JSF Datamodel & JPA parent to leaves navigation. How to? - jsf

Question

My web application is a CRUD web application based on JSF 2.0 / JPA using Java EE 5 and JDK 1.6. Running on Glassfish 3.1. The IDE is Netbeans 7.0. (I do not use EJB, nor CDI).
THE PROBLEM
What I can achieve now is perform CRUD on my entities. Which is fine. For each entity I have:
List.xhtml (LIsting all Datamodel items for that entity in datatable)
Create.xhtml (A form to create a new item)
View.xhtml (a form to view an item)
Edit.xhtml (a form to edit an item)
Structure
entities package: entities.
jpa.controllers package: JPA controllers (Javax persistence..).
jsf package: a managed bean for each entity (session Scoped).
But the main problem is parent-leaf navigation. I want my webapp to do the same thing as the Demo application Agile ScrumToys that comes along shipped with Netbeans 7.0. or the demo webapp from SpringFuse, otherwise :
E.G: When you display a list of WRITERS in a you have the last <h:column> where you put three <h:commandLink /> for editing, viewing and deleting the selected row.
What I intend to do is to add another in the same column that allows me to view a collection of child objects related to that selected row.
Hence, I want to show the list of BOOKS written by a given WRITER.
WRITER 1 ---------- * BOOK (one-to-many) relationship.
When the user clicks on the
<h:commandButton action="#{someManagedBean.showBooksForWriter}" value="#{i18n.listBooks}" /> it forwards him to the /book/List.xhtml (list of the selected WRITEr row should appear). And so on, from the book datatable, from a given row, I click on <h:commandLink action="#{someManagedBean.showReferencesForBook}" value="List of Book References"/> to get the list of references for the given book.
A given hint by #Matt was to use a method in the book managed bean:
public showBooksForWriter(Writer writer) {
// TODO: get the selected writer
// Get the list of books for the selected writer
return "/book/List"; // Outcome
}
And in the view :
<h:datatable value="#{writerController.items}" var="w">
.....
<h:column>
<h:commandButton action="#{bookController.showBooksForWriter(w}" value="Show Books For Writer"/>
</h:column>
....
</h:datatable>
But I could not figure how to (DataModel is driving mad). So if anyone could help! It would be very appreciated!
Below is my code
the WRITER entity:
package entities;
import javax.persistence.*; // other imports
#Entity
#Table(name = "WRITER")
#XmlRootElement
#NamedQueries({
#NamedQuery(name = "Writer.findAll", query = "SELECT w FROM Writer w"),
#NamedQuery(name = "Writer.findByWriterid", query = "SELECT w FROM Writer w WHERE w.writerid = :writerid"),
#NamedQuery(name = "Writer.findByName", query = "SELECT w FROM Writer w WHERE w.name = :name"),
#NamedQuery(name = "Writer.findBySurname", query = "SELECT w FROM Writer w WHERE w.surname = :surname"),
#NamedQuery(name = "Writer.findByMiddlename", query = "SELECT w FROM Writer w WHERE w.middlename = :middlename"),
#NamedQuery(name = "Writer.findByIsRewarded", query = "SELECT w FROM Writer w WHERE w.isRewarded = :isRewarded")})
public class Writer implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#NotNull
#Column(name = "writerid")
private Integer writerid;
#Size(max = 45)
#Column(name = "name")
private String name;
#Size(max = 45)
#Column(name = "surname")
private String surname;
#Size(max = 45)
#Column(name = "middlename")
private String middlename;
#Column(name = "isRewarded")
private Boolean isRewarded;
#ManyToMany(mappedBy = "writerList")
private List<Topic> topicList;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "writer")
private List<Evaluation> evaluationList;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "writer")
private List<Book> bookList;
public Writer() {
}
public Writer(Integer writerid) {
this.writerid = writerid;
}
public Integer getWriterid() {
return writerid;
}
public void setWriterid(Integer writerid) {
this.writerid = writerid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
public String getMiddlename() {
return middlename;
}
public void setMiddlename(String middlename) {
this.middlename = middlename;
}
public Boolean getIsRewarded() {
return isRewarded;
}
public void setIsRewarded(Boolean isRewarded) {
this.isRewarded = isRewarded;
}
#XmlTransient
public List<Topic> getTopicList() {
return topicList;
}
public void setTopicList(List<Topic> topicList) {
this.topicList = topicList;
}
#XmlTransient
public List<Evaluation> getEvaluationList() {
return evaluationList;
}
public void setEvaluationList(List<Evaluation> evaluationList) {
this.evaluationList = evaluationList;
}
#XmlTransient
public List<Book> getBookList() {
