[appengine-java] Re: Not able to save child object in one-to-many relationship
Hi Ravi,
sorry to not have an "easy" workaround for you but the following rules
have proven to be working quite well for us when using GWT + GAEJ +
JDO:
1. No Class hierarchies for JDO Objects going through GWT RPC
2. No JDO modeled 1:n relationships other List (same table)
3. Implicit 1:n relationships setting parent key in child objects
using queries on keys for lookup
In your case this means use a field like this in your Appointment
object:
@Persistent
@Extension(vendorName="datanucleus", key="gae.parent-pk",
value="true")
private String parentKey;
Set this field with the employees key, then you can change both
entities in the same transaction (see entity groups).
Use a key lookup with a filter on the parent key field if you need a
quick count on how many appointments an employee has:
http://code.google.com/intl/de-DE/appengine/docs/java/datastore/queriesandindexes.html#Queries_on_Keys
or a regular query with the same filter to retrieve the actual
appointments.
Hope this helps,
Fred
On 27 Aug., 23:09, hampole wrote:
> Thanks for the info. I looked at the issue and many other people
> having problem of saving child object in a one-to-many relation. I am
> new to this and I don't understand completely. Is there any work-
> around to save a child object. If anyone can show me an example, I
> appreciate. This is really frustrating as this is basic functionality
> in any relational data. In my case, Employee object already exists and
> I want to create a new appointment and associate with the employee
> object. If there is a different way of doing this, please help. This
> has taken quite a lot of time and if this is not available in GWT, I
> don't think I can use Google apps for the development of our
> application. I appreciate any help.
>
> Thanks,
> Ravi
>
> On Aug 27, 1:51 am, Frederik Pfisterer wrote:
>
> > Your problem seems to be related to this open gwt
> > issue:http://code.google.com/p/google-web-toolkit/issues/detail?id=4976
>
> > Please star the issue to raise its attention. The workaround is not
> > using 1:n relationships with GWT + GAE + JDO.
>
> > Cheers,
> > Fred
>
> > On 26 Aug., 23:12, hampole wrote:
>
> > > I am trying to develop GAE application. I am using the latest GWT
> > > SDK(2.0.4) AND App Engine SDK(1.3.6) on Eclipse3.4. I am having
> > > problem insavinga childobject"Appointment" and the parentobject
> > > is "Employee". Each Employee has many appointments and and each
> > > appointment has one employee associated with. I have pasted the Client
> > > code and the server code here. Please help and see what I am missing
> > > here. I tried many different ways without success. When I retrieve the
> > > appointments, the employee is always null. I appreciate any help or
> > > some example that I can try. Thanks.
>
> > > //Client code
> > > public class AppointmentCreateWidget extends Composite {
>
> > > private static AppointmentCreateWidgetUiBinder uiBinder = GWT
> > > .create(AppointmentCreateWidgetUiBinder.class);
>
> > > interface AppointmentCreateWidgetUiBinder extends
> > > UiBinder {
> > > }
>
> > > @UiField Button btnSaveAppointment;
> > > @UiField TextBox tbxSubject;
> > > @UiField ListBox lbxRoom;
> > > @UiField ListBox lbxHost;
> > > @UiField DateBox dbAppointStartDate;
> > > @UiField DateBox dbAppointEndDate;
> > > @UiField ListBox lbxStartTimeHr;
> > > @UiField ListBox lbxEndTimeHr;
> > > @UiField ListBox lbxStartTimeMi;
> > > @UiField ListBox lbxEndTimeMi;
>
> > > private final AppointmentServiceAsync appointService =
> > > (AppointmentServiceAsync) GWT.create(AppointmentService.class);
> > > private final List visitors = new ArrayList();
>
> > > public AppointmentCreateWidget() {
> > > initWidget(uiBinder.createAndBindUi(this))
> > > }
>
> > > @UiHandler("btnSaveAppointment")
> > > void onClick(ClickEvent e) {
> > > addAppointment();
> > > }
>
> > > private void addAppointment() {
> > > String subject = tbxSubject.getText().toUpperCase().trim();
> > > Date startdate = dbAppointStartDate.getValue();
> > > Date enddate = dbAppointEndDate.getValue();
> > > String starttime =
> > > lbxStartTimeHr.getValue(lbxStartTimeHr.getSelectedIndex()).toString()
> > > +
> > >
> > > lbxStartTimeMi.getValue(lbxStartTimeMi.getSelectedIndex());
> > > String endtime =
> > > lbxEndTimeHr.getValue(lbxEndTimeHr.getSelectedIndex()).toString() +
> > > lbxEndTimeMi.getValue(lbxEndTimeMi.getSelectedIndex());
> > > String room =
> > > lbxRoom.getValue(lbxRoom.getSelectedIndex()).toString();
> > > String key = lbxHost.getValue(lbxHost.getSelectedIndex());
> > > DateTimeFormat dateFormat =
> > > DateTimeFormat.getShortDateFormat(
[appengine-java] Re: Not able to save child object in one-to-many relationship
Thanks for the info. I looked at the issue and many other people
having problem of saving child object in a one-to-many relation. I am
new to this and I don't understand completely. Is there any work-
around to save a child object. If anyone can show me an example, I
appreciate. This is really frustrating as this is basic functionality
in any relational data. In my case, Employee object already exists and
I want to create a new appointment and associate with the employee
object. If there is a different way of doing this, please help. This
has taken quite a lot of time and if this is not available in GWT, I
don't think I can use Google apps for the development of our
application. I appreciate any help.
