java spring-webflux spring-data-r2dbc r2dbc-mysql

java.lang.Integer cannot be cast to class java.lang.Long in R2DBC mysql model classes

I use R2DBC MySQL driver in my Spring Webflux reactive web. And I try to execute table schema SQL script. But the script continuously cause errors.

First, I make 3 model classes.

User.java

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder 
@Table("blog_user") 
public class User {
     
    @Id
    @Column("user_id")
    private Long id;
    
    @Column
    private String username;
 
    @Column
    @JsonIgnore
    private String password;
     
    @Column
    private String fullname;
    
    @Column
    private Integer role;
}

Post.java

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
@Table
public class Post {
 
    @Id
    @Column("post_id")
    private Long id;
    
    @Column
    private String title;
  
    @Column
    private String body;
        
    @Column("created_date")
    private LocalDateTime createdDate;
    
    @Column("user_id")
    private User user;
    
    @Column("posts")
    private Collection<Tag> tags;
}

Tag.java

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
@Table
public class Tag {
  
    @Id
    @Column("tag_id")
    private Long id;
    
    @Column
    private String body;
    
    @Column("created_date")
    private LocalDateTime createdDate;
    
    @Column("post_id")
    private Post post;
        
    @Column("user_id")
    private User user;
}

schema.sql

-- TABLE intialized.
DROP TABLE IF EXISTS tag;
DROP TABLE IF EXISTS post;
DROP TABLE IF EXISTS blog_user;


-- TABLE created.
CREATE TABLE IF NOT EXISTS blog_user (
    user_id BIGINT NOT NULL,
    username VARCHAR(30) NOT NULL,
    password VARCHAR(255) NOT NULL,
    email VARCHAR(255),
    fullname VARCHAR(255),
    role SMALLINT CHECK (role IN (0, 1)),

    PRIMARY KEY (user_id),
    UNIQUE (username)
);

CREATE TABLE IF NOT EXISTS post (
    post_id BIGINT NOT NULL,
    title VARCHAR(30) NOT NULL,
    body TEXT,
    created_date DATETIME(6) NOT NULL,
    user_id BIGINT NOT NULL,

    PRIMARY KEY (post_id),
    FOREIGN KEY (user_id) REFERENCES blog_user (user_id)
);

CREATE TABLE IF NOT EXISTS tag(
    tag_id BIGINT NOT NULL,
    body VARCHAR(255),
    created_date DATETIME(6) NOT NULL,
    post_id BIGINT NOT NULL,
    user_id BIGINT NOT NULL,

    PRIMARY KEY (tag_id),
    FOREIGN KEY (post_id) REFERENCES post (post_id),
    FOREIGN KEY (user_id) REFERENCES blog_user (user_id)
);

Below configuration method executes schema.sql.

reactive web initializer method

@Bean
ConnectionFactoryInitializer initializer(ConnectionFactory connectionFactory) {

        ConnectionFactoryInitializer initializer = new ConnectionFactoryInitializer();
        initializer.setConnectionFactory(connectionFactory);
        
        ResourceDatabasePopulator databasePopulator = new ResourceDatabasePopulator();
        databasePopulator.addScripts(new ClassPathResource(schema.sql));
        initializer.setDatabasePopulator(databasePopulator);


