[英]Hibernate: Using collection of complex objects throws exceptions
我正在研究Hibernate,並存儲復雜類型的集合。 但是我遇到了例外。
我有以下持久性課程:
public class Item {
private Long id;
private Set images = new HashSet();
private Collection<Data> data = new ArrayList<Data>();
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Set getImages() {
return images;
}
public void setImages(Set images) {
this.images = images;
}
public Collection<Data> getData() {
return data;
}
public void setData(Collection<Data> data) {
this.data = data;
}
}
數據類如下:
public class Data {
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Override
public boolean equals(Object obj) {
if(!(obj instanceof Data) )
return false;
Data d = (Data) obj;
if(d.firstName.equals(firstName) && d.lastName.equals(lastName))
return true;
return false;
}
@Override
public int hashCode() {
int result;
result = 17;
result = 31 * result + firstName.hashCode();
result = 31 * result + lastName.hashCode();
return result;
}
映射文件如下:
對於商品類:
<hibernate-mapping>
<class name="com.entities.Item" table="ITEM">
<id name="id" type="java.lang.Long">
<column name="ID" />
<generator class="identity" />
</id>
<set name="images" table="ITEM_IMAGE" inverse="false" lazy="true">
<key>
<column name="ID" />
</key>
<element type="string">
<column name="IMAGES" />
</element>
</set>
<bag name="data" table="DATA" inverse="false" lazy="true">
<key>
<column name="ID" />
</key>
<one-to-many class="com.entities.Data" />
</bag>
</class>
</hibernate-mapping>
對於數據類:
<hibernate-mapping>
<class name="com.entities.Data" table="DATA">
<id name="firstName" type="java.lang.String">
<column name="FIRSTNAME" />
<generator class="assigned" />
</id>
<property name="lastName" type="java.lang.String">
<column name="LASTNAME" />
</property>
</class>
</hibernate-mapping>
在我的將數據保存到MySQL的代碼中:
Transaction tx = session.beginTransaction();
Item item = new Item();
Set images = new HashSet();
images.add("C:\\");
images.add("D:\\");
item.setImages(images);
List<Data> data = new ArrayList<Data>();
Data a = new Data();
a.setFirstName("John");
a.setLastName("Smith");
data.add(a);
item.setData(data);
session.save(item);
tx.commit();//-->Exception here
session.close();
我在tx.commit();
上收到以下異常tx.commit();
休眠:插入ITEM值()休眠:插入ITEM_IMAGE(ID,IMAGES)值(?,?)休眠:插入ITEM_IMAGE(ID,IMAGES)值(?,?)休眠:更新數據集ID =? 其中FIRSTNAME =? 休眠:更新數據集ID =? 其中FIRSTNAME =? 1454 [main]錯誤org.hibernate.jdbc.AbstractBatcher-執行批處理的異常:org.hibernate.StaleStateException:批處理更新從更新[0]返回意外行數; 實際行數:0; 預期值:org.hibernate.jdbc.BatchingBatcher的org.hibernate.jdbc.Expectations $ BasicExpectation $ BasicExpectation.verifyOutcome(Expectations.java:70)的org.hibernate.jdbc.Expectations $ BasicExpectation.checkBatched(Expectations.java:85)處為1。在org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)在org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)處的checkRowCounts(BatchingBatcher.java:90)在org.hibernate.engine.ActionQueue處org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:188)在org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)處的.executeActions(ActionQueue.java:268)。在org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)在org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:383)處的event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51) .hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:133)位於com.entiti es.Main.main(Main.java:44)
為什么會出現此異常?
如果我刪除Collection<Data> data
以僅存儲Set
該代碼有效,並且數據保存在MySQL中。
注意:映射文件是由Eclipse Hibernate插件創建的。
對您的代碼進行了以下更改:
Transaction tx = session.beginTransaction();
Item item = new Item();
//added save here to attach the object to persistance context.
// (This might be optional)
session.save(item);
Set images = new HashSet();
images.add("C:\\");
images.add("D:\\");
item.setImages(images);
List<Data> data = new ArrayList<Data>();
Data a = new Data();
a.setFirstName("John");
a.setLastName("Smith");
//added save here to attach the object to persistance context.
//this is required without cascading settings
session.save(a)
data.add(a);
item.setData(data);
session.save(item);
tx.commit();//-->Exception here
session.close();
否則,您可以在袋子上設置適當的層疊選項!
AFAIK,您收到此錯誤,是因為您嘗試在沒有其他實體(數據)處於持久狀態的情況下保持關聯並且默認情況下將級聯選項設置為none。 再次,我沒有嘗試運行我的片段,但這將為您指明正確的方向。
從OP更新:
通過使用inverse="true"
進行cascade
解決了問題,而且我還必須從Data
引用到Item
否則FK列不會更新
可能是由於您向列表data
添加a
兩次的事實?
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