Adding custom dependency in Random-JPA

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There are many systems which doesn’t have proper foreign key relationship. In order to create relationship with other entities, random-jpa provides dependencies to be added to JPAContextFactory. Based on these provided custom dependencies and foreign key relationship, a JPAContext is created.

Let us continue with our application, suppose application want to maintain an audit trail of all the inventories ordered by an employee. But there is no foreign key relationship between the tables.

Problem statement

I want to create new EmployeeInventoryAudit entries for a customer. So during my complete application lifcycle, EmployeeInventoryAudit depends on Employee, but there is no foreign key relationship in table so random-JPA will not be able to derive this relationship automatically.

We will have to provide custom dependency at the application level(random-JPA also provides test level dependency as softLinks);

Table setup

Add Table:

CREATE TABLE employee_inventory_audit (
    id           INT             NOT NULL AUTO_INCREMENT,
    emp_no      INT             NOT NULL,
    inventory   VARCHAR(40)     NOT NULL,
    quantity   INT     NOT NULL,
    PRIMARY KEY (id)
);

Entity:

@Entity
@Table(name = "employee_inventory_audit")
public class EmployeeInventoryAudit {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Basic
    @Column(name = "emp_no")
    private Integer employeeNumber;

    @Basic
    @Column(name = "inventory")
    private String inventory;

    @Basic
    @Column(name = "quantity")
    private Integer quantity;

    @Basic
    @Column(name = "purchase_date")
    private LocalDate purchaseDate;

    // Getter & Setter        
}

And static meta model:

@StaticMetamodel(EmployeeInventoryAudit.class)
public class EmployeeInventoryAudit_ {

    public static volatile SingularAttribute<EmployeeInventoryAudit, Integer> id;
    public static volatile SingularAttribute<EmployeeInventoryAudit, Integer> employeeNumber;
    public static volatile SingularAttribute<EmployeeInventoryAudit, String> inventory;
    public static volatile SingularAttribute<EmployeeInventoryAudit, Integer> quantity;
    public static volatile SingularAttribute<EmployeeInventoryAudit, LocalDate> purchaseDate;

}

Adding custom dependency in Random-JPA

So as per the business logic, employeeNumber attribute of EmployeeInventoryAudit depends on employee’s customerNumber.

And we will tell the same thing to Random-JPA context factory while creating jpaContext.

    final Dependencies dependencies = Dependencies.newInstance();
    dependencies.withLink(Link.newLink(EmployeeInventoryAudit_.employeeNumber, Employee_.empNo));
    
    final JPAContext jpaContext = JPAContextFactory
                    .newInstance(Database.MY_SQL, entityManager)
                    .with(dependencies)
                    .generate();

Now if you generate EmployeeInventoryAudit using JPAContext:

    @Test @Transactional
    public void createEmployeeInventoryAudit() {

        final ResultMap resultMap = jpaContext.createAndPersist(Entity.of(EmployeeInventoryAudit.class));

        resultMap.print(System.out::println);

    }

It would create employee followed by employee_inventory_audit.

└── *ROOT*
    └── in.kuros.randomjpa.blogexample.entity.Employee|0 [empNo: 10023]
        └── in.kuros.randomjpa.blogexample.entity.EmployeeInventoryAudit|0 [id: 1]

It behaves same as if employee_inventory_audit(emp_no) has foreign key to employees(emp_no) table.

Complete configuration

@Configuration
public class TestConfig {

    @Autowired private EntityManager entityManager;

    @Bean
    public JPAContext createJpaContext() {
        return JPAContextFactory
                .newInstance(Database.MY_SQL, entityManager)
                .with(getDependencies())
                .generate();
    }

    private Dependencies getDependencies() {
        final Dependencies dependencies = Dependencies.newInstance();
        dependencies.withLink(Link.newLink(EmployeeInventoryAudit_.employeeNumber, Employee_.empNo));

        return dependencies;
    }
}

checkout the Commit History on github

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Updated:

Kumar Rohit
WRITTEN BY

Kumar Rohit

I like long drives, bike trip & good food. I have passion for coding, especially for Clean-Code.

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