@Embedded

@Embedded maps a nested object property onto a group of columns on the same table — as opposed to @Link, which relates to rows in a different table. See Embedded Objects for the full guide.

function Embedded(
  type?: TypeThunk,
  options?: EmbeddedFieldOptions,
): PropertyDecorator;

class PersonName {
  @Column({ fieldName: 'given_name' })
  declare given?: string;

  @Column({ fieldName: 'family_name' })
  declare family?: string;
}

@Entity('customers')
class Customer {
  @Embedded(PersonName)
  declare name: PersonName;
}

type can be the embedded class itself, or a thunk (() => Type | Promise<Type>) to avoid circular imports; if omitted, it's inferred from the property's declared TS type via reflection (throws "type" must be defined if that isn't a class). The embedded type does not need its own @Entity decorator — only @Column-decorated properties.

fieldNamePrefix / fieldNameSuffix

@Embedded(Address, { fieldNamePrefix: 'address_' })
declare address: Address;

Because an embedded object's columns live on the same table as everything else, fieldNamePrefix (prepended) and/or fieldNameSuffix (appended) are typically needed to avoid column-name collisions — each is applied to every embedded column's own fieldName. See Embedded Objects for a full worked example.

EmbeddedFieldOptions reference

type EmbeddedFieldOptions = Partial<
  Omit<EmbeddedFieldMetadata, 'entity' | 'name' | 'kind' | 'type'>
>;

Option	Type	Description
fieldNamePrefix	string	Prepended to every embedded column's fieldName.
fieldNameSuffix	string	Appended to every embedded column's fieldName.
hidden	boolean	Never returned, even if explicitly requested in projection.
exclusive	boolean	Only returned when explicitly requested in projection.

Embedding an @Entity class as JSON instead

Nesting another @Entity-decorated class as the declared type of a plain @Column (not @Embedded) is a different feature — see @Column → Type inference.