PropertyValue.java

/*******************************************************************************
 * Copyright (c) 2011-2016 Medevit OG, Medelexis AG
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Marco Descher, initial API and implementaion
 *     Lucia Amman, bug fixes and improvements
 * Sponsors: M. + P. Richter
 *******************************************************************************/
package at.medevit.elexis.gdt.ui.table.util;

import java.beans.PropertyDescriptor;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.internal.databinding.beans.BeanPropertyHelper;

/**
 * PropertyValue: Resolves nested property Strings like "company.country.name".
 * 
 * Use like this:
 * 
 * <pre>
 * PropertyValue prop = new PropertyValue("country.name");
 * Object countryName = prop.getValue(someObject);
 * </pre>
 * 
 * This class allows to use JFace Data Binding property support to get and set nested property
 * values without observing them.
 * 
 * Please note that this class is not prepared for a case where the classes of the objects change on
 * the path to the property. For example, if you use "country.name" on a "Company" object once, it
 * expects a "Company" object you use it the next time.
 * 
 * WARNING: This uses internal data binding classes. This enhancement described in
 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=285307 would allow to use official API instead of
 * this class.
 * 
 * @author Ralf Ebert <info@ralfebert.de>
 */
@SuppressWarnings("restriction")
public class PropertyValue implements IValue {
	
	private final Object[] properties;
	
	/**
	 * Creates a PropertyValue to access the bean property referred by propertyName.
	 */
	public PropertyValue(String propertyName){
		properties = split(propertyName);
		
	}
	
	private static Object[] split(String propertyName){
		if (propertyName.indexOf('.') == -1)
			return new Object[] {
				propertyName
			};
		List<String> propertyNames = new ArrayList<String>();
		int index;
		while ((index = propertyName.indexOf('.')) != -1) {
			propertyNames.add(propertyName.substring(0, index));
			propertyName = propertyName.substring(index + 1);
		}
		propertyNames.add(propertyName);
		return propertyNames.toArray(new Object[propertyNames.size()]);
	}
	
	/**
	 * Returns the property value referred by object."propertyName"
	 */
	public Object getValue(Object object){
		Object currentObject = object;
		for (int i = 0; i < properties.length; i++) {
			if (currentObject == null)
				return null;
			
			if (properties[i] instanceof String) {
				properties[i] =
					BeanPropertyHelper.getPropertyDescriptor(currentObject.getClass(),
						(String) properties[i]);
			}
			
			if (properties[i] instanceof PropertyDescriptor) {
				currentObject =
					BeanPropertyHelper.readProperty(currentObject,
						(PropertyDescriptor) properties[i]);
			} else {
				throw new RuntimeException("Invalid property: " + properties[i]);
			}
			
		}
		
		return currentObject;
	}
	
	/**
	 * Sets the property value referred by object."propertyName" to value
	 */
	public void setValue(Object object, Object value){
		Object currentObject = object;
		for (int i = 0; i < properties.length; i++) {
			if (currentObject == null)
				throw new RuntimeException(
					"Value cannot be set because of null value in nested property!");
			
			if (properties[i] instanceof String) {
				properties[i] =
					BeanPropertyHelper.getPropertyDescriptor(currentObject.getClass(),
						(String) properties[i]);
			}
			
			if (properties[i] instanceof PropertyDescriptor) {
				boolean lastProperty = (i == properties.length - 1);
				if (lastProperty)
					BeanPropertyHelper.writeProperty(currentObject,
						(PropertyDescriptor) properties[i], value);
				else
					currentObject =
						BeanPropertyHelper.readProperty(currentObject,
							(PropertyDescriptor) properties[i]);
			} else {
				throw new RuntimeException("Invalid property: " + properties[i]);
			}
			
		}
	}
}