我有两个实体，其中一个为
@Entity
public class Job {
@Id
@GeneratedValue
private Integer id;
@Size(min = 5,max = 50, message = "Valid title is 5-50 chars")
private String title;
@ManyToMany(cascade = {CascadeType.MERGE})
@JoinTable(name = "jobs_categories",
joinColumns = @JoinColumn(name = "jobs_id"),
inverseJoinColumns = @JoinColumn(name = "categories_id"))
private List<Category> categories;
// omitting setters/getters
}
其他为
@Entity
public class Category {
@Id
@GeneratedValue
private Integer id;
@Size(min = 5,max = 15, message = "Valid name is 5-15 chars")
private String name;
@ManyToMany(mappedBy = "categories", cascade = {CascadeType.MERGE})
private List<Job> jobs;
// omitting setters/getters
}
我想对这两个实现CRUD操作， 我将一份包含某些类别的工作保存为
Job title - Fullstack JavaScript CSS3 / HTML5 / Developer
Categories - AngularJS, Backbone.js, CSS, CSS3, Graphic design, HTML, HTML5,
JavaScript, MongoDB Node.js, twitter bootstrap, Web design.
然后，如果我想通过从上面保存的作业中添加或删除类别来更新作业，则它永远不会更新(例如，添加/删除)类别。
为了更新作业，我在 JobService 中有方法
@Service
public class JobService{
@Autowired
private JobRepository jobRepository;
@Autowired
private CategoryRepository categoryRepository;
@Autowired
private LocalContainerEntityManagerFactoryBean entityManagerFactory;
private Session session;
Logger logger = LoggerFactory.getLogger(JobService.class);
public void updateJobCategory(Job job) {
EntityManager entityManager = entityManagerFactory.getObject().createEntityManager();
session= entityManager.unwrap(org.hibernate.Session.class);
logger.info("got Job ID as ==> " + String.valueOf(job.getId()));
Job jobObj = (Job) session.get(Job.class, job.getId());
jobObj.getCategories().clear();
logger.info("got Job ID as ==> " + String.valueOf(jobObj.getId()));
if (!job.getCategories().isEmpty()) {
logger.info("got job.getCategories() as not Null");
List<Category> categories = job.getCategories();
for (Category category : categories) {
logger.info("Good job.getCategories() to update ==> " + category.getName());
}
logger.info("adding job.getCategories() to update ==> ");
jobObj.setCategories(job.getCategories());
}else {
logger.info("got job.getCategories() as Null");
}
session.update(jobObj);
}
public void update(Job job) {
jobRepository.update(job.getId(), job.getTitle());
updateJobCategory(job);
}
}
我得到日志
logger.info("Got job.getCategories() to update" + category.getName());
我正在更新(新添加/旧删除)所有类别的列表，
Hibernate: update job set title=? where id=?
INFO : com.rhcloud.jobsnetwork.service.JobService - got Job ID as ==> 1
Hibernate: select job0_.id as id1_1_0_, job0_.title as title7_1_0_ from job job0_ where job0_.id=?
Hibernate: select categories0_.jobs_id as jobs_id1_1_0_, categories0_.categories_id as categori2_2_0_, category1_.id as id1_0_1_, category1_.name as name2_0_1_ from jobs_categories categories0_ inner join category category1_ on categories0_.categories_id=category1_.id where categories0_.jobs_id=?