Thanks,
Ravi
On Aug 27, 1:51 am, Frederik Pfisterer wrote:
> Your problem seems to be related to this open gwt
> issue:http://code.google.com/p/google-web-toolkit/issues/detail?id=4976
>
> Please star the issue to raise its attention. The workaround is not
> using 1:n relationships with GWT + GAE + JDO.
>
> Cheers,
> Fred
>
> On 26 Aug., 23:12, hampole wrote:
>
> > I am trying to develop GAE application. I am using the latest GWT
> > SDK(2.0.4) AND App Engine SDK(1.3.6) on Eclipse3.4. I am having
> > problem insavinga childobject"Appointment" and the parentobject
> > is "Employee". Each Employee has many appointments and and each
> > appointment has one employee associated with. I have pasted the Client
> > code and the server code here. Please help and see what I am missing
> > here. I tried many different ways without success. When I retrieve the
> > appointments, the employee is always null. I appreciate any help or
> > some example that I can try. Thanks.
>
> > //Client code
> > public class AppointmentCreateWidget extends Composite {
>
> > private static AppointmentCreateWidgetUiBinder uiBinder = GWT
> > .create(AppointmentCreateWidgetUiBinder.class);
>
> > interface AppointmentCreateWidgetUiBinder extends
> > UiBinder {
> > }
>
> > @UiField Button btnSaveAppointment;
> > @UiField TextBox tbxSubject;
> > @UiField ListBox lbxRoom;
> > @UiField ListBox lbxHost;
> > @UiField DateBox dbAppointStartDate;
> > @UiField DateBox dbAppointEndDate;
> > @UiField ListBox lbxStartTimeHr;
> > @UiField ListBox lbxEndTimeHr;
> > @UiField ListBox lbxStartTimeMi;
> > @UiField ListBox lbxEndTimeMi;
>
> > private final AppointmentServiceAsync appointService =
> > (AppointmentServiceAsync) GWT.create(AppointmentService.class);
> > private final List visitors = new ArrayList();
>
> > public AppointmentCreateWidget() {
> > initWidget(uiBinder.createAndBindUi(this))
> > }
>
> > @UiHandler("btnSaveAppointment")
> > void onClick(ClickEvent e) {
> > addAppointment();
> > }
>
> > private void addAppointment() {
> > String subject = tbxSubject.getText().toUpperCase().trim();
> > Date startdate = dbAppointStartDate.getValue();
> > Date enddate = dbAppointEndDate.getValue();
> > String starttime =
> > lbxStartTimeHr.getValue(lbxStartTimeHr.getSelectedIndex()).toString()
> > +
> > lbxStartTimeMi.getValue(lbxStartTimeMi.getSelectedIndex());
> > String endtime =
> > lbxEndTimeHr.getValue(lbxEndTimeHr.getSelectedIndex()).toString() +
> > lbxEndTimeMi.getValue(lbxEndTimeMi.getSelectedIndex());
> > String room =
> > lbxRoom.getValue(lbxRoom.getSelectedIndex()).toString();
> > String key = lbxHost.getValue(lbxHost.getSelectedIndex());
> > DateTimeFormat dateFormat = DateTimeFormat.getShortDateFormat();
>
> > try {
> > createAppointment(subject, startdate, enddate,
> > starttime,
> > endtime, key, visitors);
> > }
> > catch(Exception ex) {
> > Window.alert("Save Appointment failed: " + ex.toString());
> > }
> > }
>
> > private void createAppointment(String subject, Date startdate, Date
> > enddate, String starttime, String endtime, String empID, List
> > visitor) {
> > appointService.addAppointment(subject,startdate, enddate,
> > starttime, endtime, empID, visitor, new AsyncCallback() {
> > public void onFailure(Throwable error) {
> > Window.alert("Unable to create Appointment." +
> > error.getMessage());
> > }
> > public void onSuccess(Void ignore) {
> > }
> > });
> > }
>
> > }
>
> > //ServiceImpl
> > public class AppointmentServiceImpl extends RemoteServiceServlet
> > implements AppointmentService {
> > /**
> > *
> > */
> > private static final long serialVersionUID = 1L;
>
> > public void addAppointment(String subject, Date appointStartDate,
> >
[appengine-java] Re: Not able to save child object in one-to-many relationship
Your problem seems to be related to this open gwt issue:
http://code.google.com/p/google-web-toolkit/issues/detail?id=4976
Please star the issue to raise its attention. The workaround is not
using 1:n relationships with GWT + GAE + JDO.
