英文:
How to use child table column in org.hibernate.annotations.Formula
问题
我需要使用 `@Formula` 来连接父表和子表的某些列。以下是实体类的示例代码：@Entity@Table(name = "parent1")public class Parent1 implements Serializable {@Idprivate BigInteger id;@Column(name = "childId")private BigInteger childId;@Column(name = "col1")private String col1;@Column(name = "col2")private String col2;@Formula("CONCAT_WS(' ', (SELECT p2.child_colm FROM parent2 p2 WHERE p2.childId = childId), col1, col2)")private String combinedName;@OneToOne@JoinColumn(name = "childId")private Parent2 parent2;}@Entity@Table(name = "parent2")public class Parent2 implements Serializable {@Id@Column(name = "childId")private BigInteger childId;@Column(name = "child_colm")private String child_colm;}
在这样的情况下，会返回 Unknown column 'Parent2.child_colm' 的错误。
英文:
I need to concat some columns from both parent and child table using @Formula
Here is the Entities
@Entity@Table(name = "parent1")public class Parent1 implements Serializable {@Idprivate BigInteger id;@Column(name = "childId")private BigInteger childId;@Column(name = "col1")private String col1;@Column(name = "col2")private String col2;@Formula("CONCAT_WS(' ',Parent2.child_colm,col1,col2)")private String combinedName;@OneToOne@JoinColumn(name = "childId")private Parent2 parent2;}@Entity@Table(name = "parent2")public class Parent2 implements Serializable {@Id@Column(name = "childId")private BigInteger childId;@Column(name = "child_colm")private String child_colm;}
While giving like this it returns Unknown column 'Parent2.child_colm'
答案1
得分: 1
我建议您不要在这里使用 @Formula，而只需编写以下方法：
import javax.persistence.Transient;@Entity@Table(name = "parent1")public class Parent1 implements Serializable {@Transientpublic String getCombinedName() {return Stream.of(parent2.child_colm, col1, col2).filter(s -> s != null && !s.isEmpty()).collect(Collectors.joining(" "));}}
@Transient 注释 用于指定不应持久化给定的实体属性。
英文:
I would suggest you instead of using @Formula here just write the following method:
import javax.persistence.Transient;@Entity@Table(name = "parent1")public class Parent1 implements Serializable {@Transientpublic String getCombinedName() {return Stream.of(parent2.child_colm, col1, col2).filter(s -> s != null && !s.isEmpty()).collect(Collectors.joining(" "));}}
The @Transient annotation is used to specify that a given entity attribute should not be persisted.
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