n+1 问题与延迟加载一对一关系

Question

My Question is when an null ability occur in one to one relation even my child class Primary Key same like parent class Primary Key So when Insert @PrimaryKeyJoinColumn on one to one relation in Insertion I have seen below Link Issue not-null property references a null or transient value in one to one relation

and when i Remove this tag n+1 issue resolved...so how can i resolved it Please Help

private SiteSecurity siteSecurity;
private SiteDetails details;
private SiteAvr avr;
private SiteRectifier rectifier;

@OneToOne( fetch = FetchType.LAZY, mappedBy = "site")
@PrimaryKeyJoinColumn

in Parent Class Fields regarding one to one relations

    @GenericGenerator(name = "generator", strategy = "foreign", parameters = @Parameter(name = "property", value = "site"))
@Id
@GeneratedValue(generator = "generator")
@Column(name = "id", unique = true, nullable = false)
public Integer getId() {
    return this.id;
}

public void setId(Integer id) {
    this.id = id;
}

@OneToOne(fetch = FetchType.LAZY)
@PrimaryKeyJoinColumn
public Site getSite() {
    return site;
}

public void setSite(Site site) {
    this.site = site;
}

this is child class so how can i resolved both issue not null and n+1

Answer 1

Simply set optional=true in your OneToOne relationship like:

@OneToOne(fetch = FetchType.LAZY, optional=true)
@PrimaryKeyJoinColumn
public Site getSite() {
    return site;
}

Answer 2

To avoid the n+1 Problem ensure the one to one relationship in sync with the other table if Site Table has a row so another one to one relation table has a row against them and this annotation @PrimaryKeyJoinColumn is on them...

In My case, this strategy will work to avoid the n+1 problem

Please Got through this Like is also Briefly elaborate the One to One Relation Post