        return initializer;
}

However, initially executed schema.sql throws errors,

Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled.
[2m2023-01-01T09:06:30.943+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.945+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.947+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.948+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.951+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.953+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.955+09:00[0;39m [33m WARN[0;39m [35m10464[0;39m [2m---[0;39m [2m[actor-tcp-nio-3][0;39m [36mdev.miku.r2dbc.mysql.MySqlConnection    [0;39m [2m:[0;39m The server timezone is <???ѹα? ǥ?ؽ> that's unknown, trying to use system default timezone
[2m2023-01-01T09:06:30.974+09:00[0;39m [31mERROR[0;39m [35m10464[0;39m [2m---[0;39m [2m[  restartedMain][0;39m [36mo.s.boot.SpringApplication              [0;39m [2m:[0;39m Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'initializer' defined in class path resource [com/aaa/blog/wf/config/BlogWebFluxConfig.class]: Failed to execute SQL script statement #1 of class path resource [sql/spring-boot-mysql-schema.sql]: DROP TABLE IF EXISTS tag
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1751) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:599) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:521) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:961) ~[spring-beans-6.0.3.jar:6.0.3]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:915) ~[spring-context-6.0.3.jar:6.0.3]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:584) ~[spring-context-6.0.3.jar:6.0.3]
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-3.0.1.jar:3.0.1]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) ~[spring-boot-3.0.1.jar:3.0.1]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:432) ~[spring-boot-3.0.1.jar:3.0.1]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) ~[spring-boot-3.0.1.jar:3.0.1]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1302) ~[spring-boot-3.0.1.jar:3.0.1]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1291) ~[spring-boot-3.0.1.jar:3.0.1]
    at com.aaa.blog.wf.SpringBlogWebFluxMySqlApplication.main(SpringBlogWebFluxMySqlApplication.java:10) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-3.0.1.jar:3.0.1]
Caused by: org.springframework.r2dbc.connection.init.ScriptStatementFailedException: Failed to execute SQL script statement #1 of class path resource [sql/spring-boot-mysql-schema.sql]: DROP TABLE IF EXISTS tag
    at org.springframework.r2dbc.connection.init.ScriptUtils.lambda$runStatement$9(ScriptUtils.java:571) ~[spring-r2dbc-6.0.3.jar:6.0.3]
    at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:94) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.MonoStreamCollector$StreamCollectorSubscriber.onError(MonoStreamCollector.java:149) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.MonoStreamCollector$StreamCollectorSubscriber.onNext(MonoStreamCollector.java:126) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxFlatMap$FlatMapMain.tryEmit(FluxFlatMap.java:543) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxFlatMap$FlatMapInner.onNext(FluxFlatMap.java:984) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:122) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:200) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1839) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.NextProcessor.tryEmitValue(NextProcessor.java:358) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.NextProcessor.onNext(NextProcessor.java:298) ~[reactor-core-3.5.1.jar:3.5.1]
    at dev.miku.r2dbc.mysql.MySqlResult.lambda$null$3(MySqlResult.java:114) ~[r2dbc-mysql-0.8.2.RELEASE.jar:0.8.2.RELEASE]
    at reactor.core.publisher.LambdaSubscriber.onNext(LambdaSubscriber.java:160) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxWindowPredicate$WindowFlux.drainRegular(FluxWindowPredicate.java:670) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxWindowPredicate$WindowFlux.drain(FluxWindowPredicate.java:748) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxWindowPredicate$WindowFlux.onNext(FluxWindowPredicate.java:790) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.onNext(FluxWindowPredicate.java:241) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxHandleFuseable$HandleFuseableSubscriber.onNext(FluxHandleFuseable.java:193) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107) ~[reactor-core-3.5.1.jar:3.5.1]
    at dev.miku.r2dbc.mysql.util.DiscardOnCancelSubscriber.onNext(DiscardOnCancelSubscriber.java:70) ~[r2dbc-mysql-0.8.2.RELEASE.jar:0.8.2.RELEASE]
    at reactor.core.publisher.FluxPeekFuseable$PeekConditionalSubscriber.onNext(FluxPeekFuseable.java:854) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onNext(MonoFlatMapMany.java:250) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:200) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxHandle$HandleSubscriber.onNext(FluxHandle.java:128) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.FluxPeekFuseable$PeekConditionalSubscriber.onNext(FluxPeekFuseable.java:854) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:537) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.EmitterProcessor.tryEmitNext(EmitterProcessor.java:343) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.InternalManySink.emitNext(InternalManySink.java:27) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.core.publisher.EmitterProcessor.onNext(EmitterProcessor.java:309) ~[reactor-core-3.5.1.jar:3.5.1]
