How to merge records together - sql

Question

i am able to update the database so for each section a user saves it saves there work fine, in the correct column of the database, but what i am now trying to achieve is instead of saving into a new row, check there studentNumber and if it already has a record in the table (which it will have to to get this far ) update the columns to that record rather than starting a new one
how can i do that ?
currently this is my code :
this is the u.i. where they select the value and press submit
<p:spinner id="ajaxspinner80-100" value="#{editMarkingBean.markSectionTwo.markSectionTwo}"
stepFactor="1" min="80" max="100" disabled="#{formBean.number != 8}">
<p:ajax update="ajaxspinnervalue" process="#this" />
</p:spinner>
the save button
<p:commandButton action="#{editMarkingBean.markSectionTwo}" value="#{bundle.buttonSave}" update=":growl" icon="ui-icon-disk"/>
the backing bean is :
#Named(value = "editMarkingBean")
#ViewScoped
public class EditMarkingController {
private String searchString;
private String ordering;
private String criteria;
private String match;
private Date today;
private String caseMatch;
private int spinnerField;
private Marking markSectionOne;
private Marking studentNumber;
private Marking markSectionTwo;
private MarkingService markingService;
private Marking markToEdit;
#Inject
private MarkingFacade markingFacade;
#PostConstruct
public void init() {
//this.markToEdit = this.markingFacade.find(studentNumber);
this.markSectionTwo = new Marking();
}
public String markSectionTwo() {
this.markingFacade.edit(markSectionTwo);
this.setMessage("Mark Saved");
markSectionTwo = new Marking();
this.setMessage("Mark Saved");
// now navigating to the next page
return "/lecturer/marking/marking-section-three";
}
private void setMessage(String message) {
FacesContext fc = FacesContext.getCurrentInstance();
fc.addMessage(null, new FacesMessage(message, ""));
}
public Marking getMarkSectionTwo() {
return markSectionTwo;
}
public void setMarkSectionTwo(Marking markSectionTwo) {
this.markSectionTwo = markSectionTwo;
}
public String getSearchString() {
return searchString;
}
public void setSearchString(String searchString) {
this.searchString = searchString;
}
public String getOrdering() {
return ordering;
}
public void setOrdering(String ordering) {
this.ordering = ordering;
}
public String getCriteria() {
return criteria;
}
public void setCriteria(String criteria) {
this.criteria = criteria;
}
public String getMatch() {
return match;
}
public void setMatch(String match) {
this.match = match;
}
public Date getToday() {
return today;
}
public void setToday(Date today) {
this.today = today;
}
public String getCaseMatch() {
return caseMatch;
}
public void setCaseMatch(String caseMatch) {
this.caseMatch = caseMatch;
}
public int getSpinnerField() {
return spinnerField;
}
public void setSpinnerField(int spinnerField) {
this.spinnerField = spinnerField;
}
public Marking getMarkSectionOne() {
return markSectionOne;
}
public void setMarkSectionOne(Marking markSectionOne) {
this.markSectionOne = markSectionOne;
}
public Marking getStudentNumber() {
return studentNumber;
}
public void setStudentNumber(Marking studentNumber) {
this.studentNumber = studentNumber;
}
public MarkingService getMarkingService() {
return markingService;
}
public void setMarkingService(MarkingService markingService) {
this.markingService = markingService;
}
public MarkingFacade getMarkingFacade() {
return markingFacade;
}
public void setMarkingFacade(MarkingFacade markingFacade) {
this.markingFacade = markingFacade;
}
}
but currently only adds a new row with the data to the database rather than trying to merge it with the data already contained in the database for a student with a certain student number
how can i achieve this ? thanks guys for your help :)
EDIT :
I have tried :
private Marking markToEdit;
#Inject
private MarkingFacade markingFacade;
#PostConstruct
public void init() {
this.markToEdit = this.markingFacade.find(studentNumber);
//this.markSectionTwo = new Marking();
}
public String markSectionTwo() {
this.markingFacade.edit(markSectionTwo);
this.setMessage("Mark Saved");
// markSectionTwo = new Marking();
//this.setMessage("Mark Saved");
// now navigating to the next page
return "/lecturer/marking/marking-section-three";
}
but get the error :
exception
javax.servlet.ServletException: WELD-000049 Unable to invoke public void sws.control.EditMarkingController.init() on sws.control.EditMarkingController#4109691f
root cause
org.jboss.weld.exceptions.WeldException: WELD-000049 Unable to invoke public void sws.control.EditMarkingController.init() on sws.control.EditMarkingController#4109691f
root cause
java.lang.reflect.InvocationTargetException
root cause
javax.ejb.EJBException
root cause
java.lang.IllegalArgumentException: An instance of a null PK has been incorrectly provided for this find operation.

