Programmatically removing all entities from a view object

Recently I had a case where I needed to remove all rows from a view object and found that there was no existing method to do this.
The case for doing such an action is where there is a Master-Detail relationship and the detail relation is used only of there is a certain condition met in the master. If the condition is met then the detail is required, however if the user changes their mind then we need a way of removing any records that may have been created in the detail.

By adding the following method in the View Object Implementation class we can safely delete all records in the view object:

    public void removeAllRows(){
       // rangeSize is -1    
       Row[] rows = getAllRowsInRange();
          for (int r = 0; r < rows.length; r++)
            if (rows[r] != null)
                rows[r].remove();
        
    }

How to reduce coding by extending Managed Beans

After coding many backing/managed beans it became clear to me that there were a few things that I seem to be doing over and over, these were:

• Getting values from the binding layer
• Setting values in the binding layer
• Executing operation bindings
• Using a combination of the above in a backing bean method

The logical thing to do was be to but my code for doing this into a class and extend this class for all of my managed beans. The class is called JSFBean and uses the binding "#{bindings}" to access the binding container. The three methods in the class (so far) are: execute, getValue and setValue.

The bean which I have called JSFBean includes these three methods and some basic error handling. When creating a backing bean simply add "extends JSFBean" to the class definition.

JSFBean.java:

package com.delexian.ui.backing;

import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import oracle.adf.model.binding.DCBindingContainer;
import oracle.binding.OperationBinding;

public class JSFBean {

    public JSFBean() {
    }

    public DCBindingContainer getBindings() {
        FacesContext fc = FacesContext.getCurrentInstance();
        ValueBinding vb = fc.getApplication().createValueBinding("#{bindings}");
        DCBindingContainer dc = (DCBindingContainer) vb.getValue(fc);
 
        return dc;
    }

    public boolean execute(String operation){
        DCBindingContainer bindings = getBindings();
        OperationBinding operationBinding = bindings.getOperationBinding(operation);
        if (operationBinding == null){
            FacesContext fc = FacesContext.getCurrentInstance();
            fc.addMessage("Invalid Operation", new FacesMessage(operation + " is not a valid operation for this page"));
            return true;    
        }
 
        operationBinding.execute();
 
        return operationBinding.getErrors().isEmpty();
    }

    public Object getValue(String el){
             FacesContext fc = FacesContext.getCurrentInstance();
             ValueBinding expr = fc.getApplication().createValueBinding(el);
             return expr.getValue(fc);
         }
  
    public void setValue(String el, Object value){
        FacesContext fc = FacesContext.getCurrentInstance();
        ValueBinding expr = fc.getApplication().createValueBinding(el);
        expr.setValue(fc, value);
 
    }

}

An example usage in a backing bean Employees.java, extends JSFBean:

package com.delexian.ui.backing;

public class Employees extends JSFBean {
    public Employees() {
    }

    public String calculate_action() {
        execute("CalculateCommission");
        execute("Commit");
        return null;
    }
}