对于repository.save（entityModel），Hibernate OneToMany关联表字段不能为null

Question

There are two entity Policy and PolicyDetails. Policy.id is one to many associated with PolicyDetails.policyId. like

@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name = "policy_id", referencedColumnName = "id")
private List<PolicyDetails> policyDetails;

When i GET the data all are ok. But i run policyRepository.save(policy) throw below error-

Hibernate: update policy set category_id=?, category_name=?, client_id=?, summary=? where id=? Hibernate: update policy_details set policy_id=null where policy_id=? and id=? Hibernate: update policy_details set policy_id=null where policy_id=? and id=?

Caused by: java.sql.BatchUpdateException: Column 'policy_id' cannot be null Caused by: java.sql.SQLIntegrityConstraintViolationException: Column 'policy_id' cannot be null

@Entity
@Data
@Table(name = DBTables.POLICY)
public class Policy implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false, updatable = false)
    private Integer Id;

    @Column(name = "summary")
    @NotNull(message = ErrorCode.SUMMARY_NOT_FOUND)
    private String summary;

    @Column(name = "category_id")
    @NotNull(message = ErrorCode.CATEGORY_ID_NOT_FOUND)
    private Integer categoryId;

    @Column(name = "category_name")
    @NotNull(message = ErrorCode.CATEGORY_NAME_NOT_FOUND)
    private String categoryName;

    @Column(name = "client_id")
    @NotNull(message = ErrorCode.CLIENT_ID_NOT_FOUND)
    private Integer clientId;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "policy_id", referencedColumnName = "id")
    private List<PolicyDetails> policyDetails;
}

@Entity
@Data
@Table(name = DBTables.POLICY_DETAILS)
public class PolicyDetails implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false, updatable = false)
    private Integer id;

    @Column(name = "policy_id")
    @NotNull(message = ErrorCode.POLICY_ID_NOT_FOUND)
    private Integer policyId;

    @Column(name = "period")
    @NotNull(message = ErrorCode.PERIOD_NOT_FOUND)
    private String period;

    @Column(name = "logic_id")
    @NotNull(message = ErrorCode.LOGIC_ID_NOT_FOUND)
    private Integer logicId;

    @Column(name = "logic_value")
    @NotNull(message = ErrorCode.LOGIC_VALUE_NOT_FOUND)
    private Integer logicValue;

    @Column(name = "policy_type_id")
    @NotNull(message = ErrorCode.POLICY_TYPE_ID_NOT_FOUND)
    private Integer policyTypeId;
}

    public String saveRegisterPolicy(PolicyRequestDto policyRequestDto, Integer userId) {

        Policy policy = new Policy();

        policy.setId(policyRequestDto.getId());
        policy.setSummary(policyRequestDto.getSummary());
        policy.setCategoryId(policyRequestDto.getCategoryId());
        policy.setCategoryName(policyRequestDto.getCategoryName());
        policy.setClientId(userId);

        List<PolicyDetails> policyDetails = new ArrayList<>();
        policyDetails.addAll(policyRequestDto.getCancelPolicies());
        policyDetails.addAll(policyRequestDto.getDelayPolicies());

        policyDetails.forEach(eachPolicyDetails ->
            eachPolicyDetails.setPolicyId(policyRequestDto.getId())
        );

        policy.setPolicyDetails(policyDetails);

        policyRepository.save(policy);


        return null;
    }

Answer 1

You are very close, however, your mapping is a little bit wrong. In hibernate, we must have the object (not an id) for the mapping. And the relationship is recommended to be bidirectional, for both: usability and speed. Hibernate will create awkward queries with the unidirectional many-to-one and one-to-many relationships in some cases.

    @NotNull(message = ErrorCode.POLICY_ID_NOT_FOUND)
    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "policy_id", referencedColumnName = "id", nullable = false)
    private Policy policy;

So change your PolicyDetails to be:

@Entity
@Data
@Table(name = DBTables.POLICY_DETAILS)
public class PolicyDetails implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false, updatable = false)
    private Integer id;

    @NotNull(message = ErrorCode.POLICY_ID_NOT_FOUND)
    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "policy_id", referencedColumnName = "id", nullable = false)
    private Policy policy;

    @Column(name = "period")
    @NotNull(message = ErrorCode.PERIOD_NOT_FOUND)
    private String period;

    @Column(name = "logic_id")
    @NotNull(message = ErrorCode.LOGIC_ID_NOT_FOUND)
    private Integer logicId;

    @Column(name = "logic_value")
    @NotNull(message = ErrorCode.LOGIC_VALUE_NOT_FOUND)
    private Integer logicValue;

    @Column(name = "policy_type_id")
    @NotNull(message = ErrorCode.POLICY_TYPE_ID_NOT_FOUND)
    private Integer policyTypeId;
}