Java PropertyAccessException：无法通过反射获取器获取字段值
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PropertyAccessException: could not get a field value by reflection getter
提问by Wit Mesh
I have a many to one mapping with two classes (code is reduced):
我有两个类的多对一映射（代码减少了）：
Category:
类别：
@Entity
public class Category {
@Id
@Column(name = "CATEGORY_ID")
Long id;
@NotNull
String name;
Subcategory:
子类别：
@Entity
public class Subcategory {
@Id
@Column(name = "SUBCATEGORY_ID")
Long id;
@NotNull
@ManyToOne(targetEntity = Category.class)
@JoinColumn(name = "CATEGORY_ID")
Long categoryId;
@NotNull
String name;
When I try to add subcategory to existing category, I get
当我尝试将子类别添加到现有类别时，我得到
ERROR [org.jboss.ejb3.invocation] JBAS014134: EJB Invocation failed on component SubcategoryController for method public void %package%.SubcategoryController.add(%package%.Subcategory): javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of %package%.Category.id
...
at %package%.SubcategoryController$$$view1.add(Unknown Source)
...
at %package%.SubcategoryController$Proxy$_$$_Weld$Proxy$.add(SubcategoryController$Proxy$_$$_Weld$Proxy$.java)
at %package%.SubcategoryService.add(SubcategoryService.java:30)
at %package%.SubcategoryService$Proxy$_$$_WeldClientProxy.add(SubcategoryService$Proxy$_$$_WeldClientProxy.java)
...
Caused by: javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of %package%.Category.id
What should I do to awoid this error?
我应该怎么做才能避免这个错误？
回答by Dragos Stratulat
In your category class it should be an OneToMany annotation like this :
在您的类别类中，它应该是这样的 OneToMany 注释：
@Entity
public class Category {
@Id
@Column(name = "CATEGORY_ID")
Long id;
@NotNull
String name;
@OneToMany(mappedBy = "category")
List<Subcategory> subcategories;
}
You might also want to check out:
www.mkyong.com/hibernate/hibernate-one-to-many-relationship-example-annotation/
您可能还想查看：
www.mkyong.com/hibernate/hibernate-one-to-many-relationship-example-annotation/
回答by Alexandru Severin
Situations where this exception might occur:
可能发生此异常的情况：
1)name of database table is incorrect or missing:
1)数据库表名不正确或缺失：
@Entity
@Table(name = "category_table") // name of database table
public class Category
2)Field class doesn't match the target class:
2)字段类与目标类不匹配：
@ManyToOne(targetEntity = Category.class) // Target class
@JoinColumn(name = "CATEGORY_ID")
Category categoryId; // Target field
In your case categoryIdis of type Long, and hibernate is trying to insert Category.classfields into categoryIdbut can't.
在您的情况下categoryId是 type Long，并且 hibernate 试图将Category.class字段插入categoryId但不能。
