Multi column search using Specifications Spring Data Jpa within associated entity?

Question

I am taking this question Perform multi column search on Date, Integer and String Data type fields of Single Table? and This method must return a result of type Specification<Employee> in Java 8 further ahead.

Actually I wanted to search within association entity as well as a part of global search. Will that be possible using JPA 2 Specifications API ?

I've Employee and Department @OneToMany bi-directional relationship.

Employee.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class Employee implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "EMPLOYEE_ID")
    private Long employeeId;

    @Column(name = "FIRST_NAME")
    private String firstName;

    @Column(name = "LAST_NAME")
    private String lastName;

    @Column(name = "EMAIL_ID")
    private String email;

    @Column(name = "STATUS")
    private String status;

    @Column(name = "BIRTH_DATE")
    private LocalDate birthDate;

    @Column(name = "PROJECT_ASSOCIATION")
    private Integer projectAssociation;

    @Column(name = "GOAL_COUNT")
    private Integer goalCnt;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "DEPT_ID", nullable = false)
    @JsonIgnore
    private Department department;
}

Department.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class Department implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "DEPT_ID")
    private Long departmentId;

    @Column(name = "DEPT_NAME")
    private String departmentName;

    @Column(name = "DEPT_CODE")
    private String departmentCode;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "department")
    @JsonIgnore
    private Set<Employee> employees;
}

and I saved Data like below. MyPaginationApplication.java

@SpringBootApplication
public class MyPaginationApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(MyPaginationApplication.class, args);
    }

    @Autowired
    private EmployeeRepository employeeRepository;

    @Autowired
    private DepartmentRepository departmentRepository;

    @Override
    public void run(String... args) throws Exception {
        saveData();
    }

    private void saveData() {

        Department department1 = Department.builder()
                .departmentCode("AD")
                .departmentName("Boot Depart")
                .build();
        departmentRepository.save(department1);

        Employee employee = Employee.builder().firstName("John").lastName("Doe").email("john.doe@gmail.com")
                .birthDate(LocalDate.now())
                .goalCnt(1)
                .projectAssociation(2)
                .department(department1)
                .build();
        Employee employee2 = Employee.builder().firstName("Neha").lastName("Narkhede").email("neha.narkhede@gmail.com")
                .birthDate(LocalDate.now())
                .projectAssociation(4)
                .department(department1)
                .goalCnt(2)
                .build();
        Employee employee3 = Employee.builder().firstName("John").lastName("Kerr").email("john.kerr@gmail.com")
                .birthDate(LocalDate.now())
                .projectAssociation(5)
                .department(department1)
                .goalCnt(4)
                .build();
        employeeRepository.saveAll(Arrays.asList(employee, employee2, employee3));
    }
}

EmployeeController.java

@GetMapping("/employees/{searchValue}")
    public ResponseEntity<List<Employee>> findEmployees(@PathVariable("searchValue") String searchValue) {
        List<Employee> employees = employeeService.searchGlobally(searchValue);
        return new ResponseEntity<>(employees, HttpStatus.OK);
    }

EmployeeSpecification.java

public class EmployeeSpecification {
    public static Specification<Employee> textInAllColumns(Object value) {
        return (root, query, builder) -> builder.or(root.getModel().getDeclaredSingularAttributes().stream()
                .filter(attr -> attr.getJavaType().equals(value.getClass()))
                .map(attr -> map(value, root, builder, attr))
                .toArray(Predicate[]::new));
    }

    private static Object map(Object value, Root<?> root, CriteriaBuilder builder, SingularAttribute<?, ?> a) {
        switch (value.getClass().getSimpleName()) {
            case "String":
                return builder.like(root.get(a.getName()), getString((String) value));
            case "Integer":
                return builder.equal(root.get(a.getName()), value);
            case "LocalDate":
                return builder.equal(root.get(a.getName()), value);//date mapping
            default:
                return null;
        }
    }

    private static String getString(String text) {
        if (!text.contains("%")) {
            text = "%" + text + "%";
        }
        return text;
    }
}

When I hit the /employees/{searchValue}, I want searching to be happened in Department Table along with Employee table (may be using Joins something like that). Is that possible ? If yes, how can we do that ?

Or: Will this be good approach to put like here? Got reference from Using @Query

@Query("SELECT t FROM Todo t WHERE " +
            "LOWER(t.title) LIKE LOWER(CONCAT('%',:searchTerm, '%')) OR " +
            "LOWER(t.description) LIKE LOWER(CONCAT('%',:searchTerm, '%'))")
    List<Todo> findBySearchTerm(@Param("searchTerm") String searchTerm);

Any pointers?

Answer 1

If you take a look at my post actually I have a solution for join

@Override
public Specification<User> getFilter(UserListRequest request) {
    return (root, query, cb) -> {
        query.distinct(true); //Important because of the join in the addressAttribute specifications
        return where(
            where(firstNameContains(request.search))
                .or(lastNameContains(request.search))
                .or(emailContains(request.search))
        )
            .and(streetContains(request.street))
            .and(cityContains(request.city))
            .toPredicate(root, query, cb);
    };
}

private Specification<User> firstNameContains(String firstName) {
    return userAttributeContains("firstName", firstName);
}

private Specification<User> lastNameContains(String lastName) {
    return userAttributeContains("lastName", lastName);
}

private Specification<User> emailContains(String email) {
    return userAttributeContains("email", email);
}

private Specification<User> userAttributeContains(String attribute, String value) {
    return (root, query, cb) -> {
        if(value == null) {
            return null;
        }

        return cb.like(
            cb.lower(root.get(attribute)),
            containsLowerCase(value)
        );
    };
}

private Specification<User> cityContains(String city) {
    return addressAttributeContains("city", city);
}

private Specification<User> streetContains(String street) {
    return addressAttributeContains("street", street);
}

private Specification<User> addressAttributeContains(String attribute, String value) {
    return (root, query, cb) -> {
        if(value == null) {
            return null;
        }

        ListJoin<User, Address> addresses = root.joinList("addresses", JoinType.INNER);

        return cb.like(
            cb.lower(addresses.get(attribute)),
            containsLowerCase(value)
        );
    };
}

private String containsLowerCase(String searchField) {
    return "%" + searchField.toLowerCase() + "%";
}

Here you can see how I search the users by their address columns (city and street).

EDIT: Also you cannot use the @Query annotation that much dinamically (you van insert parameter values dinamically, but not parameters. That's where Specificaion is handy)

EDIT2: I know this is not the 2.x.x Spring version, but 1.5.x, but the idea is the same for joins.