Integer literal cannot be converted to non Integer.class numeric types

[lukaseder]

Bug Report

Versions

• Driver: 0.8.4.RELEASE
• SPI: 0.9.0.M1
• Database: 1.4.200
• Java: openjdk version "11.0.9.1" 2020-11-04
• OS: Microsoft Windows [Version 10.0.19042.867]

Current Behavior

Querying SELECT 1 requires fetching the value as Integer.class, when any other numeric type should work, too.

Steps to reproduce

Run this:

System.out.println((
    Flux.from(connectionFactory.create())
        .flatMap(c -> c
            .createStatement("select 1")
            .execute())
        .flatMap(it -> it.map((r, m) -> r.get(0, Byte.class)))
        .collectList()
        .block()
));

To produce:

Exception in thread "main" java.lang.IllegalArgumentException: Cannot decode value of type java.lang.Byte
	at io.r2dbc.h2.codecs.DefaultCodecs.decode(DefaultCodecs.java:60)
	at io.r2dbc.h2.H2Row.get(H2Row.java:66)
	at org.jooq.testscripts.R2DBC.lambda$2(R2DBC.java:40)
	at io.r2dbc.h2.H2Result.lambda$map$0(H2Result.java:67)
	at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:106)
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:127)
	at reactor.core.publisher.FluxIterable$IterableSubscription.slowPath(FluxIterable.java:270)
	at reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:228)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:169)
	at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2193)
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onSubscribe(FluxOnErrorResume.java:74)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96)
	at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:164)
	at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8185)
	at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:426)
	at reactor.core.publisher.FluxFlatMap$FlatMapMain.tryEmit(FluxFlatMap.java:543)
	at reactor.core.publisher.FluxFlatMap$FlatMapInner.onNext(FluxFlatMap.java:984)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:127)
	at reactor.core.publisher.FluxIterable$IterableSubscription.slowPath(FluxIterable.java:270)
	at reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:228)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:169)
	at reactor.core.publisher.FluxFlatMap$FlatMapInner.onSubscribe(FluxFlatMap.java:964)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96)
	at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:164)
	at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8185)
	at reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:200)
	at reactor.core.publisher.FluxFlatMap.subscribeOrReturn(FluxFlatMap.java:93)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8171)
	at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:426)
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:127)
	at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1815)
	at reactor.core.publisher.MonoSupplier.subscribe(MonoSupplier.java:61)
	at reactor.core.publisher.Mono.subscribe(Mono.java:4099)
	at reactor.core.publisher.Mono.block(Mono.java:1702)
	at org.jooq.testscripts.R2DBC.main(R2DBC.java:42)
	Suppressed: java.lang.Exception: #block terminated with an error
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99)
		at reactor.core.publisher.Mono.block(Mono.java:1703)
		... 1 more

Expected behavior/code

This should work like it does in JDBC or other r2dbc drivers

Possible Solution

Convert the type in Java, or cast it in SQL as a workaround:

System.out.println((
    Flux.from(connectionFactory.create())
        .flatMap(c -> c
            .createStatement("select 1")
            .execute())
        .flatMap(it -> it.map((r, m) -> r.get(0, Byte.class)))
        .collectList()
        .block()
));