在关联实体中使用规范 Spring Data Jpa 进行多列搜索？

Question

我将这个问题 Perform multi column search on Date, Integer and String Data type fields of Single Table? 和 This method must return a result of type Specification<Employee> in Java 8 更进一步。

实际上，我想在关联实体中进行搜索以及全局搜索的一部分。使用JPA 2 Specifications API 可以实现吗？

我有Employee 和Department @OneToMany bi-directional 关系。

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;
}

部门.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;
}

我保存了如下数据。 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;
    }
}

当我点击/employees/{searchValue} 时，我希望在Department 表和Employee 表中进行搜索（可能使用Joins 类似的东西）。那可能吗 ？如果是，我们该怎么做？

或者： 这会是像这里这样放置的好方法吗？从Using @Query得到参考

@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);

任何指针？

Answer 1

如果你看看我的post，其实我有一个加入的解决方案

@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() + "%";
}

在这里您可以看到我如何通过地址列（城市和街道）搜索用户。

编辑：您也不能以动态方式使用@Query 注释（您可以动态地插入参数值，但不插入参数。这就是 Specificationaion 很方便的地方）

EDIT2：我知道这不是 2.x.x Spring 版本，而是 1.5.x，但连接的想法是一样的。