使用Hibernate公式从另一个表中选择一个实体 [英] Selecting an entity from another table using a Hibernate formula

问题描述

我试图用Hibernate的@Formula注解从另一个表中检索一个实体。给出以下代码：

I'm attempting to retrieve an entity from another table using Hibernate's @Formula annotation. Given the following code:

@Entity
class Test {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", updatable = false, nullable = false)
    private Long id = null;

    // ...

    @Formula("(SELECT r FROM Result r WHERE test_id = id AND resultDate = (SELECT MAX(resultDate) FROM Result WHERE test_id = id))")
    private Result lastestResult;

    // ...

    public Result getLatestResult() {
        return latestResult;
    }

    // ...
}

<

The Result class looks like this:

@Entity
class Result {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", updatable = false, nullable = false)
    private Long id = null;

    @ManyToOne
    private Test test;

    // ...
}

但是在尝试加载一个测试实体，我收到错误列TEST0_.RESULTDATE未找到。我尝试了其他一些涉及@JoinFormula注释的事情，但没有取得任何成功。我也遇到了这个答案，这似乎表明我正在做的事情应该工作，但事实并非如此。如何使这项工作成功？

But upon attempting to load a Test entity, I'm getting the error 'Column "TEST0_.RESULTDATE" not found'. I've tried a few other things as well involving the @JoinFormula annotation, but without any success. I also came across this answer, which seems to indicate that what I'm doing should work, but it doesn't. How do I make this work?

推荐答案

所以，我找到了解决这个问题的解决方案。 latestResult 属性的注释如下：

So, I've found the solution to this particular problem. Annotations on the latestResult property are as follows:

@ManyToOne
@JoinColumnsOrFormulas({
    @JoinColumnOrFormula(formula=@JoinFormula(value="(SELECT r.id FROM Result r WHERE resultDate = (SELECT MAX(sqr.resultDate) FROM Result sqr WHERE sqr.test_id = id))", referencedColumnName="id")),
})
private Result latestResult;

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