ManyToMany problem

[swenu]

Hi all

playing around with Seam and trying to fill a manytomany join table. Following situation: A person has multiple roles (based on work, not as a role known from the security). A role could have 0..n functions (specialised education). so i tried the follwing:

Role and Funtion joined on role_function (join table, for the moment only role_id and function_id, in future with a generated id) The qualification table contains person_id and role_function_id.

Now the questions:

1) How to autogenerate an role_function_id on assigning a function to a role?
2) Do i have to develop a seperate bean for the qualification?

Sorry if the question is clear for all. Searched for the answer and didn't find something which will helps out a newbie like me! Hope someone will clear my questions. Thanks in advance.

[wolfgangknauf]

Hi,

I assume that you want to use EJB3/JPA for creating your entities?

In this case, you don't need a role_function entity, and the server will autogenerate the database table for you. The entity "Role" will have a list of "Functions", and the "Function" will have a list of "Role", both connected by annotations.

Pseudocode:

@Entity
public class Role implements Serializable
{
 @ManyToMany (mappedBy="roles")
 public List<Function> functions;
}

@Entity
public class Function implements Serializable
{
 @ManyToMany ()
 public List<Role> roles;
}

Then, your code can access the functions of a role by "myRole.functions.get(x);". The rest is the job of the server and you don't have to care much about it.

Of course, there is quite a bit more to keep in mind. First of all, the two fields should have a getter and setter. More detailed information can be found here: http://www.jboss.org/community/wiki/EJB3relationships

Hope this helps

Wolfgang

[swenu]

Hi Wolfgang

Thanks for your input.
So far i got it already. The role_function is generated automaticly

But now i got
role_id | function_id

What should i do if like a generated id within this table?

Thanks a lot

[wolfgangknauf]

Hi,

basically, you don't need a generated ID for the mapping table because the pair "role_id/function_id" is already a valid primary key.
If you need a id column anyway, you have to build a mapping entity with a generated ID property and two @OneToMany relationship fields to Role and Function.

So your code for mapping a function to a role could be:

RoleToFunction role2FunctionNew = new RoleToFunction();
role2FunctionNew.setFunction(...);
role2FunctionNew.setRole(...);

role.getFunctionmappings().add (role2FunctionNew);

Hope this helps

Wolfgang

[swenu]

Hi Wolfgang

Thanks for your input.
I need the generated id to reference to this pair (role - function).

I tried to do it as it is described here:
http://en.wikibooks.org/wiki/Java_Persistence/ManyToMany#Additional_columns_in_join_table.

for the moment it doesn't work. I'll keep going on this way.
Perhaps i will return a few hours later again with more questions.

[swenu]

Sorry :)

I just stuck here and have no idea what the problem is.

Hope someone got input for me!

Here my classes:

package ch.emtm.entity;

import java.io.Serializable;
import java.util.List;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.Version;

import org.hibernate.validator.Length;
import org.hibernate.validator.NotNull;
import org.jboss.seam.annotations.Name;

@Entity
@Name("role")
public class Role implements Serializable
{
 /**
 *
 */
 private static final long serialVersionUID = 1L;

 @Id
 @GeneratedValue
 private Long id;
 @Version
 private Integer version;
 @Length(max=64)
 @NotNull
 private String name;
 @OneToMany(mappedBy="role")
 private List<RoleFunction> functions;
 @NotNull
 @OneToOne
 @JoinColumn(name = "status")
 private RecordStatus recordStatus = new RecordStatus();

 /**
 * @return the id
 */
 public Long getId() {
 return id;
 }
 /**
 * @param id the id to set
 */
 public void setId(Long id) {
 this.id = id;
 }
 /**
 * @return the version
 */
 public Integer getVersion() {
 return version;
 }
 /**
 * @param version the version to set
 */
 public void setVersion(Integer version) {
 this.version = version;
 }
 /**
 * @return the name
 */
 public String getName() {
 return name;
 }
 /**
 * @param name the name to set
 */
 public void setName(String name) {
 this.name = name;
 }
 /**
 * @return the functions
 */
 public List<RoleFunction> getFunctions() {
 return functions;
 }
 /**
 * @param functions the functions to set
 */
 public void setFunctions(List<RoleFunction> functions) {
 this.functions = functions;
 }
 /**
 * @return the recordStatus
 */
 public RecordStatus getRecordStatus() {
 return recordStatus;
 }
 /**
 * @param recordStatus the recordStatus to set
 */
 public void setRecordStatus(RecordStatus recordStatus) {
 this.recordStatus = recordStatus;
 }

