Ronny Bräunlich ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=62f2786... ) *created* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiNmVmZTkxZmJi... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-16662?atlOrigin=eyJpIjoiNmVmZT... ) HHH-16662 ( https://hibernate.atlassian.net/browse/HHH-16662?atlOrigin=eyJpIjoiNmVmZT... ) Postgres Mapping of JSON column to Map<> causes class cast exception ( https://hibernate.atlassian.net/browse/HHH-16662?atlOrigin=eyJpIjoiNmVmZT... ) Issue Type: Bug Affects Versions: 6.2.2 Assignee: Unassigned Components: hibernate-core Created: 22/May/2023 01:05 AM Environment: PostgreSQL 14.3 PostgreSQL driver version 42.6.0 Hibernate Core 6.2.2.Final JDK 19 Priority: Major Reporter: Ronny Bräunlich ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=62f2786... ) Hi everyone, I execute a native query via Spring Data JPA and dynamically insert them into a projection interface. The database column definition is a jsonb column and the interface I select into has a field: val properties: Map<String, Any?> the original entity has the backing field defined like this: import io.hypersistence.utils.hibernate.type.json.JsonType ... @Type(JsonType::class) @Column(columnDefinition = "jsonb") val properties: Map<String, Any?> With Hibernate 6.1.7.Final it would work because in the method buildJdbcTypeCodeToJavaClassMappings in JdbcTypeJavaClassMappings (see https://github.com/hibernate/hibernate-orm/blob/6.1.7/hibernate-core/src/... ) there was no mapping defined for the JSON type. Therefore, Object.class has been returned and in the end the Map was passed on as is. With Hibernate 6.2.x and https://hibernate.atlassian.net/browse/HHH-15748 the implementation changed and now JSON is mapped to String.class all times. This causes a ClassCastException during my persistence tests: class java.lang.String cannot be cast to class java.util.Map I wonder why with the Oracle specific task the mapping has been changed in a central class, since Oracle became its own OracleTypes class. ( https://hibernate.atlassian.net/browse/HHH-16662#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16662#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100225- sha1:bbd69a1 )