Mapping to JSON Fields with Spring Data R2DBC and Reactive MySQL Driver

Question

I'm trying to use JSON data type to store json data in a specific column in a MySQL database.

I followed this guide, and got storing and reading JSON working fine but now I get this error when trying to save another entity that have a boolean column/field:

Caused by: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.Byte] to type [boolean]
    at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:322)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:195)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:175)
    at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.getPotentiallyConvertedSimpleRead(MappingR2dbcConverter.java:277)
    at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.readValue(MappingR2dbcConverter.java:201)
    at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.readFrom(MappingR2dbcConverter.java:182)
    at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.read(MappingR2dbcConverter.java:136)
    at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.read(MappingR2dbcConverter.java:119)
    at org.springframework.data.r2dbc.convert.EntityRowMapper.apply(EntityRowMapper.java:46)
    at org.springframework.data.r2dbc.convert.EntityRowMapper.apply(EntityRowMapper.java:29)
    at dev.miku.r2dbc.mysql.MySqlResult.processRow(MySqlResult.java:176)
    at dev.miku.r2dbc.mysql.MySqlResult.handleResult(MySqlResult.java:149)
    at dev.miku.r2dbc.mysql.MySqlResult.lambda$map$1(MySqlResult.java:93)
    at reactor.core.publisher.FluxHandle$HandleSubscriber.onNext(FluxHandle.java:102)
    at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)
    at dev.miku.r2dbc.mysql.util.DiscardOnCancelSubscriber.onNext(DiscardOnCancelSubscriber.java:70)
    at reactor.core.publisher.FluxWindowPredicate$WindowFlux.drainRegular(FluxWindowPredicate.java:667)
    at reactor.core.publisher.FluxWindowPredicate$WindowFlux.drain(FluxWindowPredicate.java:745)
    at reactor.core.publisher.FluxWindowPredicate$WindowFlux.onNext(FluxWindowPredicate.java:787)
    at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.onNext(FluxWindowPredicate.java:265)
    at reactor.core.publisher.FluxHandleFuseable$HandleFuseableSubscriber.onNext(FluxHandleFuseable.java:184)
    at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)
    at dev.miku.r2dbc.mysql.util.DiscardOnCancelSubscriber.onNext(DiscardOnCancelSubscriber.java:70)
    at reactor.core.publisher.FluxPeekFuseable$PeekConditionalSubscriber.onNext(FluxPeekFuseable.java:854)
    at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onNext(MonoFlatMapMany.java:250)
    at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:199)
    at reactor.core.publisher.FluxHandle$HandleSubscriber.onNext(FluxHandle.java:118)
    at reactor.core.publisher.FluxPeekFuseable$PeekConditionalSubscriber.onNext(FluxPeekFuseable.java:854)
    at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:491)
    at reactor.core.publisher.EmitterProcessor.tryEmitNext(EmitterProcessor.java:299)
    at reactor.core.publisher.InternalManySink.emitNext(InternalManySink.java:27)
    at reactor.core.publisher.EmitterProcessor.onNext(EmitterProcessor.java:265)
    at dev.miku.r2dbc.mysql.client.ReactorNettyClient$ResponseSink.next(ReactorNettyClient.java:340)
    at dev.miku.r2dbc.mysql.client.ReactorNettyClient.lambda$new$0(ReactorNettyClient.java:103)
    at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:184)
    at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:280)
    at reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:389)
    at reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:405)
    at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
    at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.handleDecoded(MessageDuplexCodec.java:187)
    at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.channelRead(MessageDuplexCodec.java:95)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
    at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)
    at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:311)
    at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:432)
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
    at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1368)
    at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1234)
    at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1280)
    at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:507)
    at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:446)
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
    at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:719)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
    at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.base/java.lang.Thread.run(Thread.java:834)

If I don't create a R2dbcCustomConversions bean (as described in the guide) then I don't get this error but JSON doesn't work...

Is there another way to use JSON in my scenario?

