Eclipse - binding (from Eclipse 3.3)

JFace-Data-Binding from Eclipse 3.3

In a thought example, a model shall consist of these three attributes:

• surname
  
• first name
  
• date of birth
  

The binding-method can be implemented for example in the MyFormPart-class.

private void bind(model) {
   m_bindingContext = new DataBindingContext();
 
   Binding binding;
 
   binding = m_bindingContext.bindValue(SWTObservables.observeText(m_lastnameTxt,
             SWT.Modify), BeansObservables.observeValue(model, MyModel.PROP_LASTNAME), null, null);
 
   binding = m_bindingContext.bindValue(SWTObservables.observeText(m_firstnameTxt,
             SWT.Modify), BeansObservables.observeValue(model, MyModel.PROP_FIRSTNAME), null, null);
 
   initUpdateStrategy();
   binding = m_bindingContext.bindValue(SWTObservables.observeText(m_birthdateTxt,
             SWT.Modify), BeansObservables.observeValue(model, MyModel.PROP_BIRTHDAY), 
             m_targetToModelStrategy, m_modelToTargetStrategy);
}

The call occurs in the setFormInput(..) method:

@Override
public boolean setFormInput(final Object input){
   MyModel model = (MyModel)input;
   bind(model);
}

This method is called up from the bind()-method, so it must be reachable for this one.

private void initUpdateStrategy(){
   IConverter date2StrConverter = new IConverter() {
 
      public Object convert(Object fromObject) {
         assert fromObject instanceof Date;
         Date date = (Date) fromObject;
         SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy");
         return sdf.format(date);
      }
 
      public Object getFromType() {
         return Date.class;
      }
 
      public Object getToType() {
         return String.class;
      }     
   };
 
   IConverter str2DateConverter = new IConverter() {
      public Object convert(Object fromObject) {
         assert fromObject instanceof String;
         String str = (String) fromObject;
         SimpleDateFormat sd = new SimpleDateFormat("dd.MM.yyyy"); 
         Date date = null;
         try {
            Date newDate = sd.parse(dateString);
         } catch (Exception e) {
            e.printstacktrace();
         }
         return date;
      }
 
      public Object getFromType() {
         return String.class;
      }
 
      public Object getToType() {
         return Date.class;
      }            
   };
 
   IValidator dateFormatValidator = new IValidator() {
      public IStatus validate(Object value) {
         assert value instanceof String;
         IStatus status = Status.OK_STATUS;
 
         String str = (String) value;
         if (str.matches("\\d{2}\\.\\d{2}\\.\\d{4}")) {
            try {
               DateConv.toDate(str);
            }catch(IllegalArgumentException e) {
               status = ValidationStatus.error("Wrong Date", e);
            }
         }else
            status = ValidationStatus.error("Wrong Format");
         return status;
      }       
   };
 
   IValidator dateBizValidator = new IValidator() {
      public IStatus validate(Object value) {
         IStatus status = Status.OK_STATUS;
 
         Date inspect = (Date) value;
         if (null != inspect) {
            final Date today = new Date();
            if (today.before(inspect)) 
               status = ValidationStatus.error("Datum muss vor heute liegen!");
         }
 
         return status;
      }            
   };
 
   m_modelToTargetUpdateStrategy1 = new UpdateValueStrategy();
// oder bei spezieller Policy (Default: UpdateValueStrategy.POLICYUPDATE)
// m_modelToTargetUpdateStrategy1 = new UpdateValueStrategy(UpdateValueStrategy.NEVER);
   m_modelToTargetUpdateStrategy1.setConverter(date2StrConverter);
   m_targetToModelUpdateStrategy = new UpdateValueStrategy();
   m_targetToModelUpdateStrategy.setConverter(str2DateConverter);
   m_targetToModelUpdateStrategy.setAfterGetValidator(dateFormatValidator);
   m_targetToModelUpdateStrategy.setBeforeSetValidator(dateBizValidator);
}

package com.sowas.demo;
 
import java.beans.PropertyChangeListener;
 
public class MyModel {
   String PROP_LASTNAME  = "lastname"; 
   String PROP_FIRSTNAME = "firstname";
   String PROP_BIRTHDAY  = "birthday"; 
   private final PropertyChangeSupport m_propertyChangeSupport = new PropertyChangeSupport();
 
   private String m_lastname;
   private String m_firstname;
   private Date   m_birthday;
 
   public MyModel(String lastname, String firstname, Date birthday) {
      m_lastname = lastname;
      m_firstname = firstname;
      m_birthday = birthday;
   }
 
   public String getLastname(){
      return m_lastname;
   }
 
   public void setLastname(final String newValue){
      String oldValue = getLastname();
      m_lastname = newValue;
      firePropertyChange(PROP_LASTNAME, oldValue, newValue);
   }
 
   public String getFirstname(){
      return m_firstname;
   }
 
   public void setFirstname(final String newValue){
      String oldValue = getFirstname();
      m_firstname = newValue;
      firePropertyChange(PROP_FIRSTNAME, oldValue, newValue);
   }
 
   public Date getBirthday(){
      return m_birthday;
   }
 
   public void setBirthday(final Date newValue){
      Date oldValue = getBirthday();
      m_birthday = newValue;
      firePropertyChange(PROP_BIRTHDAY, oldValue, newValue);
   }
 
   protected boolean firePropertyChange(final String propertyName, final Object oldValue, final Object newValue) {
      return m_propertyChangeSupport.firePropertyChange(propertyName, oldValue, newValue);
   }
 
 
   public void addPropertyChangeListener(final PropertyChangeListener listener, final String... propertyNames) {
      m_propertyChangeSupport.addPropertyChangeListener(listener, propertyNames);
   }
 
   public void addPropertyChangeListener(final PropertyChangeListener listener) {
      m_propertyChangeSupport.addPropertyChangeListener(listener);
   }
 
   public void removePropertyChangeListener(final PropertyChangeListener listener, final String... propertyNames) {
      m_propertyChangeSupport.removePropertyChangeListener(listener, propertyNames);
   }
 
   public void removePropertyChangeListener(final PropertyChangeListener listener) {
      m_propertyChangeSupport.removePropertyChangeListener(listener);
   }
}

If a setXYZ(..)-method is not found, you should firstly check the spelling of the property-constants (here: PROP_XXXXX). This one must be written exactly as the get and set-methods. Merely the get and set is left out and the first letter is written small.
Example:
there would be the method getValue() and setValue(), so the constant had to be defined as „value“.
Example:

public static final String PROP_VALUE = "value";

Secondly, you can set a breakpoint in the method ValueBinding#doUpdate(..) (e.g. at the call of the method updateValueStrategy.doSet(..)) to find the bug.
Careful! In Eclipse 3.3 there is a bug: The propertymethod/ property-constant is not allowed to begin with two capital letters (so, not: getVAlue() with „vAlue“)!!