return bookList;
}
public void setBookList(List<Book> bookList) {
this.bookList = bookList;
}
#Override
public int hashCode() {
int hash = 0;
hash += (writerid != null ? writerid.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 Writer)) {
return false;
}
Writer other = (Writer) object;
if ((this.writerid == null && other.writerid != null) || (this.writerid != null && !this.writerid.equals(other.writerid))) {
return false;
}
return true;
}
#Override
public String toString() {
return getMiddlename();
}
}
The Writer MANAGED BEAN
package jsf;
import entities.Writer;
import jsf.util.JsfUtil;
import jsf.util.PaginationHelper;
import jpa.controllers.WriterJpaController;
import javax.faces.bean.ManagedBean;
// other imports here
#ManagedBean(name = "writerController")
#SessionScoped
public class WriterController implements Serializable {
#Resource
private UserTransaction utx = null;
#PersistenceUnit(unitName = "writerPU")
private EntityManagerFactory emf = null;
private Writer current;
private DataModel items = null;
private WriterJpaController jpaController = null;
private PaginationHelper pagination;
private int selectedItemIndex;
public WriterController() {
}
public Writer getSelected() {
if (current == null) {
current = new Writer();
selectedItemIndex = -1;
}
return current;
}
private WriterJpaController getJpaController() {
if (jpaController == null) {
jpaController = new WriterJpaController(utx, emf);
}
return jpaController;
}
public PaginationHelper getPagination() {
if (pagination == null) {
pagination = new PaginationHelper(10) {
#Override
public int getItemsCount() {
return getJpaController().getWriterCount();
}
#Override
public DataModel createPageDataModel() {
return new ListDataModel(getJpaController().findWriterEntities(getPageSize(), getPageFirstItem()));
}
};
}
return pagination;
}
public String prepareList() {
recreateModel();
return "List";
}
public String prepareView() {
current = (Writer) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
return "View";
}
public String prepareCreate() {
current = new Writer();
selectedItemIndex = -1;
return "Create";
}
public String create() {
try {
getJpaController().create(current);
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("WriterCreated"));
return prepareCreate();
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
return null;
}
}
public String prepareEdit() {
current = (Writer) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
return "Edit";
}
public String update() {
try {
getJpaController().edit(current);
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("WriterUpdated"));
return "View";
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
return null;
}
}
public String destroy() {
current = (Writer) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
performDestroy();
recreateModel();
return "List";
}
public String destroyAndView() {
performDestroy();
recreateModel();
updateCurrentItem();
if (selectedItemIndex >= 0) {
return "View";
} else {
// all items were removed - go back to list
recreateModel();
return "List";
}
}
private void performDestroy() {
try {
getJpaController().destroy(current.getWriterid());
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("WriterDeleted"));
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
}
}
private void updateCurrentItem() {
int count = getJpaController().getWriterCount();
if (selectedItemIndex >= count) {
// selected index cannot be bigger than number of items:
selectedItemIndex = count - 1;
// go to previous page if last page disappeared:
if (pagination.getPageFirstItem() >= count) {
pagination.previousPage();
}
}
if (selectedItemIndex >= 0) {
current = getJpaController().findWriterEntities(1, selectedItemIndex).get(0);
}
}
public DataModel getItems() {
if (items == null) {
items = getPagination().createPageDataModel();
}
return items;
}
private void recreateModel() {
items = null;
}
public String next() {
getPagination().nextPage();
recreateModel();
return "List";
}
public String previous() {
getPagination().previousPage();
recreateModel();
return "List";
}
public SelectItem[] getItemsAvailableSelectMany() {
return JsfUtil.getSelectItems(getJpaController().findWriterEntities(), false);
}
public SelectItem[] getItemsAvailableSelectOne() {
return JsfUtil.getSelectItems(getJpaController().findWriterEntities(), true);
}
#FacesConverter(forClass = Writer.class)
public static class WriterControllerConverter implements Converter {
public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
if (value == null || value.length() == 0) {
return null;
}
WriterController controller = (WriterController) facesContext.getApplication().getELResolver().