Answer 1

I use a quite similar approach as yours, but with different names. I'll post it here, so I think you can have some idea.
My way is to check the entity explicitly before merging it.
My JSF CRUD looks like this
xhtml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:p="http://primefaces.org/ui">
<h:head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>DataSource Manager</title>
</h:head>
<h:body>
<h:form id="ds">
<p:spacer height="10" />
<p:fieldset legend="Insert/Edit Data Source">
<p:panel id="insertUpdateForm">
<h:panelGrid columns="2">
<p:outputLabel for="name" value="Data Source Name:" style="width:100px;"/>
<p:inputText id="name" value="#{dataSourceMB.dataSource.name}"/>
<p:outputLabel for="user" value="User:" style="width:100px;"/>
<p:inputText id="user" value="#{dataSourceMB.dataSource.user}"/>
<p:outputLabel for="driver" value="Driver:" style="width:100px;"/>
<p:inputText id="driver" value="#{dataSourceMB.dataSource.driver}" />
</h:panelGrid>
</p:panel>
<p:panel>
<p:commandButton value="Save" action="#{dataSourceMB.saveDataSource}" update="dsList,insertUpdateForm" />
<p:commandButton value="Clear" action="#{dataSourceMB.clearDataSource}" update="insertUpdateForm" />
<p:commandButton value="Test Connection" action="#{dataSourceMB.testConnection}"/>
</p:panel>
</p:fieldset>
<p:spacer height="10" />
<p:fieldset legend="Data Sources">
<p:panel>
<p:dataTable
var="ds"
value="#{dataSourceMB.listDataSources}"
paginator="true" rows="10"
paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}"
rowsPerPageTemplate="10,50,100"
id="dsList">
<p:column headerText="ID">
<h:outputText value="#{ds.id}" />
</p:column>
<p:column headerText="Name">
<h:outputText value="#{ds.name}" />
</p:column>
<p:column headerText="JDBC">
<h:outputText value="#{ds.jdbc} " />
</p:column>
<!-- check http://jqueryui.com/themeroller/ for icons -->
<p:column headerText="" style="width:2%">
<p:commandButton icon="ui-icon-pencil" action="#{dataSourceMB.editDataSource}" title="Edit" update=":ds:insertUpdateForm">
<f:setPropertyActionListener value="#{ds}" target="#{dataSourceMB.selectedDataSource}" />
</p:commandButton>
</p:column>
<p:column headerText="" style="width:2%">
<p:commandButton icon="ui-icon-trash" action="#{dataSourceMB.removeDataSource}" title="Remove" update=":ds:insertUpdateForm,dsList">
<f:setPropertyActionListener value="#{ds}" target="#{dataSourceMB.selectedDataSource}" />
</p:commandButton>
</p:column>
</p:dataTable>
</p:panel>
</p:fieldset>
</h:form>
</h:body>
</html>
my managed bean
import java.io.Serializable;
import java.util.List;
import javax.annotation.PostConstruct;
import javax.ejb.EJB;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import org.apache.log4j.Logger;
import DataSourceEJB;
import JSFUtilEJB;
import DataSource;
#ManagedBean
#ViewScoped
public class DataSourceMB implements Serializable {
private static final long serialVersionUID = 871363306742707990L;
private static Logger log = Logger.getLogger(DataSourceMB.class);
#EJB
private JSFUtilEJB jsfUtilEJB;
#EJB
private DataSourceEJB dataSourceEJB;
private DataSource dataSource;
private DataSource selectedDataSource;
private List<DataSource> listDataSources;
#PostConstruct
public void init() {
try {
this.dataSource = new DataSource();
this.listDataSources = this.dataSourceEJB.listDataSources();
} catch (Exception e) {
jsfUtilEJB.addErrorMessage(e,"Could not list");
}
}
public void removeDataSource(){
try {
this.dataSourceEJB.removeDataSource(this.selectedDataSource);
jsfUtilEJB.addInfoMessage("Removed "+this.selectedDataSource.getName());
if (this.dataSource != null && this.dataSource.getId() != null && this.dataSource.getId().equals(this.selectedDataSource.getId())){
this.dataSource = null;
}
this.listDataSources = this.dataSourceEJB.listDataSources();
} catch (Exception e) {
jsfUtilEJB.addErrorMessage(e,"Could not remove");
}
}
public void saveDataSource(){
try {
this.dataSourceEJB.saveDataSource(this.dataSource);
jsfUtilEJB.addInfoMessage("Saved "+this.dataSource.getName());
this.dataSource = new DataSource();
this.listDataSources = this.dataSourceEJB.listDataSources();
} catch (Exception e) {
jsfUtilEJB.addErrorMessage(e,"Could not save");
}
}
public void editDataSource(){
this.dataSource = this.selectedDataSource;
}
public void clearDataSource(){
this.dataSource = new DataSource();
}
public DataSource getDataSource() {
return dataSource;
}
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public DataSource getSelectedDataSource() {
return selectedDataSource;
}
public void setSelectedDataSource(DataSource selectedDataSource) {
this.selectedDataSource = selectedDataSource;
}
public List<DataSource> getListDataSources() {
return listDataSources;
}
public void setListDataSources(List<DataSource> listDataSources) {
this.listDataSources = listDataSources;
}
}
my EJB
import java.io.IOException;
import java.sql.SQLException;
import java.util.List;
import javax.ejb.Stateless;
import javax.inject.Inject;
import DataSource;
#Stateless
public class DataSourceEJB {
#Inject
private BaseService baseService;
public List<DataSource> listDataSources() {
return this.baseService.getDataSourceDAO().getAll();
}
public void removeDataSource(DataSource ds) throws Exception {
DataSource a = this.baseService.getDataSourceDAO().find(ds.getId());
this.baseService.getDataSourceDAO().delete(a);
}
public void saveDataSource(DataSource ds) throws Exception {
DataSource a = this.baseService.getDataSourceDAO().find(ds.getId());
if (a == null){
this.baseService.getDataSourceDAO().add(ds);
}else{
this.baseService.getDataSourceDAO().edit(ds);
}
}
public DataSource getById(long id) {
return this.baseService.getDataSourceDAO().find(id);
}
public DataSource getByName(String name) {
return this.baseService.getDataSourceDAO().findByName(name);
}
}
DAO
public E find(Long id) {
return (E)entityManager.find(clazz, id);
}
public void add(E entity) throws Exception {
entityManager.persist(entity);
}
public E edit(E entity) throws Exception {
return entityManager.merge(entity);
}
public void delete(E entity) throws Exception {
entityManager.remove(entity);
}