jsf - Changes not reflected in JPA entities after updating in h:dataTable

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jsf - Changes not reflected in JPA entities after updating in h:dataTable

posted Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

jsf - Changes not reflected in JPA entities after updating in h:dataTable

I am working with Eclipse and Glassfish 3.0. Pretty new to this technology although I have done similar things before. Very simple really got a datatable bound to a backing bean. Add methods and remove methods i have covered - the problem lies with the update method I am calling. I cannot seem to see the changes being picked up in the component (HtmlInputText) never mind passing the data back to the table.

My code for the data table is below (and the jsf page)

<html 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">

<f:loadBundle basename="resources.application" var="msg"/>

<head>
    <title><h:outputText value="#{msg.welcomeTitle}" /></title>
</head>
<body>
 <h:form id="mainform">

  <h:dataTable var="row"  border="0" value="#{beanCategory.collection}" binding="#{beanCategory.datatable}">

    <f:facet name="header">
        <h:outputText value="Categories"/>
    </f:facet>
    <h:column>
        <f:facet name="header">
            <h:outputText value="Description"/>
        </f:facet> 

            <h:inputText id="input1" value="#{row.description}" valueChangeListener="#{row.inputChanged}"/>


        </h:column>
    <h:column>
        <f:facet name="header">
            <h:outputText value="Id"/>
        </f:facet>
        <h:outputText id="id" value="#{row.id}"/>
    </h:column>
    <h:column>
            <h:commandButton value="Delete" type="submit" action="#{beanCategory.remove}">

                <f:setPropertyActionListener target="#{beanCategory.selectedcategory}" value="#{row}"/>
            </h:commandButton>
            <h:commandButton value="Save" action="#{beanCategory.update}"
                >
                <f:setPropertyActionListener
                    target="#{beanCategory.selectedcategory}" value="#{row}" />

            </h:commandButton>
        </h:column>
</h:dataTable>

<h:inputText id="text1"></h:inputText>  <h:commandButton action="#{beanCategory.addCategory}" value="Add" type="submit" id="submitbutton">

</h:commandButton>
<br/><br/>
Messages    

<h:messages></h:messages><br /><br />

</h:form>   
 </body>
</html>

Backing Bean is here

package net.bssuk.timesheets.controller;

import java.io.Serializable;

import java.util.List;

import javax.faces.component.UIInput;
import javax.faces.component.html.HtmlDataTable;
import javax.faces.context.FacesContext;

import javax.persistence.*;

import net.bssuk.timesheets.model.Category;

@javax.inject.Named("beanCategory")
@javax.enterprise.context.SessionScoped

public class BeanCategory implements Serializable {

private List<Category> collection;
private EntityManagerFactory emf;
private EntityManager em;
private int selectedid;
private Category selectedcategory;
private HtmlDataTable datatable;

private static final long serialVersionUID = 1L;

public BeanCategory() {
    // TODO Auto-generated constructor stub

    System.out.println("Bean Constructor");

}

public String addCategory() {
    try {
        this.emf = Persistence.createEntityManagerFactory("timesheets1");
        System.out.println("Changed - Now attempting to add");
        System.out.println("Ready to do cateogory");
        Category category = new Category();

        FacesContext context = FacesContext.getCurrentInstance();
        UIInput input = (UIInput) context.getViewRoot().findComponent(
                "mainform:text1");

        String value = input.getValue().toString();
        if (value != null) {
            category.setDescription(input.getValue().toString());
        } else {
            category.setDescription("Was null");
        }
        this.em = this.emf.createEntityManager();
        EntityTransaction tx = em.getTransaction();
        tx.begin();
        em.persist(category);
        tx.commit();
        em.close();
        emf.close();
        // return "index.xhtml";
    } catch (Exception e) {
        e.printStackTrace();
    }
    return "return.html";
}

public String remove() {
    try {
        this.emf = Persistence.createEntityManagerFactory("timesheets1");
        System.out.println("Getting Collection");
        this.em = this.emf.createEntityManager();

        FacesContext context = FacesContext.getCurrentInstance();

        System.out.println("Number found is " + this.selectedid);

        if (selectedcategory != null) {

            System.out.println("removing "+selectedcategory.getId()+" - " +selectedcategory.getDescription());
            EntityTransaction tx = em.getTransaction();
            tx.begin();
            System.out.println("Merging..");
            this.em.merge(selectedcategory);
            System.out.println("removing...");
            this.em.remove(selectedcategory);
            tx.commit();
            em.close();
            emf.close();
        }else{
            System.out.println("Not found");
        }
        return "index.xhtml";
    } catch (Exception e) {
        e.printStackTrace();
        return "index.xhtml";
    }

}

public String update() {
    try {
        this.emf = Persistence.createEntityManagerFactory("timesheets1");
        System.out.println("Update Getting Collection");
        Category category = (Category) getDatatable().getRowData();

        FacesContext context = FacesContext.getCurrentInstance();
        System.out.println("PHASE ID="+context.getCurrentPhaseId().toString());

        if (category != null) {
            // DESCRIPTION VALUE BELOW IS ALWAYS OLD VALUE (IE DATA IN DATABASE)
            System.out.println("updating "+category.getId()+" - " +category.getDescription());

            this.em = this.emf.createEntityManager();
            EntityTransaction tx = em.getTransaction();
            tx.begin();
            em.merge(category);
            tx.commit();
            em.close();
            emf.close();
        }else{
            System.out.println("Not found");
        }
        return "index.xhtml";
    } catch (Exception e) {
        e.printStackTrace();
        return "";
    }
}

public void setCollection(List<Category> collection) {
    this.collection = collection;
}

public List<Category> getCollection() {
    // this.emf=Persistence.createEntityManagerFactory("timesheets1");
    // System.out.println("Getting Collection");
    try {
        this.emf = Persistence.createEntityManagerFactory("timesheets1");
        this.em = this.emf.createEntityManager();
        Query query = this.em.createNamedQuery("findAll");
        this.collection = query.getResultList();
        return this.collection;
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}

public void setSelectedid(int id) {
    this.selectedid=id;
}

public void setSelectedcategory(Category selectedcategory) {
    this.selectedcategory = selectedcategory;
}

public HtmlDataTable getDatatable() {
    return datatable;
}

public void setDatatable(HtmlDataTable datatable) {
    this.datatable = datatable;
}
public Category getSelectedcategory() {
return selectedcategory;
 }



