java @JoinFormula 和 @OneToMany 定义 - 糟糕的文档
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@JoinFormula and @OneToMany definition - poor documentation
提问by Vojtěch
I have two questions concerning @JoinFormula and @OneToMany annotations:
我有两个关于 @JoinFormula 和 @OneToMany 注释的问题：
How can I limit the number of result with
@JoinFormulaand@OneToManyannotations?How can I define that
idin expressionauthor = idrefers toAuthor.id?Author { @Id private Long id; @OneToMany @JoinFormula(value = "SELECT a FROM Article a WHERE author = id AND schedule < CURRENT_TIMESTAMP()") // limit = 15 private List<Article> pastArticles; }
如何限制结果
@JoinFormula和@OneToMany注释的数量？我如何定义
id在表达式author = id中指的是Author.id？Author { @Id private Long id; @OneToMany @JoinFormula(value = "SELECT a FROM Article a WHERE author = id AND schedule < CURRENT_TIMESTAMP()") // limit = 15 private List<Article> pastArticles; }
Like this, I keep having the pastArticles empty, even when I remove the schedule <part of the clause.
像这样，即使我删除schedule <了子句的一部分，我仍然让过去的文章为空。
Thanks!
谢谢！
采纳答案by Jubin Patel
Answer 1 :
答案 1：
@Size(max=10)
private List<Comment> commentList;
Answer 2 :(just example like that)
答案 2 :(只是这样的例子）
public class A{
@Id
@GeneratedValue
private Integer id;
private String uuid;
...
}
other class
其他班级
public class B{
@Id
@GeneratedValue
private Integer id;
private String uuidOfA;
@ManyToOne
@JoinColumnsOrFormulas({
@JoinColumnOrFormula(formula=@JoinFormula(value="(SELECT a.id FROM A a WHERE a.uuid = uuid)", referencedColumnName="id")),
@JoinColumnOrFormula(column = @JoinColumn("uuidOfA", referencedColumnName="uuid"))
})
private A a;
}
回答by Micha Roon
you'd be better off using the @Whereannotation to limit the results
你最好使用@Where注释来限制结果
