CODEWITHSUNDEEP
javapostgresqljsonbspring-data-jdbc
Anil Bharadia
Anil Bharadia

Reputation: 2820

Persist Java Map as PostgreSQL jsonb using spring data jdbc

I am using spring-data-jdbc to persist the following entity into PostgreSQL

@Table("abc_configurations")
data class AbcConfiguration(
    val name: String,
    val distribution: Map<String, Int>
)

The distribution is a jsonb column in PostgreSQL table:

CREATE TABLE abc_configurations
(
    name          VARCHAR(50)    PRIMARY KEY,
    distribution  JSONB    NOT NULL
);

I have created the following custom converter for this:

import com.fasterxml.jackson.core.type.TypeReference
import com.fasterxml.jackson.databind.ObjectMapper
import org.postgresql.util.PGobject
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.core.convert.converter.Converter
import org.springframework.data.convert.ReadingConverter
import org.springframework.data.convert.WritingConverter
import org.springframework.data.jdbc.core.convert.JdbcCustomConversions
import org.springframework.data.jdbc.core.convert.JdbcValue
import org.springframework.data.jdbc.repository.config.AbstractJdbcConfiguration
import org.springframework.data.jdbc.repository.config.EnableJdbcRepositories
import java.sql.JDBCType

@Configuration
@EnableJdbcRepositories
class DataConfig : AbstractJdbcConfiguration() {

    @Autowired
    private lateinit var objectMapper: ObjectMapper;

    @Bean
    override fun jdbcCustomConversions(): JdbcCustomConversions {
        val converters = listOf(
            DistributionWritingConverter(objectMapper),
            DistributionReadingConverter(objectMapper)
        )
        return JdbcCustomConversions(converters)
    }

    @WritingConverter
    class DistributionWritingConverter(private val objectMapper: ObjectMapper) : Converter<Map<String, Int>, JdbcValue> {
        override fun convert(source: Map<String, Int>): JdbcValue {
            return JdbcValue.of(objectMapper.writeValueAsString(source), JDBCType.VARCHAR)
        }
    }

    @ReadingConverter
    class DistributionReadingConverter(private val objectMapper: ObjectMapper) : Converter<PGobject, Map<String, Int>> {
        override fun convert(source: PGobject): Map<String, Int> {
            return objectMapper.readValue(source.value, object : TypeReference<Map<String, Int>>() {})
        }
    }
}

When I persist an Entity, it works fine, and the distribution Map gets persisted into JSONB column as expected.

The issue is when I read the entity, I am getting following Error: Couldn't find PersistentEntity for type class java.lang.Integer!

org.springframework.data.mapping.MappingException: Couldn't find PersistentEntity for type class java.lang.Integer!
    at org.springframework.data.mapping.context.MappingContext.getRequiredPersistentEntity(MappingContext.java:79) ~[spring-data-commons-2.4.5.jar:2.4.5]
    at org.springframework.data.jdbc.core.convert.SqlGeneratorSource.lambda$getSqlGenerator$0(SqlGeneratorSource.java:62) ~[spring-data-jdbc-2.1.5.jar:2.1.5]
    at java.base/java.util.concurrent.ConcurrentMap.computeIfAbsent(ConcurrentMap.java:330) ~[na:na]
    at org.springframework.data.jdbc.core.convert.SqlGeneratorSource.getSqlGenerator(SqlGeneratorSource.java:61) ~[spring-data-jdbc-2.1.5.jar:2.1.5]
    at org.springframework.data.jdbc.core.convert.DefaultDataAccessStrategy.sql(DefaultDataAccessStrategy.java:583) ~[spring-data-jdbc-2.1.5.jar:2.1.5]
    at org.springframework.data.jdbc.core.convert.DefaultDataAccessStrategy.findAllByPath(DefaultDataAccessStrategy.java:362) ~[spring-data-jdbc-2.1.5.jar:2.1.5]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[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:564) ~[na:na]
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.3.4.jar:5.3.4]

I have tried changing the @ReadingConverter method to following which did not work:

The ReadingConverter is not being used.

How can I tell spring to use the custom @ReadingConverter

Update (01.09.2021):

As mentioned by Jen and Susan, this is an issue with the spring-data-jdbc library. I moved ahead with the following work around.

data class Distribution(val value: Map<String, Int>)


@Table("abc_configurations")
data class AbcConfiguration(
    val name: String,
    val distribution: Distribution
)

Upvotes: 2

Views: 3635

Answers (1)

Jens Schauder
Jens Schauder

Reputation: 81907

Maps do get special handling in Spring Data JDBC so you can't simple use converters for them. Instead wrap the map in a custom type and register converters for that type.

Upvotes: 2

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