通过未标记为 cascade PERSIST 的关系找到了一个新对象 [英] a new object was found through a relationship that was not marked cascade PERSIST
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问题描述
在尝试获得 Article 和 HeaderField 之间的 @OneToMany 关系时，我的映射可能不太正确，导致:
In trying to get a @OneToMany relationship between Article and HeaderField I probably have the mapping not quite right, resulting in:
init:
Deleting: /home/thufir/NetBeansProjects/USENET/build/built-jar.properties
deps-jar:
Updating property file: /home/thufir/NetBeansProjects/USENET/build/built-jar.properties
compile:
run:
DEBUG: nntp: newsrc loading /home/thufir/.newsrc
DEBUG: nntp: newsrc load: 1 groups in 31ms
[EL Info]: 2012-07-31 02:05:05.677--ServerSession(8979162)--EclipseLink, version: Eclipse Persistence Services - 2.3.0.v20110604-r9504
[EL Info]: 2012-07-31 02:05:06.778--ServerSession(8979162)--file:/home/thufir/NetBeansProjects/USENET/build/classes/_USENETPU login successful
[EL Warning]: 2012-07-31 02:05:06.903--ServerSession(8979162)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'usenet.HEADERFIELD' doesn't exist
Error Code: 1146
Call: ALTER TABLE HEADERFIELD DROP FOREIGN KEY FK_HEADERFIELD_ARTICLE_ID
Query: DataModifyQuery(sql="ALTER TABLE HEADERFIELD DROP FOREIGN KEY FK_HEADERFIELD_ARTICLE_ID")
[EL Warning]: 2012-07-31 02:05:06.916--ServerSession(8979162)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown table 'ARTICLE'
Error Code: 1051
Call: DROP TABLE ARTICLE
Query: DataModifyQuery(sql="DROP TABLE ARTICLE")
[EL Warning]: 2012-07-31 02:05:07.033--ServerSession(8979162)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown table 'NEWSGROUP'
Error Code: 1051
Call: DROP TABLE NEWSGROUP
Query: DataModifyQuery(sql="DROP TABLE NEWSGROUP")
[EL Warning]: 2012-07-31 02:05:07.122--ServerSession(8979162)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown table 'HEADERFIELD'
Error Code: 1051
Call: DROP TABLE HEADERFIELD
Query: DataModifyQuery(sql="DROP TABLE HEADERFIELD")
[EL Warning]: 2012-07-31 02:05:08.921--UnitOfWork(26970615)--java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: null.
Jul 31, 2012 2:05:08 AM net.bounceme.dur.usenet.driver.Main main
SEVERE: null
javax.persistence.RollbackException: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: null.
at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commitInternal(EntityTransactionImpl.java:102)
at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:63)
at net.bounceme.dur.usenet.driver.Main.persistArticle(Main.java:67)
at net.bounceme.dur.usenet.driver.Main.<init>(Main.java:43)
at net.bounceme.dur.usenet.driver.Main.main(Main.java:24)
Caused by: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: null.
