Persisting the abstract

[Cesar Sportore]

Hi guys,

I don't know if this is the appropriate place for this topic, but here I go:

I've been trying to make things a little more OO, so I used an abstract class to define a few default attributes and methods(getters/setters) for the subclasses, but I'm not used to work with inheritance on a JPA context and couldn't access/persist the fields belonging to the super class.
I've tried many things to solve my problem, but none of them worked out properly. This code I'm posting here is my current version of my workaround trials.

PRODUTO.class

package model;

import java.util.Calendar;
import java.util.GregorianCalendar;

import javax.persistence.MappedSuperclass;

@MappedSuperclass
public abstract class Produto {

	protected String nome;
	protected Double preco;
	protected Calendar dataDeCompra = new GregorianCalendar();

	public String getNome() {
		return nome;
	}

	public void setNome(String nome) {
		this.nome = nome;
	}

	public Double getPreco() {
		return preco;
	}

	public void setPreco(Double preco) {
		this.preco = preco;
	}

	public Calendar getDataDeCompra() {
		return dataDeCompra;
	}

	public void setDataDeCompra(Calendar dataDeCompra) {
		this.dataDeCompra = dataDeCompra;
	}
}

LIVRO.class

package model.entities;

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

import model.Produto;

@Entity
public class Livro extends Produto {
	@Id
	@GeneratedValue
	private Integer id;
	private static final Integer idCategoria = 0001;
	private String autor;
	private String editora;

	public String getAutor() {
		return autor;
	}

	public void setAutor(String autor) {
		this.autor = autor;
	}

	public String getEditora() {
		return editora;
	}

	public void setEditora(String editora) {
		this.editora = editora;
	}

	public static Integer getIdcategoria() {
		return idCategoria;
	}

	public Integer getId() {
		return id;
	}

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

}

formulario-novo-livro.xhtml = this one is to register a new Livro(book) to the DB.

<ui:composition 
	xmlns="http://www.w3.org/1999/xhtml"
	xmlns:ui="http://java.sun.com/jsf/facelets"
	xmlns:h="http://java.sun.com/jsf/html"
	xmlns:f="http://java.sun.com/jsf/core">

<h:inputHidden value="#{livroBean.livro.id}"/>
<h:panelGrid columns="3">
	<h:outputLabel value="Titulo: " for="campo-titulo"/>
	<h:inputText 
			id="campo-titulo"
			required="true"
			requiredMessage="*campo obrigatorio"
			value="#{livroBean.livro.nome}">
	</h:inputText>
	<h:message for="campo-titulo"/>
	
	<h:outputLabel value="Autor(a): " for="campo-autor"/>
	<h:inputText
			id="campo-autor"
			required="true"
			requiredMessage="*campo obrigatorio"
			value="#{livroBean.livro.autor}">
	</h:inputText>
	<h:message for="campo-autor"/>
	
	<h:outputLabel value="Editora: " for="campo-editora"/>
	<h:inputText
			id="campo-editora"
			required="true"
			requiredMessage="*campo obrigatorio"
			value="#{livroBean.livro.editora}">
	</h:inputText>
	<h:message for="campo-editora"/>
	
	<h:outputLabel value="Preco: " for="campo-preco"/>
	<h:inputText
			id="campo-preco"
			required="true"
			requiredMessage="*campo obrigatorio"
			value="#{livroBean.livro.preco}">
	</h:inputText>
	<h:message for="campo-preco"/>
	
	<h:outputLabel value="Data de Compra: " for="campo-data-compra"/>
	<h:inputText
			id="campo-data-compra"
			required="true"
			requiredMessage="*campo obrigatorio"
			value="#{livroBean.livro.dataDeCompra.time}">
			<f:convertDateTime pattern="dd/MM/yyyy"/>
	</h:inputText>
	<h:message for="campo-data-compra"/>
	
	<h:commandButton value="Adicionar">
		<f:ajax
			event="click"
			execute="@form"
			listener="#{livroBean.adiciona}"
			render="@all"/>
	</h:commandButton>
	
</h:panelGrid>
	
</ui:composition>

lista-de-livros = this one is to display all the books on the web page.

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
	xmlns:ui="http://java.sun.com/jsf/facelets"
	xmlns:h="http://java.sun.com/jsf/html"
	xmlns:f="http://java.sun.com/jsf/core">

<h2>Lista de Livros</h2>
<h:panelGroup rendered="#{not empty livroBean.livros}">

	<h:dataTable
			id="tabela-livros"
			value="#{livroBean.livros}"
			var="livro"
			styleClass="dados"
			rowClasses="par, impar">
			
		<h:column>
			<f:facet name="header">
				<h:outputText value="ID"/>
			</f:facet>
			#{livro.id}
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Titulo"/>
			</f:facet>
			#{livro.nome}
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Autor(a)"/>
			</f:facet>
			#{livro.autor}
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Editora"/>
			</f:facet>
			#{livro.editora}
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Preco"/>
			</f:facet>
			#{livro.preco}
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Data de Compra"/>
			</f:facet>
				<h:outputText value="#{livro.dataDeCompra}">
					<f:convertDateTime pattern="dd/MM/yyyy"/>
				</h:outputText>
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Alterar"/>
			</f:facet>
			<f:ajax
				event="click"
				render="@form"
				listener="#{livroBean.preparaAlteracao}">
					<h:commandLink>
						<f:param name="id" value="#{livro.id}"/>
						Alterar
					</h:commandLink>
			</f:ajax>
		</h:column>
		
		<h:column>
			<f:facet name="header">
				<h:outputText value="Remover"/>
			</f:facet>
			<f:ajax
				event="click"
				render="@form"
				listener="#{livroBean.remove}">
					<h:commandLink >
						<f:param name="id" value="#{livro.id}"/>
						Remover
					</h:commandLink>	
			</f:ajax>
		</h:column>
	
	</h:dataTable>
</h:panelGroup>
</ui:composition>

Thanks in advance to all who wish to help!

