如何在不自动创建表的情况下生成实体类

Question

我为我的系统创建了一些报告，该报告由许多表组成。为此，我创建了一个带有@Entity注释的域类，并实现了一个JpaRepository存储库，我将本机查询与@query一起使用，如下所示。

我的问题是，对于每个域类，hibernate都在创建一个表，如何停止它？

我的域类：

@Entity
@Immutable
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@IdClass(WidgetDailyReportCompositeKey.class)
public class WidgetDailyReportDomain{

    @Id
    @Column(updatable = false, insertable = false)
    private UUID id_construction;

    @Id
    @Column(updatable = false, insertable = false)
    private String name;

    @Id
    @Column(updatable = false, insertable = false)
    private Date dt_cost;

    @Column(updatable = false, insertable = false)
    private Double total;
}

我的存储库：

public interface WidgetRepository extends JpaRepository<WidgetDailyReportDomain, UUID>{

    @Query(value =  "     SELECT ct.id AS id_construction,                                                                                              " +
                    "            ct.name,                                                                                                               " +
                    "            sm.dt_service AS dt_cost,                                                                                              " +
                    "            sum(smi.nu_value * stiv.amount) AS total                                                                               " +
                    "       FROM service_measurement sm                                                                                                 " +
                    " INNER JOIN service_measurement_item smi   ON smi.id_service_measurement = sm.id                                                   " +
                    " INNER JOIN service s                      ON s.id                       = sm.id_service                                           " +
                    " INNER JOIN service_type_item_service stiv ON stiv.id_service            = sm.id_service                                           " +
                    "                                          AND stiv.id_service_type_item = smi.id_service_item                                      " +
                    " INNER JOIN construction ct                ON ct.id                      = s.id_construction                                       " +
                    "      WHERE s.id_construction IN (                                                                                                 " +
                    "                                   select s.id_construction                                                                        " +
                    "                                   from service_measurement sm                                                                     " +
                    "                                   INNER JOIN service_measurement_item smi   ON smi.id_service_measurement = sm.id                 " +
                    "                                   INNER JOIN service s                      ON s.id                       = sm.id_service         " +
                    "                                   INNER JOIN service_type_item_service stiv ON stiv.id_service            = sm.id_service         " +
                    "                                                                            AND stiv.id_service_type_item  = smi.id_service_item   " +
                    "                                   INNER JOIN construction ct                on ct.id                      = s.id_construction     " +
                    "                                   WHERE sm.dt_service BETWEEN :minDate AND :maxDate                                               " +
                    "                                   GROUP BY s.id_construction                                                                      " +
                    "                                   ORDER BY sum(smi.nu_value * stiv.value) DESC                                                    " +
                    "                                   limit :limit                                                                                    " +
                    "       )                                                                                                                           " +
                    "       AND sm.dt_service BETWEEN :minDate AND :maxDate                                                                             " +
                    "  GROUP BY ct.id, sm.dt_service                                                                                                    " +
                    "    HAVING sum(smi.nu_value * stiv.amount) > 0                                                                                     " +
                    "  ORDER BY sm.dt_service;", nativeQuery = true)
    List<WidgetDailyReportDomain> findTopExpensiveConstruction(@Param("minDate") Date minDate, @Param("maxDate") Date maxDate, @Param("limit") int limit);

//....

Answer 1

由于您的问题中有一个假设，您似乎正在使用Spring。

如果您使用的是Spring Boot，那么您可以添加

spring:
  jpa:
    hibernate:
      ddl-auto: none

到您的application.yml文件，或

spring.jpa.hibernate.ddl-auto=none

到您的应用程序。属性文件。

如果您使用的是持久性。xml文件，您也可以在其中添加属性以禁用它：

<property name="hibernate.hbm2ddl.auto" value="none"/>

但是，禁用这样的模式表的生成意味着您必须确保在应用程序正常工作之前通过其他方式创建它们。

Answer 2

您可以删除所有的javax.persistence注释，如@Col列、@Id、@Entity。这些注释表示表的属性，您似乎不希望它是这样。

然后，可以使用WidgetDailyReportDomain对象作为DTO作为投影，而不将其附加到EntityManager：https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#projections.dtos

编辑：另外，不要忘记为该对象构建构造函数，以便Spring JPA将值加载到该对象中（如文档中所述）。如果不想构建构造函数，可以将其更改为接口并将其用作投影：https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#projections.interfaces

Answer 3

您的WidgetDailyReportDomain实际上是投影。您不需要将其标记为@实体。您的@查询可能属于任何其他真正现有的存储库。