INFO : com.rhcloud.jobsnetwork.service.JobService - got Job ID as ==> 1
INFO : com.rhcloud.jobsnetwork.service.JobService - got job.getCategories() as not Null
INFO : com.rhcloud.jobsnetwork.service.JobService - Good job.getCategories() to update ==> iOS App Dev
INFO : com.rhcloud.jobsnetwork.service.JobService - Good job.getCategories() to update ==> Android App Dev
INFO : com.rhcloud.jobsnetwork.service.JobService - adding job.getCategories() to update
但是当我看到作业的详细信息时，我得到了列出的类别，这些类别是在创建作业时添加的而不是更新的作业，我猜它没有更新连接表 jobs_categories 中的类别 id 值。
不知道更新与工作相关的类别？
更新
当我使用时
public void persistJob(Job newJob) {
em.persist(newJob);
}
public void saveJob(Job job) {
em.merge(job);
}
public void persistCategory(Category newcat) {
em.persist(newcat);
}
在每个方法中没有@Transactional，我都会得到异常
javax.persistence.TransactionRequiredException: No transactional EntityManager available
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:275)
at com.sun.proxy.$Proxy167.persist(Unknown Source)
at com.rhcloud.jobsnetwork.service.JobService.persistJob(JobService.java:29)
at com.rhcloud.jobsnetwork.service.JobService$$FastClassBySpringCGLIB$$53974ce3.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:649)
at com.rhcloud.jobsnetwork.service.JobService$$EnhancerBySpringCGLIB$$c08e8d16.persistJob(<generated>)
at com.rhcloud.jobsnetwork.controllers.JobController.addJobDetail(JobController.java:86)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:776)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
添加@Transactional后，它可以摆脱上述异常，我使用保存新作业
@RequestMapping(value = "/add-job", method = RequestMethod.POST)
public String addJobDetail(@ModelAttribute("job") Job job) {
jobService.persistJob(job);
return "redirect:/";
}
我让所有事情都完美运行，但是当我在 JobController 中使用 saveJob 时
@RequestMapping(value = "/updated", method = RequestMethod.POST)
public String updateJob(@ModelAttribute("job") Job job) {
jobService.saveJob(job);
return "redirect:/";
}
更新的作业中没有保存任何类别(没有先前添加的没有更新的类别)，在这种情况下有任何建议。
更新 - 2
根据您的建议，我将记录器添加到
@Transactional
public void saveJob(Job job) {
logger.error("got job.getCategories() of " + job.getCategories().size());
em.merge(job);
}
此时我在
处得到 NullPointerException logger.error("got job.getCategories() of " + job.getCategories().size() + " size");
日志/跟踪是
java.lang.NullPointerException
at com.rhcloud.jobsnetwork.service.JobService.saveJob(JobService.java:37)
at com.rhcloud.jobsnetwork.service.JobService$$FastClassBySpringCGLIB$$53974ce3.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at com.rhcloud.jobsnetwork.service.JobService$$EnhancerBySpringCGLIB$$41dc2ac2.saveJob(<generated>)
at com.rhcloud.jobsnetwork.controllers.JobController.updateJob(JobController.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:776)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
最佳答案
就您而言，您有两个实体，每个实体都可以独立存在 - 没有工作的类别也可以，并且工作可以不分配任何类别。 orphanRemoval 用于 OnetoMany 或 OneToOne，如果您想对不再从父实体引用的相关实体(想想组合)执行删除操作，但这里的情况并非如此。我相信您只是想删除工作与特定类别(认为关联)之间的链接。
您的映射是正确的(以 Job 作为关系所有者的双向多对多关系)，我建议仅进行少量修改:
使用java.util.Set(通过在连接表上删除来提高性能，防止“无法获取多个包”异常)进行集合并重写equals方法(使集合操作更容易)。
我们开始:
@Entity
public class Job {
@Id
@GeneratedValue
private Integer id;
private String title;
@ManyToMany(fetch=FetchType.EAGER,cascade = { CascadeType.MERGE })
@JoinTable(name = "jobs_categories", joinColumns = @JoinColumn(name = "jobs_id") , inverseJoinColumns = @JoinColumn(name = "categories_id") )
private Set<Category> categories = new HashSet<Category>();
和类别
@Entity
public class Category {
@Id
@GeneratedValue
private Integer id;
private String name;
@ManyToMany(mappedBy = "categories", cascade = { CascadeType.MERGE })
private List<Job> jobs;
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Category other = (Category) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
更新函数中的问题之一是您覆盖了对作业实体中集合的引用。