[James Sutherland]

What error/issue do you get?

Ensure the Produto class is listed in your persistence.xml.

Try enabling logging on finest to debug issues.

[Cesar Sportore]

Hi James!

Well, most of the times were Servlet Exceptions. Now the h:commandbutton simply won't work.
There was a time when I annotated the PRODUTO.class with @MappedSuperclass and I got a Conversion Exception at the Calendar field.
I'm pretty much lost, so I don't know if I can provide more useful info. What is the "enabling logging on finest"?

[Emanuel Kadziela]

Set your log level to "all" or "trace" or at least "debug" so you can capture everything that is happening.

Who is your JPA vendor (Hibernate)? What does your persistence.xml file look like? What's the rest of the application configuration look like?

[Cesar Sportore]

I've checked my log level and it's at FINEST level.

Yes, I use Hibernate. Here is an image of one thing that caught my attention.

And here are the files you asked for:

LivroRepository.class

package model.repositories;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;

import model.entities.Livro;

public class LivroRepository {

	private EntityManager manager;

	public LivroRepository(EntityManager manager) {
		this.manager = manager;
	}

	public void adiciona(Livro livro) {
		this.manager.persist(livro);
	}

	public void remove(Long id) {
		Livro livro = this.procura(id);
		this.manager.remove(livro);
	}

	public Livro procura(Long id) {
		return this.manager.find(Livro.class, id);
	}

	public Livro atualiza(Livro livro) {
		return this.manager.merge(livro);
	}

	@SuppressWarnings("unchecked")
	public List<Livro> getLista() {
		Query query = this.manager.createQuery("select x from Livro x");
		return query.getResultList();
	}
}

package managedbeans;

import java.util.List;
import java.util.Map;

import javax.faces.bean.ManagedBean;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.persistence.EntityManager;
import javax.servlet.http.HttpServletRequest;

import model.entities.Livro;
import model.repositories.LivroRepository;

@ManagedBean
public class LivroBean {
	private Livro livro = new Livro();
	private List<Livro> livros;

	public void adiciona() {
		EntityManager manager = this.getManager();
		LivroRepository repository = new LivroRepository(manager);

		if (this.livro.getId() == null) {
			repository.adiciona(this.livro);
		} else {
			repository.atualiza(this.livro);
		}
		this.livro = new Livro();
		this.livros = null;
	}

	public void preparaAlteracao() {
		Map<String, String> params = FacesContext.getCurrentInstance()
				.getExternalContext().getRequestParameterMap();
		Long id = Long.parseLong(params.get("id"));
		EntityManager manager = this.getManager();
		LivroRepository repository = new LivroRepository(manager);
		this.livro = repository.procura(id);
	}

	public void remove() {
		Map<String, String> params = FacesContext.getCurrentInstance()
				.getExternalContext().getRequestParameterMap();
		Long id = Long.parseLong(params.get("id"));
		EntityManager manager = this.getManager();
		LivroRepository repository = new LivroRepository(manager);
		repository.remove(id);
		this.livros = null;
	}

	public List<Livro> getLivros() {
		if (this.livros == null) {
			EntityManager manager = this.getManager();
			LivroRepository repository = new LivroRepository(manager);
			this.livros = repository.getLista();
		}
		return this.livros;
	}

	private EntityManager getManager() {
		FacesContext fc = FacesContext.getCurrentInstance();
		ExternalContext ec = fc.getExternalContext();
		HttpServletRequest request = (HttpServletRequest) ec.getRequest();
		return (EntityManager) request.getAttribute("EntityManager");
	}

	public Livro getLivro() {
		return livro;
	}

	public void setLivro(Livro livro) {
		this.livro = livro;
	}

	public void setLivros(List<Livro> livros) {
		this.livros = livros;
	}

}

According to the Debugger, those are my classes that trigger the error. I'm pretty new to Java, so I don't know anything about debugging and stuff. If you guys have suggestions regarding literature that could help me I'd be very pleased!

Here is the persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 
    xmlns="http://java.sun.com/xml/ns/persistence" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
    				http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    				
	<persistence-unit name="LojaVirtual-PU" transaction-type="RESOURCE_LOCAL">
	    <provider>org.hibernate.ejb.HibernatePersistence</provider>
	    <properties>
	        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
	        <property name="hibernate.hbm2ddl.auto" value="create"/>
	        <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
	        <property name="javax.persistence.jdbc.user" value="user"/>
	        <property name="javax.persistence.jdbc.password" value="password" />
	        <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/LojaVirtual-DB"/>
	    </properties>
	    
	</persistence-unit>
</persistence>

Thanks for all the help!

[Emanuel Kadziela]

You say "according to the Debugger" - what Debugger?

Are there any log files? Log output where the errors are printed? Those would be on the app server side, java logs with java errors. What is your application server (Tomcat)? You need to find, copy and paste the entire stack traces of your exceptions if you want someone to be able to help you. Just telling us "I'm getting exceptions" or "my stuff is not working" is not enough.