JPA-PostgreSQL重复插入不报错

数据库PostgreSQL，持久化框架SpringData-JPA

从CrudRepository到SimpleJpaRepository的save方法

@Transactional
public  S save(S entity) {
    if(this.entityInformation.isNew(entity)) {
        this.em.persist(entity);
        return entity;
    } else {
        return this.em.merge(entity);
    }
}

看到CrudRepository有两个主要的实现类，SimpleJpaRepository和SimpleKeyValueRepository

 

 

走到SimpleJpaRepository的save方法，然后走JpaMetamodelEntityInformation的isNew

public boolean isNew(T entity) {
    if(this.versionAttribute != null && !this.versionAttribute.getJavaType().isPrimitive()) {
        BeanWrapper wrapper = new DirectFieldAccessFallbackBeanWrapper(entity);
        Object versionValue = wrapper.getPropertyValue(this.versionAttribute.getName());
        return versionValue == null;
    } else {
        return super.isNew(entity);
    }
}

然后走super.isNew(),就是AbstractEntityInformation的isNew

 

public boolean isNew(T entity) {
    ID id = this.getId(entity);
    Class idType = this.getIdType();
    if(!idType.isPrimitive()) {
        return id == null;
    } else if(id instanceof Number) {
        return ((Number)id).longValue() == 0L;
    } else {
        throw new IllegalArgumentException(String.format("Unsupported primitive id type %s!", new Object[]{idType}));
    }
}

this是JpaMetamodelEntityInformation；this.getIdType()在我这个实例中等于RelationCompositeKey，实体entity上使用@IdClas注解 ；而RelationCompositeKey没有实现isPrimitive()返回false，isNew返回false，所以最后走了meger方法。

贴部分实体代码
@IdClass(RelationCompositeKey.class)
public final class RelationEntity implements ToData {

    @Id
    @Column(name = RELATION_FROM_ID_PROPERTY)
    private String fromId;
    
    
@Data
public class RelationCompositeKey implements Serializable {

    @Transient
    private static final long serialVersionUID = -4089175869616037592L;

    private String fromId;
    private String fromType;