[英]Hibernate: Unique constraint for list of Embeddables (@ElementCollection)
Given an Enitiy Product
给定一个实体
Product
@Entity
public class Product {
private Long id;
private List<Review> reviews;
public Product() {}
@Id
@GeneratedValue
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
@ElementCollection
public List<Review> getReviews() {
return reviews;
}
public void setReviews(List<Review> reviews) {
this.reviews = reviews;
}
// equals() and hashCode() omitted for brevity
}
And an Embeddable Review
和可嵌入的
Review
@Embeddable
public class Review {
private Customer author;
private String title;
private String comment;
public Review() {}
@ManyToOne(optional = false)
@Column(unique = true)
public Customer getAuthor() {
return author;
}
public void setAuthor(Customer author) {
this.author = author;
}
@Column(nullable = false)
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
@Column(nullable = false, length = 2000)
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
}
How can I set an unique constraint for the Review
's author.如何为
Review
的作者设置唯一约束。 In other words: I want to make sure, that for a given product each review has a different author.换句话说:我想确保对于给定的产品,每条评论都有不同的作者。
Can I use @NaturalId
?我可以使用
@NaturalId
吗? Do I use @Column(unique = true)
?我使用
@Column(unique = true)
吗? I already found a similar question on StackOverflow , but in my case it's a list of Embeddables and not just a member, so that that approach won't work, I guess.我已经在 StackOverflow 上发现了一个类似的问题,但在我的情况下,它是一个 Embeddables 列表,而不仅仅是一个成员,所以我猜这种方法是行不通的。
Thanks a lot in advance!非常感谢!
If you are talking about having a unique database index added during schema generation then you can do this as below:如果您正在谈论在模式生成期间添加唯一的数据库索引,那么您可以执行以下操作:
@ElementCollection
@CollectionTable(name = "product_reviews",
uniqueConstraints = {@UniqueConstraint(columnNames={"product_id", "author_id"})})
public List<Review> getReviews() {
return reviews;
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.