java - 同一实体中对另一个实体的两次引用

Question

我有实体User，该实体在另一个实体Product中使用了两次。我使用 hibernate 并创建表之间的外键。还有两个外键 - 用于create_by 和modified_by。

用户类

class User {

    private Set<Product> products = new HashSet<Product>(0);

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "user")
    public Set<ProductgetProducts{
        return this.products
    }

    public void setProducts(Set<Product> products) {
        this.products = products
    }
}

类产品

class Product {
    private User createdBy;
    private User modifiedBy;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
    @JoinColumn(name = "modified_by", nullable = false)
    public User getModifiedBy() {
        return modifiedBy;
    }

    public void setModifiedBy(User createdBy) {
        this.modifiedBy= modifiedBy;
    }

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
    @JoinColumn(name = "created_by", nullable = false)
    public User getCreatedBy() {
        return createdBy;
    }

    public void setCreatedBy(User createdBy) {
        this.createdBy = createdBy;
    }
}

它向我抛出了这个异常，但我不知道如何修复它。

Caused by: org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: Product.user in User.products

Answer 1

mappedBy = "user"意思是:我是双向关联的反面，其所有者方是目标实体(即Product)中的字段user 。产品中没有 user 字段。所以这没有意义。

如果您希望 createdBy 广告 modifiedBy 关联是双向的，则在 User 中需要两个字段:

@OneToMany(mappedBy = "createdBy")
private Set<Product> createdProducts;

@OneToMany(mappedBy = "modifiedBy")
private Set<Product> modifiedProducts;