}

package ch.emtm.entity;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.Version;

import org.hibernate.validator.Length;
import org.hibernate.validator.NotNull;
import org.jboss.seam.annotations.Name;

@Entity
@Name("function")
public class Function implements Serializable
{
 /**
 *
 */
 private static final long serialVersionUID = 1L;

 @Id
 @GeneratedValue
 private Long id;
 @Version
 private Integer version;
 @Length(max = 64)
 @NotNull
 private String name;
 @OneToMany(mappedBy="function")
 private List<RoleFunction> roles = new ArrayList<RoleFunction>();
 @NotNull
 @OneToOne
 @JoinColumn(name = "status")
 private RecordStatus recordStatus = new RecordStatus();

 public Long getId() {
 return id;
 }

 public void setId(Long id) {
 this.id = id;
 }

 public Integer getVersion() {
 return version;
 }

 @SuppressWarnings("unused")
 private void setVersion(Integer version) {
 this.version = version;
 }

 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }

 /**
 * @return the roles
 */
 public List<RoleFunction> getRoles() {
 return roles;
 }

 /**
 * @param roles the roles to set
 */
 public void setRoles(List<RoleFunction> roles) {
 this.roles = roles;
 }

 /**
 * @return the recordStatus
 */
 public RecordStatus getRecordStatus() {
 return recordStatus;
 }

 /**
 * @param recordStatus the recordStatus to set
 */
 public void setRecordStatus(RecordStatus recordStatus) {
 this.recordStatus = recordStatus;
 }

}

package ch.emtm.entity;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.PrimaryKeyJoinColumn;

import org.jboss.seam.annotations.Name;

@Entity
@Name("rolefunction")
public class RoleFunction implements Serializable
{
 /**
 *
 */
 private static final long serialVersionUID = 1L;

 @Id
 @GeneratedValue
 private Long id;
 @ManyToOne()
 @PrimaryKeyJoinColumn(name = "function", referencedColumnName = "id")
 private Function function = new Function();
 @ManyToOne()
 @PrimaryKeyJoinColumn(name = "role", referencedColumnName = "id")
 private Role role = new Role();
// @OneToMany(mappedBy="roleFunction")
// private List<Qualification> qualifications = new ArrayList<Qualification>();

 /**
 * @return the id
 */
 public Long getId() {
 return id;
 }
 /**
 * @param id the id to set
 */
 public void setId(Long id) {
 this.id = id;
 }
 /**
 * @return the roleId
 */
 public Role getRole() {
 return role;
 }
 /**
 * @param roleId the roleId to set
 */
 public void setRole(Role role) {
 this.role = role;
 }
 /**
 * @return the functionId
 */
 public Function getFunction() {
 return function;
 }
 /**
 * @param functionId the functionId to set
 */
 public void setFunction(Function function) {
 this.function = function;
 }
// /**
// * @return the qualifications
// */
// public List<Qualification> getQualifications() {
// return qualifications;
// }
// /**
// * @param qualifications the qualifications to set
// */
// public void setQualifications(List<Qualification> qualifications) {
// this.qualifications = qualifications;
// }

}

So i get an error:

21:20:01,733 SEVERE [application] java.lang.NullPointerException
javax.faces.el.EvaluationException: java.lang.NullPointerException
 at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
 at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
 at javax.faces.component.UICommand.broadcast(UICommand.java:387)
 at org.ajax4jsf.component.AjaxViewRoot.processEvents(AjaxViewRoot.java:321)
 at org.ajax4jsf.component.AjaxViewRoot.broadcastEvents(AjaxViewRoot.java:296)
 at org.ajax4jsf.component.AjaxViewRoot.processPhase(AjaxViewRoot.java:253)
 at org.ajax4jsf.component.AjaxViewRoot.processApplication(AjaxViewRoot.java:466)
 at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
 at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
 at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
 at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:510)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
 at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178)
 at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
 at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:368)
 at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:495)
 at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.HotDeployFilter.doFilter(HotDeployFilter.java:53)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
 at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
 at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
 at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
 at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
 at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:598)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
 at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
 at ch.emtm.session.RoleHome.update(RoleHome.java:62)

[swenu]

one step closer :D

i got the problem - at least i think i'm close to!
on roleList.xhtml i got:

<s:decorate id="functionField" template="layout/edit.xhtml">
<ui:define name="label">Function</ui:define> <h:selectManyCheckbox id="functions" value="#{roleHome.instance.functions}" layout="pageDirection">
<s:selectItems value="#{functionList.resultList}" var="function" label="#{function.name}" />
<s:convertEntity />
</h:selectManyCheckbox>
</s:decorate>

and when i save i receive the following error:

23:33:05,776 SEVERE [application] java.lang.ClassCastException: ch.emtm.entity.Function cannot be cast to ch.emtm.entity.RoleFunction

i understood the problem, but for the moment i have no idea how to solve.
i think your code posted above with the new rolefunction() will solve - but i couldn't get.

