@TypeConverter object expressions [151110764]

Fixed

Bug

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Description

yo...@google.com

created issue #1

Mar 9, 2020 11:04PM

At the moment, types annotated with `@TypeConverter` must be instantiable. This prevents object expressions from being used as type converters. Since type converters are fairly likely to be pure functions adapting serialization/deserialization functions, it'd be useful if object expressions were supported.

The output generated by the Room processor for this input won't compile, because the generated Java tries to "new" the object expression type:

```kt
@Database(entities = [FooEntity::class], version = 1, exportSchema = false)
internal abstract class FooDatabase : RoomDatabase() {
abstract fun fooDao(): FooDao
}

@Entity(tableName = "foo")
@TypeConverters(FooTypeConverters::class)
data class FooEntity internal constructor(
@PrimaryKey val id: Int,

val proto: SomeProto
)

object FooTypeConverters {
@TypeConverter
fun toSomeProto(bytes: ByteArray): SomeProto {
return SomeProto.parseFrom(bytes)
}

@TypeConverter
fun toBytes(someProto: SomeProto): ByteArray {
return someProto.toByteArray()
}
}
```

Comments

yb...@google.com <yb...@google.com> #2Mar 9, 2020 11:38PM

yea we should probably special case these to find the instance. meanwhile, quick workaround is to mark those methods JVMStatic.

ap...@google.com <ap...@google.com> #3Jun 5, 2020 04:15PM

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

commit 8dd4a965ebf301007a75fa26ab77dd7c53f0e043
Author: Yigit Boyar <yboyar@google.com>
Date: Tue Jun 02 16:11:22 2020

Support TypeConverters on kotlin objects

This CL adds support for having @TypeConverter annotated methods
on kotlin objects.

I also noticed that KotlinMetadata tests were not running as they dont
trigger the compilation. Fixed them as well.

Bug: 151110764
Test: KotlinTestApp, KotlinMetadataElementTest
Change-Id: I93eb2ff7162706ff7538159a748ecbe62bb1d9fe

M room/compiler/src/main/kotlin/androidx/room/kotlin/KotlinClassMetadataUtils.kt
M room/compiler/src/main/kotlin/androidx/room/kotlin/KotlinMetadataElement.kt
M room/compiler/src/main/kotlin/androidx/room/processor/CustomConverterProcessor.kt
M room/compiler/src/main/kotlin/androidx/room/solver/types/CustomTypeConverterWrapper.kt
M room/compiler/src/main/kotlin/androidx/room/vo/CustomTypeConverter.kt
M room/compiler/src/test/kotlin/androidx/room/kotlin/KotlinMetadataElementTest.kt
M room/integration-tests/kotlintestapp/src/androidTest/java/androidx/room/integration/kotlintestapp/vo/DateConverter.kt

https://android-review.googlesource.com/1323097

yb...@google.com <yb...@google.com> Jun 5, 2020 09:29PM

Marked as fixed.

Issue 151110764

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Comments

yb...@google.com <yb...@google.com> #2Mar 9, 2020 11:38PM

ap...@google.com <ap...@google.com> #3Jun 5, 2020 04:15PM

yb...@google.com <yb...@google.com> Jun 5, 2020 09:29PM

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