@MappedSuperclass 和实现 table

Question

我继承了一些非常糟糕的代码，我希望对其进行重构以提高可重用性。有一组报告 table，主要由 3 列组成：id、report_type_fk 和 report_description。我想将所有报告 table 合并为一个以便于使用。

我正在重构代码，我认为最好将我们当前的实体分解，这样 Report 是一个具有 type 实现的抽象 class。例如DmvReport extends Report、CreditScoreReport extends Report等

我运行遇到的问题是只有 1 个报告 table 所有实体都需要保存到。有没有办法让 abstract Report 对象的所有具体实现都保存到同一个 table?

这是我继承的错误代码的示例

举报class

@Entity
@Table(name = "report")
public class Report<E extends Exception> {
    private long id;
    private ReportType type;
    private String description;
   ...
   ...
}

信用报告class

@Entity
@Table(name = "credit_report")
public class CreditScore Report<E extends Exception> extends Report<E> {
    private long id;
    private ReportType type;
    private String description;
   ...
   ...
}

我想把它变成：

@MappedSuperclass
@Table(name = "report")
public abstract class Report<E extends Exception> {
    @Id @Column(name="id")
    private long id;

    @OneToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "report_type_id")
    private ReportType type;

    @column(name="description")
    private String description;
   ...
   ...
}

@Entity
@Table(name = "report")
public class CreditScoreReport<E extends Exception> extends Report<E> {

   public void doCreditScoreStuff(){
      ...
   }
}

@Entity
@Table(name = "report")
public class DmvReport<E extends Exception> extends Report<E> {
   public void doDmvStuff(){
      ...
   }
}

Answer 1

我认为你应该使用 @Inheritance 而不是 @MappedSuperClass。您的代码将如下所示：

@Entity
@Table(name = "report")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "report_type_id", discriminatorType = DiscriminatorType.INTEGER)
public abstract class Report<E extends Exception> {
    @Id @Column(name="id")
    private long id;

    @column(name="description")
    private String description;
   ...
   ...
}

@Entity(name = "CreditScoreReport")
@DiscriminatorValue("1") // the id corresponding to the credit score report
public class CreditScoreReport<E extends Exception> extends Report<E> {

   @Column(name = "specific_credit_score_report_1)
   private Integer specificCreditScoreReport1;

   public void doCreditScoreStuff(){
      ...
   }
}

@Entity(name = "DmvReport")
@DiscriminatorValue("2") // the id corresponding to the DMV report
public class DmvReport<E extends Exception> extends Report<E> {

   @Column(name = "specific_dmv_score_report_1)
   private Integer specificDmvScoreReport1;

   public void doDmvStuff(){
      ...
   }
}

此策略允许您将信用评分报告和 DMV 报告数据存储在一个 table (report) 中，但根据 report_value_id 字段实例化适当的实体。您不必在参数中定义 report_value_id，因为它已用于创建所需的实体。

这是您要找的吗？

@MappedSuperclass 和实现 table

@MappedSuperclass and implementation table

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