    at dev.miku.r2dbc.mysql.client.ReactorNettyClient$ResponseSink.next(ReactorNettyClient.java:340) ~[r2dbc-mysql-0.8.2.RELEASE.jar:0.8.2.RELEASE]
    at dev.miku.r2dbc.mysql.client.ReactorNettyClient.lambda$new$0(ReactorNettyClient.java:103) ~[r2dbc-mysql-0.8.2.RELEASE.jar:0.8.2.RELEASE]
    at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:185) ~[reactor-core-3.5.1.jar:3.5.1]
    at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:292) ~[reactor-netty-core-1.1.1.jar:1.1.1]
    at reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:401) ~[reactor-netty-core-1.1.1.jar:1.1.1]
    at reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:411) ~[reactor-netty-core-1.1.1.jar:1.1.1]
    at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:113) ~[reactor-netty-core-1.1.1.jar:1.1.1]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.handleDecoded(MessageDuplexCodec.java:187) ~[r2dbc-mysql-0.8.2.RELEASE.jar:0.8.2.RELEASE]
    at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.channelRead(MessageDuplexCodec.java:95) ~[r2dbc-mysql-0.8.2.RELEASE.jar:0.8.2.RELEASE]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346) ~[netty-codec-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318) ~[netty-codec-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1373) ~[netty-handler-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1236) ~[netty-handler-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1285) ~[netty-handler-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:529) ~[netty-codec-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:468) ~[netty-codec-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:290) ~[netty-codec-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.86.Final.jar:4.1.86.Final]
    at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
    Suppressed: java.lang.Exception: #block terminated with an error
        at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99) ~[reactor-core-3.5.1.jar:3.5.1]
        at reactor.core.publisher.Mono.block(Mono.java:1710) ~[reactor-core-3.5.1.jar:3.5.1]
        at org.springframework.r2dbc.connection.init.ConnectionFactoryInitializer.execute(ConnectionFactoryInitializer.java:112) ~[spring-r2dbc-6.0.3.jar:6.0.3]
        at org.springframework.r2dbc.connection.init.ConnectionFactoryInitializer.afterPropertiesSet(ConnectionFactoryInitializer.java:97) ~[spring-r2dbc-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1797) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1747) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:599) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:521) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:961) ~[spring-beans-6.0.3.jar:6.0.3]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:915) ~[spring-context-6.0.3.jar:6.0.3]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:584) ~[spring-context-6.0.3.jar:6.0.3]
        at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-3.0.1.jar:3.0.1]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) ~[spring-boot-3.0.1.jar:3.0.1]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:432) ~[spring-boot-3.0.1.jar:3.0.1]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) ~[spring-boot-3.0.1.jar:3.0.1]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1302) ~[spring-boot-3.0.1.jar:3.0.1]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1291) ~[spring-boot-3.0.1.jar:3.0.1]
        at com.aaa.blog.wf.SpringBlogWebFluxMySqlApplication.main(SpringBlogWebFluxMySqlApplication.java:10) ~[classes/:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
        at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
        at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-3.0.1.jar:3.0.1]
Caused by: java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.Long (java.lang.Integer and java.lang.Long are in module java.base of loader 'bootstrap')
    at java.base/java.util.stream.Collectors.lambda$summingLong$23(Collectors.java:699) ~[na:na]
    at reactor.core.publisher.MonoStreamCollector$StreamCollectorSubscriber.onNext(MonoStreamCollector.java:117) ~[reactor-core-3.5.1.jar:3.5.1]
    ... 67 common frames omitted

I think my reactive R2DBC model classes contains some errors. ClassCastException. But I have no idea what element has wrong class type. The printed error message show no code line number. I changed the id type of model class(User, Post, Tag) into Integer type, but the same errors are thrown.

Solution

If you are using https://github.com/mirromutth/r2dbc-mysql 0.8.x RELEASE and the latest Spring Boot 2.7 or Spring Boot 3.0.x, I think there is a compatibility issue between the R2dbc MySQL driver you are using and R2dbc SPI managed by Spring Boot.

In the latest Spring Boot 3.0, R2dbc SPI was updated to 1.0, which introduced several incompatible APIs since 0.8(r2dbc-mysql 0.8.x RELEASE is aligned with R2dbc SPI 0.8). I have encountered similar exceptions when upgrading to R2dbc 0.9 and 1.0 but used driver version is incompatible.

Try to use the latest MariaDB R2dbc Driver to connect your MySQL
Consider other database, eg. PostgreSQL or switch to MariaDB directly.

Update(2023-5-23): In the latest Spring Boot 3.x, it includes jasycn r2dbc mysql instead of the original r2dbc mysql driver which is not active and stick on the old R2dbc SPI 0.8.