Spring JPA 具有嵌套关系，但只需要 1 个深度关系

Question

我为

MainBranch

模型制作了 2 个深度关系，当我得到

MainBranch

时，它将得到

SubBranch

和

SubBranchRef

。我需要得到

MainBranch

和

SubBranch

。对于这个问题我该怎么办？

public class MainBranch{

    @Column(name = "name", nullable = false, length = 100)
    private String name;

    @OneToMany(mappedBy = "mainBranch")
    @JsonManagedReference
    private List<SubBranch> subBranchs = new ArrayList<>();
}


public class SubBranch{
    @Column(name = "name", nullable = false, length = 100)
    private String name;

    @ManyToOne
    @JsonBackReference
    @JoinColumn(name = "main_branch_id", nullable = false)
    private MainBranch mainBranch;

    @OneToMany(mappedBy = "subBranch")
    @JsonManagedReference
    private List<SubBranchRef> subBranchRef = new ArrayList<>();

}

public class SubBranchRef{

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "sub_branch_id", nullable = false)
    @JsonBackReference
    private SubBranch subBranch;

    @Column(name = "ref_data", nullable = false, length = 200)
    private String refData;

}

Answer 1

也许可以在

FetchType.LAZY

中使用

SubBranchRef

代替

SubBranch entity

:

通过将 FetchType 设置为 LAZY，当我们获取

SubBranchRef

时，不会加载

SubBranch

。

public class SubBranch{
    ...
    @OneToMany(mappedBy = "subBranch", fetch = FetchType.LAZY)
    @JsonManagedReference
    private List<SubBranchRef> subBranchRef = new ArrayList<>();
    ...
}