java - 复合 key 不会由相应的ID填充

这是CampaignEntity.class实体：

@Entity
@Table(name = "campaign")
public class CampaignEntity implements Serializable {

    @Id
    @SequenceGenerator(name = "campaign_id_gen", sequenceName = "campaign_seq", initialValue = 1, allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "campaign_id_gen")
    private Long id;

    @OneToMany(cascade = CascadeType.REMOVE, mappedBy = "campaignId", fetch = FetchType.EAGER, targetEntity = CampaignCountry.class)
    private List<CampaignCountry> countries;

    @Column(name = "include_countries")
    private Boolean includeCountries;

    // getters & setters, toString, hashEquals
}

这是我要映射的CampaignCountry.class：

@Entity
@Table(name = "campaign_country")
@IdClass(CampaignCountry.CampaignCountryPK.class)
public class CampaignCountry {
    @Id
    @Column(name="campaign_id")
    private Long campaignId;
    @Id
    @Column(name="country")
    private String country;

    public CampaignCountry(String country) {
        this.country = country;
    }

    //getters and setters

    static class CampaignCountryPK implements Serializable {

        private Long campaignId;

        private String country;

        public CampaignCountryPK() {}

        public CampaignCountryPK(Long campaignId, String country) {
            this.campaignId = campaignId;
            this.country = country;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            CampaignCountryPK that = (CampaignCountryPK) o;

            if (campaignId != null ? !campaignId.equals(that.campaignId) : that.campaignId != null) return false;
            return country != null ? country.equals(that.country) : that.country == null;
        }

        @Override
        public int hashCode() {
            int result = campaignId != null ? campaignId.hashCode() : 0;
            result = 31 * result + (country != null ? country.hashCode() : 0);
            return result;
        }
    }
}

当我打电话给repository.saveAndFlush(campaignEntity)时，问题就来了。它可以根据需要保存国家/地区，但不能保存CampaignId。它始终为空。


  org.springframework.orm.jpa.JpaObjectRetrievalFailureException：无法找到ID为domain.CampaignCountry的domain.CampaignCountry$CampaignCountry$CampaignCountryPK@e43;
  
  嵌套异常为javax.persistence.EntityNotFoundException：无法找到ID为domain.CampaignCountry$CampaignCountryPK@e43的domain.CampaignCountry


这是迁移SQL脚本（如果它与任何事情有关）：

CREATE TABLE campaign_country (
  campaign_id BIGINT               NOT NULL,
  country     CHARACTER VARYING(2) NOT NULL,
  PRIMARY KEY (campaign_id, country)
);

ALTER TABLE campaign_country
  ADD CONSTRAINT campaign_to_campaign_country FOREIGN KEY (campaign_id) REFERENCES campaign (id);

那么，这里出了什么问题，如何用相应的campaignEntity的ID填充campaignId？我确实相信@OneToMany注释中有一些内容，可能无法正确实现。

最佳答案

改用@EmbeddedId怎么样？

@Entity
public class CampaignCountry implements Serializable {

    @EmbeddedId
    private CampaignCountryPK id;

    @MapsId("campaignId")
    @ManyToOne
    @JoinColumn(name = "campaign_id")
    private CampaignEntity campaignEntity;
}

@Embeddable
public class CampaignCountryPK implements Serializable {

    @Column(name = "campaign_id")
    private long campaignId;
    @Column(name = "country")
    private String country;
}

@Entity
@Table(name = "campaign_country")
public class CampaignCountry implements Serializable {

    @EmbeddedId
    private CampaignCountryPK id;

    @MapsId("campaignId")
    @ManyToOne
    @JoinColumn(name = "campaign_id")
    private CampaignEntity campaignEntity;
}

然后在CampaignEntity中将映射更改为：

@OneToMany(cascade = CascadeType.ALL, mappedBy = "campaignEntity", fetch = FetchType.EAGER, targetEntity = CampaignCountry.class)
private List<CampaignCountry> countries;

您只需将对象创建为：

List<CampaignCountry> countryList = new ArrayList<>();
CampaignEntity campaign = new CampaignEntity();

CampaignCountryPK pk1 = new CampaignCountryPK();
pk1.setCountry("Country 1");
CampaignCountry country1 = new CampaignCountry();
country1.setId(pk1);
country1.setCampaignEntity(campaign);

countryList.add(country1);
campaign.setCountries(countryList);

或者，您可以创建一种创建PK的方法。