[news.eclipse.platform] Re: [DataBinding] Cross field validation and Wiz

["Boris Bokowski" <bokowski@xxxxxxxxxx>]

Hi Ovidio,

This looks like a valid use case. Could you please open an enhancement 
request in Bugzilla, and ideally, attach your snippet? (We might want to put 
it into our collection of snippets when/if we can support your use case.)

Thanks
Boris

"Ovidio Mallo" <malloovidio@xxxxxxxxxx> wrote in message 
news:fmrdp5$87l$1@xxxxxxxxxxxxxxxxxxxx
> Hi all!
>
> I have a wizard page in which -- among other things -- the user can
> specify a start date and an end date while, for each date, the month
> and the year can be edited separately using combo boxes (see the
> attached code snippet).
> For implementing that using databinding, I have defined a ComputedValue
> for each date which assembles a Date object from the two SWTObservables
> defining the month and year contained in the combo boxes.
> For validating the wizard page, I have defined another ComputedValue
> which depends on the two date values and returns an IStatus which tells
> whether the start date is before the end date.
> My problem is that I would like to attach this validation status to an
> instance of WizardPageSupport which I am already using for validating
> other parts of the wizard page. However, the WizardPageSupport class
> seems to only support validation status' belonging to bindings. In my
> case, I have a stand-alone validation status value which does not belong
> to any binding.
> So, my question is whether this kind of cross field validation (for
> which no real binding exists) can also be integrated into the
> WizardPageSupport class? Or am I maybe just going the wrong way with my
> approach described above?
>
> I hope my explanation is clear enough. If not, the attached code snippet
> may clarify things.
>
> Thanks in advance for any feedback!
>
> Best regards,
> Ovidio
>


--------------------------------------------------------------------------------


> import java.text.ParseException;
> import java.text.SimpleDateFormat;
> import java.util.Date;
>
> import org.eclipse.core.databinding.DataBindingContext;
> import org.eclipse.core.databinding.observable.Realm;
> import org.eclipse.core.databinding.observable.value.ComputedValue;
> import org.eclipse.core.databinding.observable.value.IObservableValue;
> import org.eclipse.core.databinding.observable.value.IValueChangeListener;
> import org.eclipse.core.databinding.observable.value.ValueChangeEvent;
> import org.eclipse.core.databinding.validation.ValidationStatus;
> import org.eclipse.core.runtime.IStatus;
> import org.eclipse.jface.databinding.swt.SWTObservables;
> import org.eclipse.jface.databinding.wizard.WizardPageSupport;
> import org.eclipse.jface.layout.GridLayoutFactory;
> import org.eclipse.jface.resource.ImageDescriptor;
> import org.eclipse.jface.wizard.IWizard;
> import org.eclipse.jface.wizard.Wizard;
> import org.eclipse.jface.wizard.WizardDialog;
> import org.eclipse.jface.wizard.WizardPage;
> import org.eclipse.swt.SWT;
> import org.eclipse.swt.graphics.Image;
> import org.eclipse.swt.widgets.Combo;
> import org.eclipse.swt.widgets.Composite;
> import org.eclipse.swt.widgets.Display;
> import org.eclipse.swt.widgets.Label;
>
> public class CrossFieldValidation {
>
>  static class FirstWizardPage extends WizardPage {
>
>    private static final String[] MONTHS = {
>      "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"
>    };
>
>    private static final String[] YEARS = { "2006", "2007", "2008", 
> "2009" };
>
>    protected FirstWizardPage() {
>      super("First", "First Page",
>            ImageDescriptor.createFromImage(new Image(Display.getDefault(), 
> 16, 16)));
>    }
>
>    public void createControl(Composite parent) {
>      DataBindingContext dbc = new DataBindingContext();
>      WizardPageSupport.create(this, dbc);
>      Composite composite = new Composite(parent, SWT.NONE);
>
>      final ComputedValue startDateValue = getDateValue(composite, 
> "Start");
>      final ComputedValue endDateValue = getDateValue(composite, "End");
>
>      ComputedValue validationStatus = new ComputedValue(IStatus.class) {
>
>        protected Object calculate() {
>          Date startDate = (Date) startDateValue.getValue();
>          Date endDate = (Date) endDateValue.getValue();
>          if (startDate.before(endDate)) {
>            return ValidationStatus.ok();
>          } else {
>            return ValidationStatus.error("Start date is not before end 
> date.");
>          }
>        }
>      };
>
>      // How to integrate this validation status into a WizardPageSupport 
> class?
>      validationStatus.addValueChangeListener(new IValueChangeListener() {
>
>        public void handleValueChange(ValueChangeEvent event) {
>          IStatus status = (IStatus) event.diff.getNewValue();
>          if (status.isOK()) {
>            setErrorMessage(null);
>            setPageComplete(true);
>          } else {
>            setErrorMessage(status.getMessage());
>            setPageComplete(false);
>          }
>        }
>      });
>
> 
> GridLayoutFactory.swtDefaults().numColumns(4).generateLayout(composite);
>      setControl(composite);
>    }
>
>    private static ComputedValue getDateValue(Composite parent, String 
> startOrEnd) {
>      Label monthLabel = new Label(parent, SWT.NONE);
>      monthLabel.setText(startOrEnd + " month:");
>      Combo monthCombo = new Combo(parent, SWT.READ_ONLY);
>      monthCombo.setItems(MONTHS);
>      monthCombo.select(0);
>
>      Label yearLabel = new Label(parent, SWT.NONE);
>      yearLabel.setText(startOrEnd + " year:");
>      Combo yearCombo = new Combo(parent, SWT.READ_ONLY);
>      yearCombo.setItems(YEARS);
>      yearCombo.select(0);
>
>      final IObservableValue monthValue = 
> SWTObservables.observeText(monthCombo);
>      final IObservableValue yearValue = 
> SWTObservables.observeText(yearCombo);
>
>      return new ComputedValue(Date.class) {
>
>        protected Object calculate() {
>          Date date = null;
>          try {
>            date = new SimpleDateFormat("mm.yyyy")
>                .parse(monthValue.getValue() + "." + yearValue.getValue());
>          } catch (ParseException e) {
>            e.printStackTrace();
>          }
>          return date;
>        }
>      };
>    }
>  }
>
>  static class SampleWizard extends Wizard {
>
>    public void addPages() {
>      addPage(new FirstWizardPage());
>    }
>
>    public String getWindowTitle() {
>      return "Cross field validation";
>    }
>
>    public boolean performFinish() {
>      return true;
>    }
>  }
>
>  public static void main(String[] args) {
>    Display display = new Display();
>    Realm.runWithDefault(SWTObservables.getRealm(display), new Runnable() {
>      public void run() {
>        IWizard wizard = new SampleWizard();
>        WizardDialog dialog = new WizardDialog(null, wizard);
>        dialog.open();
>        Display display = Display.getCurrent();
>        while (dialog.getShell() != null && 
> !dialog.getShell().isDisposed()) {
>          if (!display.readAndDispatch()) {
>            display.sleep();
>          }
>        }
>      }
>    });
>  }
> }
>