Cheers,
Fred
On 26 Aug., 23:12, hampole wrote:
> I am trying to develop GAE application. I am using the latest GWT
> SDK(2.0.4) AND App Engine SDK(1.3.6) on Eclipse3.4. I am having
> problem in saving a child object "Appointment" and the parent object
> is "Employee". Each Employee has many appointments and and each
> appointment has one employee associated with. I have pasted the Client
> code and the server code here. Please help and see what I am missing
> here. I tried many different ways without success. When I retrieve the
> appointments, the employee is always null. I appreciate any help or
> some example that I can try. Thanks.
>
> //Client code
> public class AppointmentCreateWidget extends Composite {
>
> private static AppointmentCreateWidgetUiBinder uiBinder = GWT
> .create(AppointmentCreateWidgetUiBinder.class);
>
> interface AppointmentCreateWidgetUiBinder extends
> UiBinder {
> }
>
> @UiField Button btnSaveAppointment;
> @UiField TextBox tbxSubject;
> @UiField ListBox lbxRoom;
> @UiField ListBox lbxHost;
> @UiField DateBox dbAppointStartDate;
> @UiField DateBox dbAppointEndDate;
> @UiField ListBox lbxStartTimeHr;
> @UiField ListBox lbxEndTimeHr;
> @UiField ListBox lbxStartTimeMi;
> @UiField ListBox lbxEndTimeMi;
>
> private final AppointmentServiceAsync appointService =
> (AppointmentServiceAsync) GWT.create(AppointmentService.class);
> private final List visitors = new ArrayList();
>
> public AppointmentCreateWidget() {
> initWidget(uiBinder.createAndBindUi(this))
> }
>
> @UiHandler("btnSaveAppointment")
> void onClick(ClickEvent e) {
> addAppointment();
> }
>
> private void addAppointment() {
> String subject = tbxSubject.getText().toUpperCase().trim();
> Date startdate = dbAppointStartDate.getValue();
> Date enddate = dbAppointEndDate.getValue();
> String starttime =
> lbxStartTimeHr.getValue(lbxStartTimeHr.getSelectedIndex()).toString()
> +
> lbxStartTimeMi.getValue(lbxStartTimeMi.getSelectedIndex());
> String endtime =
> lbxEndTimeHr.getValue(lbxEndTimeHr.getSelectedIndex()).toString() +
> lbxEndTimeMi.getValue(lbxEndTimeMi.getSelectedIndex());
> String room =
> lbxRoom.getValue(lbxRoom.getSelectedIndex()).toString();
> String key = lbxHost.getValue(lbxHost.getSelectedIndex());
> DateTimeFormat dateFormat = DateTimeFormat.getShortDateFormat();
>
> try {
> createAppointment(subject, startdate, enddate, starttime,
> endtime, key, visitors);
> }
> catch(Exception ex) {
> Window.alert("Save Appointment failed: " + ex.toString());
> }
> }
>
> private void createAppointment(String subject, Date startdate, Date
> enddate, String starttime, String endtime, String empID, List
> visitor) {
> appointService.addAppointment(subject,startdate, enddate,
> starttime, endtime, empID, visitor, new AsyncCallback() {
> public void onFailure(Throwable error) {
> Window.alert("Unable to create Appointment." +
> error.getMessage());
> }
> public void onSuccess(Void ignore) {
> }
> });
> }
>
> }
>
> //ServiceImpl
> public class AppointmentServiceImpl extends RemoteServiceServlet
> implements AppointmentService {
> /**
> *
> */
> private static final long serialVersionUID = 1L;
>
> public void addAppointment(String subject, Date appointStartDate,
> Date appointEndDate, String startTime, String endTime, String empID,
> List visitors) throws NotLoggedInException {
> PersistenceManager pm = getPersistenceManager();
> //get employee
> Employee emp = pm.getObjectById(Employee.class, empID);
>
> Appointment newAppoint = new Appointment(subject,
> appointStartDate, appointEndDate, startTime, endTime);
> newAppoint.setVisitors(visitors);
> newAppoint.setEmployee(emp);
> emp.getAppointments().add(newAppoint);
>
> try {
> pm.makePersistent(emp);
> } finally {
> pm.close();
> }
> }
>
> private PersistenceManager getPersistenceManager() {
> return PMF.get().getPersistenceManager();
> }
>
> }
>
> //Employee Bean
> @PersistenceCapable(identityType = IdentityType.APPLICATION,
> detachable = "true")
> public class Employee implements IsSerializable, IValidatable {
>
> @PrimaryKey
> @Persistent(valueStrategy = IdGenerator