getValue(facesContext.getELContext(), null, "writerController");
return controller.getJpaController().findWriter(getKey(value));
}
java.lang.Integer getKey(String value) {
java.lang.Integer key;
key = Integer.valueOf(value);
return key;
}
String getStringKey(java.lang.Integer value) {
StringBuffer sb = new StringBuffer();
sb.append(value);
return sb.toString();
}
public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
if (object == null) {
return null;
}
if (object instanceof Writer) {
Writer o = (Writer) object;
return getStringKey(o.getWriterid());
} else {
throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + WriterController.class.getName());
}
}
}
}
JSF Utility Class
package jsf.util;
import javax.faces.application.FacesMessage;
// Other imports here
public class JsfUtil {
public static SelectItem[] getSelectItems(List<?> entities, boolean selectOne) {
int size = selectOne ? entities.size() + 1 : entities.size();
SelectItem[] items = new SelectItem[size];
int i = 0;
if (selectOne) {
items[0] = new SelectItem("", "---");
i++;
}
for (Object x : entities) {
items[i++] = new SelectItem(x, x.toString());
}
return items;
}
public static void addErrorMessage(Exception ex, String defaultMsg) {
String msg = ex.getLocalizedMessage();
if (msg != null && msg.length() > 0) {
addErrorMessage(msg);
} else {
addErrorMessage(defaultMsg);
}
}
public static void addErrorMessages(List<String> messages) {
for (String message : messages) {
addErrorMessage(message);
}
}
public static void addErrorMessage(String msg) {
FacesMessage facesMsg = new FacesMessage(FacesMessage.SEVERITY_ERROR, msg, msg);
FacesContext.getCurrentInstance().addMessage(null, facesMsg);
}
public static void addSuccessMessage(String msg) {
FacesMessage facesMsg = new FacesMessage(FacesMessage.SEVERITY_INFO, msg, msg);
FacesContext.getCurrentInstance().addMessage("successInfo", facesMsg);
}
public static String getRequestParameter(String key) {
return FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get(key);
}
public static Object getObjectFromRequestParameter(String requestParameterName, Converter converter, UIComponent component) {
String theId = JsfUtil.getRequestParameter(requestParameterName);
return converter.getAsObject(FacesContext.getCurrentInstance(), component, theId);
}
}
JSF Pagination helper
package jsf.util;
import javax.faces.model.DataModel;
public abstract class PaginationHelper {
private int pageSize;
private int page;
public PaginationHelper(int pageSize) {
this.pageSize = pageSize;
}
public abstract int getItemsCount();
public abstract DataModel createPageDataModel();
public int getPageFirstItem() {
return page * pageSize;
}
public int getPageLastItem() {
int i = getPageFirstItem() + pageSize - 1;
int count = getItemsCount() - 1;
if (i > count) {
i = count;
}
if (i < 0) {
i = 0;
}
return i;
}
public boolean isHasNextPage() {
return (page + 1) * pageSize + 1 <= getItemsCount();
}
public void nextPage() {
if (isHasNextPage()) {
page++;
}
}
public boolean isHasPreviousPage() {
return page > 0;
}
public void previousPage() {
if (isHasPreviousPage()) {
page--;
}
}
public int getPageSize() {
return pageSize;
}
} // END of CLASS
The JPA Controller
package jpa.controllers;
import entities.Writer;
// other imports here
public class WriterJpaController implements Serializable {
public WriterJpaController(UserTransaction utx, EntityManagerFactory emf) {
this.utx = utx;
this.emf = emf;
}
private UserTransaction utx = null;
private EntityManagerFactory emf = null;
public EntityManager getEntityManager() {
return emf.createEntityManager();
}
public void create(Writer writer) throws RollbackFailureException, Exception {
