java实体管理器批量更新提供了组织。冬眠PersistentObjectException:传递给persist的分离实体
我试图遵循this article,因为通过批量更新,我会使用merge获得不必要的选择:
for(int i = 0; i< elements.size(); i++){
Query q = em.createQuery("select p from Parent p join fetch p.child c where p.id=:id", Parent.class);
//parameter of :id from elements
Parent p = q.getSingleResult();
p.setName("aname"); //for simplicity just the name member
myList.add(p);
}
utx = com.arjuna.ats.jta.UserTransaction.userTransaction();
utx.begin();
em.joinTransaction();
for(int i = 0; i< myList.size(); i++){
if (i > 0 && i % Common.BATCH_SIZE == 0) { //BATCH_SIZE=50
em.flush();
em.clear();
}
Parent myObject = myList.get(i);
em.merge(myObject);
}
utx.commit();
这是我的实体定义:
@Entity
@Table(name = "myparenttable", schema = "myschema", catalog = "mydb")
@JsonIgnoreProperties(ignoreUnknown = true)
public class Parent implements Serializable {
private Integer id_parent;
private String name;
@JsonManagedReference
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
private List<Child> children;
//getters and setters
@JsonInclude(JsonInclude.Include.NON_NULL)
@OneToMany(mappedBy = "parent", targetEntity = Child.class, fetch = FetchType.LAZY,cascade = {CascadeType.PERSIST, CascadeType.MERGE})
public Set<Child> getChildren() {
return this.children;
}
public void setChildren(Set<Child> children) {
this.children = children;
}
}
@Entity
@Table(name = "mychildtable", schema = "myschema", catalog = "mydb")
public class Child implements Serializable {
private Integer id_child;
private String description;
@JsonBackReference
private Parent parent;
//getters and setters
}
根据上面提到的文章,我修改了代码如下:
utx = com.arjuna.ats.jta.UserTransaction.userTransaction();
utx.begin();
em.joinTransaction();
Session session = em.unwrap( Session.class );
for(int i = 0; i< myList.size(); i++){
if (i > 0 && i % Common.BATCH_SIZE == 0) { //BATCH_SIZE=50
em.flush();
em.clear();
}
Parent myObject = elements.get(i);
session.update(myObject);
}
utx.commit();
当列表小于BATCH_SIZE(<;50)时,编辑是正确的,但是,如果需要刷新和清除语句,我会得到以下错误:
detached entity passed to persist: Child
我也试过:
session.flush();
session.clear();
同样的错误。我有什么遗漏吗
# 1 楼答案
您检查过列表中是否包含重复的对象了吗?如果一个批处理尝试两次更新具有相同标识符的对象,则可能会遇到此问题