}

My Mapped entity for JPA is here

package net.bssuk.timesheets.model;
import java.io.Serializable;
import javax.persistence.*;


/**
 * The persistent class for the CATEGORIES database table.
 * 
*/
@Entity
@Table(name="CATEGORIES")
@NamedQuery(name="findAll", query = "SELECT c from Category c")
public class Category implements Serializable {
private static final long serialVersionUID = 1L;

private String description;

@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;

public Category() {
}

public String getDescription() {
    return this.description;
}

public void setDescription(String description) {
    this.description = description;
}

public int getId() {
    return this.id;
}

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

}

OK - Updated my code to follow example. I have tried to incorporate an EJB into the scenario as follows

package net.bssuk.timesheets.ejb;

import java.util.List;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import net.bssuk.timesheets.model.Category;
@Stateless
public class CategoryEJB implements CategoryEJBRemote {

@PersistenceContext(unitName="timesheets1")
private EntityManager em;

@Override
public List<Category> findCategories() {
    // TODO Auto-generated method stub
    System.out.println("find categories");
    Query query = em.createNamedQuery("findAll");
    return query.getResultList();
}

@Override
public Category createCategory(Category category) {
    // TODO Auto-generated method stub
    em.persist(category);
    return category;
}

@Override
public Category udpateCategory(Category category) {
    // TODO Auto-generated method stub
    return em.merge(category);
}

@Override
public void deleteCategory(Category category) {
    // TODO Auto-generated method stub
        em.remove(em.merge(category));
}

}

My EJB is below

package net.bssuk.timesheets.ejb;

import java.util.List;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import net.bssuk.timesheets.model.Category;
@Stateless
public class CategoryEJB implements CategoryEJBRemote {

@PersistenceContext(unitName="timesheets1")
private EntityManager em;

@Override
public List<Category> findCategories() {
    // TODO Auto-generated method stub
    System.out.println("find categories");
    Query query = em.createNamedQuery("findAll");
    return query.getResultList();
}

@Override
public Category createCategory(Category category) {
    // TODO Auto-generated method stub
    em.persist(category);
    return category;
}

@Override
public Category udpateCategory(Category category) {
    // TODO Auto-generated method stub
    return em.merge(category);
}

@Override
public void deleteCategory(Category category) {
    // TODO Auto-generated method stub
        em.remove(em.merge(category));
}

}

Can anyone suggest if this sort of looks ok? Or have I completely lost the plot with it!

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1 Reply

深蓝 · Answer 1 · 2021-10-23T18:42:16+0000

Look,

<h:dataTable var="row"  border="0" value="#{beanCategory.collection}" binding="#{beanCategory.datatable}">

and

public List<Category> getCollection() {
    // this.emf=Persistence.createEntityManagerFactory("timesheets1");
    // System.out.println("Getting Collection");
    try {
        this.emf = Persistence.createEntityManagerFactory("timesheets1");
        this.em = this.emf.createEntityManager();
        Query query = this.em.createNamedQuery("findAll");
        this.collection = query.getResultList();
        return this.collection;
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}

You're loading the list inside a getter method. This is a very bad idea. A getter should solely be an access point to the bean property, not to do some business job. A getter can be called multiple times during bean's life. The DB will be hit on every call and the local collection property which was been updated by JSF during form submit will be overwritten again at a later point. This makes no sense.

Do the business job in the (post)constructor method or action(listener) methods. Definitely not in a getter. Here's a minimum kickoff example with some code improvements:

<h:dataTable value="#{bean.categories}" var="category">
    <h:column>
        <h:inputText value="#{category.description}" />
    </h:column>
    <h:column>
        <h:outputText value="#{category.id}" />
    </h:column>
    <h:column>
        <h:commandButton value="Delete" action="#{bean.delete(category)}" />
        <h:commandButton value="Save" action="#{bean.update(category)}" />
    </h:column>
</h:dataTable>
<h:inputText value="#{bean.newCategory.description}" />
<h:commandButton value="Add" action="#{bean.add}" />

(note that passing arguments in EL is supported since EL 2.2 (part of Servlet 3.0), Glassfish 3 is a Servlet 3.0 container, so it should definitely support it when web.xml is properly declared conform Servlet 3.0 spec)

with

@ManagedBean
@ViewScoped // Definitely don't use session scoped. I'm not sure about CDI approach, so here's JSF example.
public class Bean {

    private List<Category> categories;
    private Category newCategory;

    @EJB
    private CategoryService categoryService;

    @PostConstruct
    public void init() {
        categories = categoryService.list();
        newCategory = new Category();
    }

    public void add() {
        categoryService.add(newCategory);
        init();
    }

    public void delete(Category category) {
        categoryService.delete(category);
        init();
    }

    public void update(Category category) {
        categoryService.update(category);
        init();
    }

    public List<Category> getCategories() {
        return categories;
    }

    public Category getNewCategory() {
        return newCategory;
    }

}

That should be it. See also:

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jsf - Changes not reflected in JPA entities after updating in h:dataTable

jsf - Changes not reflected in JPA entities after updating in h:dataTable

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