if (writer.getTopicList() == null) {
writer.setTopicList(new ArrayList<Topic>());
}
if (writer.getEvaluationList() == null) {
writer.setEvaluationList(new ArrayList<Evaluation>());
}
if (writer.getBookList() == null) {
writer.setBookList(new ArrayList<Book>());
}
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
List<Topic> attachedTopicList = new ArrayList<Topic>();
for (Topic topicListTopicToAttach : writer.getTopicList()) {
topicListTopicToAttach = em.getReference(topicListTopicToAttach.getClass(), topicListTopicToAttach.getTopicname());
attachedTopicList.add(topicListTopicToAttach);
}
writer.setTopicList(attachedTopicList);
List<Evaluation> attachedEvaluationList = new ArrayList<Evaluation>();
for (Evaluation evaluationListEvaluationToAttach : writer.getEvaluationList()) {
evaluationListEvaluationToAttach = em.getReference(evaluationListEvaluationToAttach.getClass(), evaluationListEvaluationToAttach.getEvaluationPK());
attachedEvaluationList.add(evaluationListEvaluationToAttach);
}
writer.setEvaluationList(attachedEvaluationList);
List<Book> attachedBookList = new ArrayList<Book>();
for (Book bookListBookToAttach : writer.getBookList()) {
bookListBookToAttach = em.getReference(bookListBookToAttach.getClass(), bookListBookToAttach.getBookPK());
attachedBookList.add(bookListBookToAttach);
}
writer.setBookList(attachedBookList);
em.persist(writer);
for (Topic topicListTopic : writer.getTopicList()) {
topicListTopic.getWriterList().add(writer);
topicListTopic = em.merge(topicListTopic);
}
for (Evaluation evaluationListEvaluation : writer.getEvaluationList()) {
Writer oldWriterOfEvaluationListEvaluation = evaluationListEvaluation.getWriter();
evaluationListEvaluation.setWriter(writer);
evaluationListEvaluation = em.merge(evaluationListEvaluation);
if (oldWriterOfEvaluationListEvaluation != null) {
oldWriterOfEvaluationListEvaluation.getEvaluationList().remove(evaluationListEvaluation);
oldWriterOfEvaluationListEvaluation = em.merge(oldWriterOfEvaluationListEvaluation);
}
}
for (Book bookListBook : writer.getBookList()) {
Writer oldWriterOfBookListBook = bookListBook.getWriter();
bookListBook.setWriter(writer);
bookListBook = em.merge(bookListBook);
if (oldWriterOfBookListBook != null) {
oldWriterOfBookListBook.getBookList().remove(bookListBook);
oldWriterOfBookListBook = em.merge(oldWriterOfBookListBook);
}
}
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public void edit(Writer writer) throws IllegalOrphanException, NonexistentEntityException, RollbackFailureException, Exception {
// remainder of code goes here
}
public void destroy(Integer id) throws IllegalOrphanException, NonexistentEntityException, RollbackFailureException, Exception {
// remainder of code goes here
}
public List<Writer> findWriterEntities() {
return findWriterEntities(true, -1, -1);
}
public List<Writer> findWriterEntities(int maxResults, int firstResult) {
return findWriterEntities(false, maxResults, firstResult);
}
private List<Writer> findWriterEntities(boolean all, int maxResults, int firstResult) {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
cq.select(cq.from(Writer.class));
Query q = em.createQuery(cq);
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
} finally {
em.close();
}
}
public Writer findWriter(Integer id) {
EntityManager em = getEntityManager();
try {
return em.find(Writer.class, id);
} finally {
em.close();
}
}
public int getWriterCount() {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
Root<Writer> rt = cq.from(Writer.class);
cq.select(em.getCriteriaBuilder().count(rt));
Query q = em.createQuery(cq);
return ((Long) q.getSingleResult()).intValue();
} finally {
em.close();
}
}
}