke(PojoProcessor.kt:73)
at android.arch.persistence.room.processor.cache.Cache$Bucket.get(Cache.kt:46)
at android.arch.persistence.room.processor.PojoProcessor.process(PojoProcessor.kt:101)
at android.arch.persistence.room.processor.EntityProcessor.doProcess(EntityProcessor.kt:68)
at android.arch.persistence.room.processor.EntityProcessor.access$doProcess(EntityProcessor.kt:50)
at android.arch.persistence.room.processor.EntityProcessor$process$1.invoke(EntityProcessor.kt:57)
at android.arch.persistence.room.processor.EntityProcessor$process$1.invoke(EntityProcessor.kt:50)
at android.arch.persistence.room.processor.cache.Cache$Bucket.get(Cache.kt:46)
at android.arch.persistence.room.processor.EntityProcessor.process(EntityProcessor.kt:56)
at android.arch.persistence.room.processor.DatabaseProcessor.processEntities(DatabaseProcessor.kt:248)
at android.arch.persistence.room.processor.DatabaseProcessor.doProcess(DatabaseProcessor.kt:63)
at android.arch.persistence.room.processor.DatabaseProcessor.process(DatabaseProcessor.kt:53)
at android.arch.persistence.room.RoomProcessor$DatabaseProcessingStep.process(RoomProcessor.kt:57)
at com.google.auto.common.BasicAnnotationProcessor.process(BasicAnnotationProcessor.java:318)
at com.google.auto.common.BasicAnnotationProcessor.process(BasicAnnotationProcessor.java:171)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
at com.sun.tools.javac.main.Main.compile(Main.java:523)
... 52 more