at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.discoverUnregisteredNewObjects(RepeatableWriteUnitOfWork.java:302)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.calculateChanges(UnitOfWorkImpl.java:695)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitToDatabaseWithChangeSet(UnitOfWorkImpl.java:1482)
at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.commitRootUnitOfWork(RepeatableWriteUnitOfWork.java:265)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitAndResume(UnitOfWorkImpl.java:1135)
at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commitInternal(EntityTransactionImpl.java:84)
... 4 more
[EL Info]: 2012-07-31 02:05:09.332--ServerSession(8979162)--file:/home/thufir/NetBeansProjects/USENET/build/classes/_USENETPU logout successful
BUILD SUCCESSFUL (total time: 9 seconds)
文章:
package net.bounceme.dur.usenet.model;
import java.io.Serializable;
import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.mail.Header;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.persistence.*;
@Entity
public class Article implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger LOG = Logger.getLogger(Article.class.getName());
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column
private String subject;
@OneToMany(mappedBy = "article", cascade = CascadeType.PERSIST)
private List<HeaderField> headerFields = new ArrayList<>();
public Article() {
}
public Article(Message message) {
try {
subject = message.getSubject();
Enumeration e = message.getAllHeaders();
while (e.hasMoreElements()) {
Header header = (Header) e.nextElement();
@SuppressWarnings("unchecked")
SimpleEntry nameValue = new SimpleEntry(header.getName(), header.getValue());
HeaderField headerField = new HeaderField(nameValue);
headerFields.add(headerField);
}
} catch (MessagingException ex) {
Logger.getLogger(Article.class.getName()).log(Level.SEVERE, null, ex);
}
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Article)) {
return false;
}
Article other = (Article) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
@Override
public String toString() {
return subject;
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
}
标头字段:
package net.bounceme.dur.usenet.model;
import java.io.Serializable;
import java.util.AbstractMap.SimpleEntry;
import java.util.logging.Logger;
import javax.persistence.*;
@Entity
public class HeaderField implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger LOG = Logger.getLogger(HeaderField.class.getName());
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@ManyToOne
private Article article = new Article();
@Column
private String headerName;
@Column
private String headerValue;
public HeaderField() {
}
public HeaderField(SimpleEntry nameValue) {
headerName = nameValue.getKey().toString();
headerValue = nameValue.getValue().toString();
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof HeaderField)) {
return false;
}
HeaderField other = (HeaderField) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
@Override
public String toString() {
return "
headerName " + headerName + "
headerValue " + headerValue;
}
public String getHeaderName() {
return headerName;
}
public void setHeaderName(String headerName) {
this.headerName = headerName;
}
public String getHeaderValue() {
return headerValue;
}
public void setHeaderValue(String headerValue) {
this.headerValue = headerValue;
}
}
实体已更新以反映使用 CascadeType.PERSIST 的建议，这似乎可以修复该特定错误消息.我正在努力生成更有用的日志来跟踪正在发生的事情.
The entities have been updated to reflect suggestion to use CascadeType.PERSIST which, seemingly, would fix that particular error message. I'm working on generating a more useful log to trace what's happening.
推荐答案
您可能已经创建了 Article 的新实例和 HeaderField 的一些新实例.然后将 HeaderField 的这些实例与 Article 相关联.
What you had likely done is that you created new instance of Article and and some new instance(s) of HeaderField. These instance(s) of HeaderField were then associated with Article.
之后尝试持久化文章失败，因为如错误消息所述，它指的是新对象并且关系未标记为 PERSIST.此外，根据您的日志，这些 HeaderField 实例没有设置 headerName 和 headerValue.
After that trying to persist Article fails, because as error message says, it refers to new objects and relationship is not marked as PERSIST. Additionally according your logs these instances of HeaderField does not have headerName and headerValue set.
你有两个选择:
- 通过 em.persist 还保留文章中引用的其他实例
从文章到 HeaderFields 的级联持久化操作
- persist also other instances referenced from Article via em.persist
cascade persist operation from Article to HeaderFields with following
OneToMany(mappedBy = "article", cascade = CascadeType.PERSIST)
private List<HeaderField> someOrAllHeaderFields = new ArrayList<>();
此外，您不应删除无参数构造函数.JPA 实现总是在创建实例时调用此构造函数.
Additionally you should not remove no-arg constructor. JPA implementation always calls this constructor when it creates instance.
但是你可以保护无参数构造函数.在 JPA 2.0 规范中，这是用下面的话来说明的:
But you can make no-arg constructor protected. In JPA 2.0 specification this is told wit following words:
实体类必须有一个无参数的构造函数.实体类可以还有其他构造函数.无参数构造函数必须是公共的或受保护.
The entity class must have a no-arg constructor. The entity class may have other constructors as well. The no-arg constructor must be public or protected.
这篇关于通过未标记为 cascade PERSIST 的关系找到了一个新对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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