Do you have a hint for me ;)

Thanks in advance

[swenu]

Hi again :D

i found a solution - at least i'm close to a solution.

I added this function to the Role.

@OneToMany(mappedBy="role")
private List<RoleFunction> listRoleFunctions;
...
public List<Function> getFunctions(){
 List<Function> functions = new ArrayList<Function>();
 if(this.listRoleFunctions != null){
 for(RoleFunction rf:this.listRoleFunctions){
 Function f = new Function();
 f = rf.getFunction();
 functions.add(f);
 }
 }
 return functions;
 }

 public void setFunctions(List<Function> functions){
 if(functions.size() > this.listRoleFunctions.size()){
 //New function to add
 for(Function f:functions){
 boolean add = true;
 for(RoleFunction roleFunction:this.listRoleFunctions){
 if(roleFunction.getId().equals(f.getId())){
 add = false;
 break;
 }

 }
 if(add){
 RoleFunction rf = new RoleFunction();
 rf.setFunction(f);
 rf.setRole(this);
 System.out.println("Adding (rf from lRF)"+rf.getRole().getName() +"."+rf.getFunction().getName());
 this.listRoleFunctions.add(rf);
 }
 }
 }else{
 //Function to remove
 System.out.println("remove function");
 for(RoleFunction roleFunction:this.listRoleFunctions){
 boolean remove = true;
 for(Function f:functions){
 if(roleFunction.getId().equals(f.getId())){
 remove = false;
 break;
 }
 }
 if(remove){
 this.listRoleFunctions.remove(roleFunction);
 }
 }
 }
 }

The only thing which doesn't work is if a user deselect a already saved function assignment.

I always get this error:

10:49:58,960 INFO [STDOUT] remove function
10:49:58,960 SEVERE [component] /roleList.xhtml @72,106 value="#{roleHome.instance.functions}": Error writing 'functions' on type ch.emtm.entity.Role
java.util.ConcurrentModificationException
 at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
 at java.util.AbstractList$Itr.next(AbstractList.java:343)
 at org.hibernate.collection.AbstractPersistentCollection$IteratorProxy.next(AbstractPersistentCollection.java:577)
...

Hope someone got input to solve this issue!
Thanks in advance for any hint

Greets

[wolfgangknauf]

Hi,

that's a standard iterator problem, no EJB3 issue ;-):

for(RoleFunction roleFunction:this.listRoleFunctions){
 ...
 this.listRoleFunctions.remove(roleFunction);

You remove an item from the list over which you iterate. Use this "for (int index = this.listRoleFunctions.size() - 1; index >= 0; index--)" to avoid this.

Best regards

Wolfgang

[swenu]

Booah thanks for the fast answer :D

New to all the things here - i'm so sorry!

Next question i got!
After i remover the roleFunction from the listRoleFunctions (i've checked, it's okay) and save the removed item is still available in the database!
Bad news: there's no stack trace neither in console nor server.log!

Hope this issue is as simple to solve as the last one =)

Thanks for your assistance!

Best regards, Sven

[wolfgangknauf]

Hi Sven (from Germany?),

another fast answer, but it will give you a bit to read and think about: http://www.jboss.org/community/wiki/EJB3relationships
I hope the section "Managing the (bidirectional) relationship" will provide you with explanations on how to fix this.

Wolfgang

[wolfgangknauf]

I see that I posted this link already earlier in this thread. Sorry for this duplicate ;-)!

Wolfgang

[swenu]

Hi Wolfgang

close to Germany from [ + ] ;)

thanks i will have a look at it again - hope to get it work now.
Will return if i get questions or if it's done.

[swenu]

Sorry back again *grml*

I don't get it - cause i'm doing the assignment in the entity not in the bean. Imho there's a difference to the text you've wrote.

I tried to remove the refernces within the remove loop from both sides. No effect =(

[wolfgangknauf]

Hi,

could you post the updated code which removes from the relationship, and also the relationship related snippets of the entities? There were so many changes that I need a full update of it ;-).

I think it is better to keep this code in the session bean, because you are manipulating more than one entity with it.

Best regards

Wolfgang