https://github.com/cepr0/hibernate-types-in-projection

Bad attempt to use json or array types of hibernate-types lib in Spring Data projections
https://github.com/cepr0/hibernate-types-in-projection

array hibernate-types json postgresql projection spring-data-jpa

Last synced: 3 months ago
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Bad attempt to use json or array types of hibernate-types lib in Spring Data projections

• Host: GitHub
• URL: https://github.com/cepr0/hibernate-types-in-projection
• Owner: Cepr0
• Created: 2018-12-10T20:45:03.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2018-12-10T21:03:09.000Z (over 7 years ago)
• Last Synced: 2025-09-26T15:34:56.660Z (9 months ago)
• Topics: array, hibernate-types, json, postgresql, projection, spring-data-jpa
• Language: Java
• Homepage:
• Size: 4.88 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

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README

          
An attempt to use json/array types of [hibernate-types](https://github.com/vladmihalcea/hibernate-types) in Spring Data projections

Projection:

```java

public interface ParentProjection {

	String getName();

	List getChildNames();

}

```

Query:

```java

@Query(value = "" +

        "select " +

        "  p.name as name, " +

        "  array_agg(c.name) as childNames " +

        "from " +

        "  parents p " +

        "  join children c on c.parent_id = p.id " +

        "where " +

        "  p.id = ?1 " +

        "group by " +

        "  p.name" +

        "", nativeQuery = true)

Optional getParentWithChildNamesAsArray(Integer id);

```

[Custom Postgres dialect](https://vladmihalcea.com/hibernate-no-dialect-mapping-for-jdbc-type/):

```java

public class PostgreSQLCustomDialect extends PostgreSQL95Dialect {

	public PostgreSQLCustomDialect() {

		super();

		registerHibernateType(Types.OTHER, JsonNodeStringType.class.getName());

		registerHibernateType(Types.ARRAY, StringArrayType.class.getName());

	}

}

```

When PostgreSQL aggregate function `array_agg` is used in the query above, 

then the following exception is raised:

    org.springframework.orm.jpa.JpaSystemException: Could not instantiate Type: com.vladmihalcea.hibernate.type.array.StringArrayType;

    

If `json_agg` function is used, then we have another exception:

    java.lang.IllegalArgumentException: Projection type must be an interface!