使用Transformer时出现Hibernate异常PropertyNotFoundException [英] Hibernate exception PropertyNotFoundException when using Transformer

问题描述

我使用hibernate和hql来查询我的Java代码。但是我得到了这样的异常：

 原因：org.hibernate.PropertyNotFoundException：无法在类[我的班级] 
 at org.hibernate.property.ChainedPropertyAccessor.getSetter（ChainedPropertyAccessor.java:44）
  

我不明白0是什么意思。这里有一些与例子deatils：

我有几个表加入hql。这些表如下所示：

  A 
  -  A_ID 
  -  NAME 
 
 B 
  -  B_ID 
  -  A_ID 
 
 C 
  -  C_ID 
  -  B_ID 
  - 长度
  - 单位
  

课程：

  @Entity 
 @Table（name =A）
 class A 
 {
 @Id 
 @Column（name =A_ID，updatable = false ）
私人长ID; 
 
 @Column（name =NAME，nullable = false，length = 10，updatable = false）
私有字符串名称; 
 
 @OneToMany（mappedBy =a，fetch = FetchType.LAZY，cascade = {CascadeType.ALL}）
 @JoinColumn（name =A_ID，nullable = false）
私人套餐< B> BS; 
 
 @Transient 
私人双倍长度; 
 
 @Transient 
私人字符串单位; 
 
 // Setter and getters 
 ... 
} 
 
 @Entity 
 @Table（name =B）
 class B 
 {
 @Id 
 @Column（name =B_ID，updatable = false）
 private Long ID; 
 
 @ManyToOne 
 @JoinColumn（name =A_ID，nullable = false，insertable = true，updatable = false）
 private A a; 
 
 @OneToMany（mappedBy =b，fetch = FetchType.LAZY，cascade = {CascadeType.ALL}）
 @JoinColumn（name =B_ID，nullable = false）
私人套餐< C> CS; 
 
 // Setter and getters 
 ... 
} 
 
 @Entity 
 @Table（name =C）
 class C 
 {
 @Id 
 @Column（name =C_ID，updatable = false）
 private Long id; 
 
 @ManyToOne 
 @JoinColumn（name =B_ID，nullable = false，insertable = true，updatable = false）
 private B b; 
 
 @Column（name =LENGTH，nullable = false，updatable = false）
 private Double length; 
 
 @Column（name =UNIT，nullable = false，length = 10，updatable = false）
 private String unit; 
 
 // Setter and getters 
 ... 
} 
  

hql：

  select a，sum（c.length）as length，min（c.unit）as unit 
 from a a 
 left外部连接ab as b 
 left外部连接bc as c 
 group by 
 a.id 
 a.name 
  

查询：

  Query query = session.createQuery（hql.toString（））。setResultTransformer（Transformers.aliasToBean（A.class））; 
  

结果是收集了长度和单位的对象A的列表。我不明白为什么我得到这个例外。请给出一些建议。

---

更新：

一个ResultTransformer并输出所有别名来查看问题：

   - > 0 
  - >长度
  - >单位
  

除了长度和单位之外，它似乎将A视为A。我的HQL应该会出现一些问题吗？解决方案

<即使HQL可以正确转换为sql，但是当ResultTransformer得到结果时，结果中只有3个字段：

  1。 A 
 2.长度
 3.单位
  

无论有多少字段A，它们将被聚合成单个字段A，并且由于我没有为该字段设置任何别名，因此它将被视为字段0。

所以问题解决后，我改变了这样的HQL：

 选择a.id作为id，a.name作为名称， sum（c.length）作为长度，min（c.unit）作为单位
从A a 
离开外部连接ab作为b 
离开外部连接bc作为c 
 group by 
 a.id 
 a.name 
  

I'm using hibernate and hql for querying in my Java codes. But I got an exception like this:

Caused by: org.hibernate.PropertyNotFoundException: Could not find setter for 0 on class [my class]
    at org.hibernate.property.ChainedPropertyAccessor.getSetter(ChainedPropertyAccessor.java:44)

I don't understand what the "0" means. Here are some deatils with examples:

I have several tables joining hql. The tables are like this:

A
- A_ID
- NAME

B
- B_ID
- A_ID

C
- C_ID
- B_ID
- LENGTH
- UNIT

Classes:

@Entity
@Table(name="A")
class A
{
    @Id
    @Column(name="A_ID", updatable=false)
    private Long id;

    @Column(name="NAME", nullable=false, length=10, updatable=false)
    private String name;

    @OneToMany(mappedBy="a", fetch=FetchType.LAZY, cascade={CascadeType.ALL})
    @JoinColumn(name="A_ID", nullable=false)
    private Set<B> bs;

    @Transient
    private Double length;

    @Transient
    private String unit;

    // Setters and getters
    ...
}

@Entity
@Table(name="B")
class B
{
    @Id
    @Column(name="B_ID", updatable=false)
    private Long id;

    @ManyToOne
    @JoinColumn(name="A_ID", nullable=false, insertable=true, updatable=false)
    private A a;

    @OneToMany(mappedBy="b", fetch=FetchType.LAZY, cascade={CascadeType.ALL})
    @JoinColumn(name="B_ID", nullable=false)
    private Set<C> cs;

    // Setters and getters
    ...
}

@Entity
@Table(name="C")
class C
{
    @Id
    @Column(name="C_ID", updatable=false)
    private Long id;

    @ManyToOne
    @JoinColumn(name="B_ID", nullable=false, insertable=true, updatable=false)
    private B b;

    @Column(name="LENGTH", nullable=false, updatable=false)
    private Double length;

    @Column(name="UNIT", nullable=false, length=10, updatable=false)
    private String unit;

    // Setters and getters
    ...
}

hql:

select a, sum(c.length) as length, min(c.unit) as unit
from A a
left outer join a.b as b
left outer join b.c as c
group by
a.id
a.name

Query:

Query query = session.createQuery(hql.toString()).setResultTransformer(Transformers.aliasToBean(A.class));

The result is a list of object "A" with the length and unit collected. I don't understand why I got this exception. Please give some advices.

---

Update:

I wrote a ResultTransformer and output all the "alias" to see the problem:

-> 0
-> length
-> unit

It seems it treats the "A" besides with length and unit. There should be some problems with my HQL?

解决方案

Problem found:

Even if the HQL can be translated to sql correctly, but when ResultTransformer gets the result, there will be only 3 fields in the result:

1. A
2. length
3. unit

No matter how many fields in A, they will be aggregated into a single field "A" and since I didn't set any alias to this field, it will be treated as "field 0".

So the problem solved after I changed the HQL like this:

select a.id as id, a.name as name, sum(c.length) as length, min(c.unit) as unit
from A a
left outer join a.b as b
left outer join b.c as c
group by
a.id
a.name

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