Answer 1

Answering my own question - Looks like some sort of a bug in spring-data-r2dbc:

In R2dbcDataAutoConfiguration there is this bean definition:

@Bean
@ConditionalOnMissingBean
public R2dbcCustomConversions r2dbcCustomConversions() {
    List<Object> converters = new ArrayList<>(this.dialect.getConverters());
    converters.addAll(R2dbcCustomConversions.STORE_CONVERTERS);
    return new R2dbcCustomConversions(
            CustomConversions.StoreConversions.of(this.dialect.getSimpleTypeHolder(), converters),
            Collections.emptyList());
}

This is the bean we override when registering our converters (this is my code):

@Bean
public R2dbcCustomConversions r2dbcCustomConversions(JsonEventsReadingConverter readingConverter,
                                                     JsonEventsWritingConverter writingConverter) {
    val converters = new ArrayList<>();
    converters.add(readingConverter);
    converters.add(writingConverter);
    return new R2dbcCustomConversions(converters);
}

The CTOR new R2dbcCustomConversions(converters) takes care of adding some of the basic converters (STORE_CONVERSIONS & R2dbcConverters) but it does not add MySqlDialect.BooleanToByteConverter & MySqlDialect.ByteToBooleanConverter which takes care of the MySQL value to Java conversions.

I found an icky solution (Manually adding those converters in my bean) but I don’t see another way (Open to suggestions):

@Configuration
@RequiredArgsConstructor
public class R2dbcConvertorsConfig {
    private final DatabaseClient databaseClient;
    @Bean
    public R2dbcCustomConversions r2dbcCustomConversions(JsonEventsReadingConverter readingConverter,
                                                         JsonEventsWritingConverter writingConverter) {
        val dialect = DialectResolver.getDialect(this.databaseClient.getConnectionFactory());
        val converters = new ArrayList<>();
        converters.add(readingConverter);
        converters.add(writingConverter);
        converters.addAll(dialect.getConverters());
        return new R2dbcCustomConversions(converters);
    }
}

As requested:

package com.mycompany.platform.webhookdelivery.core.dal.converters;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.mycompany.platform.webhookdelivery.core.dal.entities.webhookfilters.JsonEvents;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.convert.converter.Converter;
import org.springframework.core.serializer.support.SerializationFailedException;
import org.springframework.data.convert.ReadingConverter;
import org.springframework.lang.NonNull;
import org.springframework.stereotype.Component;

import java.io.IOException;

@Slf4j
@ReadingConverter
@AllArgsConstructor
@Component
public class JsonEventsReadingConverter implements Converter<String, JsonEvents> {

    private final ObjectMapper objectMapper;

    @Override
    public JsonEvents convert(@NonNull String target) {
        try {
            String json = " {\"events\":" + target + "}";
            return objectMapper.readValue(json, JsonEvents.class);
        } catch (IOException e) {
            log.debug("Failed to deserialise  JSON: " + target, e);
            throw new SerializationFailedException("Failed to deserialize  JSON: " + target, e);
        }
    }
}

package com.mycompany.platform.webhookdelivery.core.dal.converters;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mycompany.platform.webhookdelivery.core.dal.entities.webhookfilters.JsonEvents;
import lombok.AllArgsConstructor;
import lombok.extern.log4j.Log4j2;
import org.springframework.core.convert.converter.Converter;
import org.springframework.core.serializer.support.SerializationFailedException;
import org.springframework.data.convert.WritingConverter;
import org.springframework.stereotype.Component;

@Log4j2
@WritingConverter
@AllArgsConstructor
@Component
public class JsonEventsWritingConverter implements Converter<JsonEvents, String> {

    private final ObjectMapper objectMapper;

    @Override
    public String convert(JsonEvents source) {

        try {
            return objectMapper.writeValueAsString(source.getEvents());
        } catch (JsonProcessingException e) {
            log.debug("Failed to serialise JSON: " + source, e);
            throw new SerializationFailedException("Failed to serialize JSON: " + source, e);
        }
    }
}