jobObj.setCategories(job.getCategories());
您应该始终修改原始集合，切勿分配新集合。
您还可以考虑从 ManyToMany 中完全删除 Merge 级联，因为这将使代码工作流程更容易理解 - 类别将单独管理，并且您只需将已保存的类别添加到新的 Job 实例(但这只是一个建议，我们将使其即使在级联中也能工作:) )。
现在来一些测试代码。我使用普通的 JPA，而不是 Spring 存储库，以使其易于理解。
JobService(在您的情况下，它将分为多个类、存储库..):
public class JobService {
@PersistenceContext
EntityManager em;
public void persistJob(Job newJob) {
em.persist(newJob);
}
public Job getJob(Integer jobId) {
return em.find(Job.class, jobId);
}
public void saveJob(Job job) {
em.merge(job);
}
public void persistCategory(Category newcat) {
em.persist(newcat);
}
public List<Category> getAllCategories() {
return em.createQuery("from Category", Category.class).getResultList();
}
}
让我们测试一下:
Job job = new Job();
job.setTitle("Web developer");
Category catJS = new Category();
catJS.setName("javascript");
Category catCSS = new Category();
catCSS.setName("CSS");
Category catNG = new Category();
catNG.setName("AngualrJS");
Category catHTML = new Category();
catHTML.setName("HTML5");
//persist categories separately
jobservice.persistCategory(catNG);
jobservice.persistCategory(catCSS);
jobservice.persistCategory(catHTML);
jobservice.persistCategory(catJS);
//at this point, we have 4 categories as managed entities
//add the saved categories to a new job instance
job.getCategories().add(catHTML);
job.getCategories().add(catJS);
//save job in DB
jobservice.persistJob(job);
//we do not need to set Job references in Category objects, because Job is the relationship owner - it will correctly update the FKs in join table
assertNotNull("job should be saved", job.getId());
Job fromDb = jobservice.getJob(job.getId());//reload from DB
assertNotNull("job should be stored in DB", fromDb);
assertTrue("job should have 2 categories", fromDb.getCategories().size() == 2);
//great si far so good
//remove one of the assigned categories from Job(this is where you need that **equals** method in Category )
fromDb.getCategories().remove(catHTML);
assertTrue("job should not have only one category in Memory", fromDb.getCategories().size() ==1);
jobservice.saveJob(fromDb);
//we do not want to delete the *HTML* category from DB, just remove it from the particular job
Job fromDbAfterUpdate = jobservice.getJob(job.getId());
assertTrue("job should not have only one category in BD", fromDbAfterUpdate.getCategories().size() ==1);
List<Category> allCategories = jobservice.getAllCategories();
assertTrue("there should still be 4 categories in DB", allCategories.size() == 4);
//now lets test the Merge cascade
Category unsavedCategory = new Category();
unsavedCategory.setName("jquery");
fromDbAfterUpdate.getCategories().add(unsavedCategory );
//we have added an unsaved category to an existing job. As Job has cascade merge on it categories, the *unsavedCategory* will be saved and then linked to job via job_category join table
jobservice.saveJob(fromDbAfterUpdate);
fromDbAfterUpdate = jobservice.getJob(fromDbAfterUpdate.getId());
assertTrue("job should now have 2 categories", fromDbAfterUpdate.getCategories().size() ==2);
// one more test, add and remove at the same time
fromDbAfterUpdate.getCategories().remove(catJS);
fromDbAfterUpdate.getCategories().add(catHTML);
fromDbAfterUpdate.getCategories().add(catCSS);
jobservice.saveJob(fromDbAfterUpdate);
fromDbAfterUpdate = jobservice.getJob(fromDbAfterUpdate.getId());
assertTrue("job should now have 3 categories", fromDbAfterUpdate.getCategories().size() ==3);
allCategories = jobservice.getAllCategories();
assertTrue("there should be 5 categories in DB", allCategories.size() == 5);
TL;博士
- 保持更新方法简单 - 您不需要从数据库获取对象并在托管对象和分离对象之间移动内容，让 JPA 合并完成它的工作
- 切勿更改对托管实体集合的引用 - 直接在集合上执行操作
- 省略任何级联，直到您真正需要为止
更多信息请咨询JPA Spec
关于java - 更新连接表中的值很麻烦 spring data JPA，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33127840/