Composite Primary Key - @IdClass - Mapper
When a database table contains a primary key made of 2 or more columns, we use a class to represent the primary key. In this example, we are using @IdClass annotation in the Entity class. The Entity class has all attributes from the table and each attribute that is a compound primary key, we annotate it with @Id. Still, we create a separated class with only the columns that are primary key. This class could be named EntityPK and it will replace the ID in the JpaRepository implementation.
With this approach (@IdClass), we can use query methods (as we're using here). We can also use Oracle sequences for all attribute/column. Using embedded annotation won't let us work with oracle Sequences for fields in the composite primary key.
We're using mapper from org.mapstruct. This helps us mappinng entity to DTO and vice versa. In the pom: org.mapstruct mapstruct 1.4.1.Final
The following plugin is useful to generate the mapper implementation during the build:
org.apache.maven.plugins
maven-compiler-plugin
3.5.1
Oracle database script: create table TB_ERROR_GAME ( GAME_ID NUMBER(4), GAME_PLATFORM NVARCHAR2(7), ERROR_SEQUENCE_NUMBER NUMBER(11),
ERROR_CODE NUMBER(3), ERROR_MESSAGE NVARCHAR2(255),
constraint ERROR_GAME_PK primary key (GAME_ID, GAME_PLATFORM, ERROR_SEQUENCE_NUMBER));