Inheritance

Jimmer supports entity inheritance without giving up its immutable object model, typed query DSL, fetchers, DTO language, or save commands.

Two relational mapping strategies are available:

• SINGLE_TABLE stores the whole hierarchy in one table.
• JOINED stores common properties in the root table and properties declared by derived entity types in additional tables.

Both strategies use a discriminator column in the root table. A root query materializes the actual entity subtype automatically, and mutations keep the discriminator and all physical tables consistent.

This section covers:

• Declaring the hierarchy and choosing a mapping strategy
• Polymorphic queries, fetchers, and type operations
• Save commands, update/delete statements, and type changes
• Polymorphic DTOs and inputs

info

This feature is entity inheritance. @MappedSuperclass remains useful for sharing properties without creating a polymorphic entity hierarchy.