com.servoy.j2db.server.headlessclient.dataui.ComponentValueComparator.java Source code

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Here is the source code for com.servoy.j2db.server.headlessclient.dataui.ComponentValueComparator.java

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/*
 This file belongs to the Servoy development and deployment environment, Copyright (C) 1997-2010 Servoy BV
    
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU Affero General Public License as published by the Free
 Software Foundation; either version 3 of the License, or (at your option) any
 later version.
    
 This program is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
    
 You should have received a copy of the GNU Affero General Public License along
 with this program; if not, see http://www.gnu.org/licenses or write to the Free
 Software Foundation,Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
 */
package com.servoy.j2db.server.headlessclient.dataui;

import org.apache.wicket.Component;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.IModelComparator;

import com.servoy.j2db.dataprocessing.IDisplayData;
import com.servoy.j2db.util.Utils;

/**
 * This {@link IModelComparator} will only compare if the components value 
 * then it got from the browser is valid and then tries to compare it with the last rendered value if possible else just the model object.
 * 
 * This makes sure that only user changes compared to the last rendered value are seen as changes.
 * 
 * @author jcompagner
 * 
 */
public class ComponentValueComparator implements IModelComparator {
    private static final long serialVersionUID = 1L;

    public static final IModelComparator COMPARATOR = new ComponentValueComparator();

    /**
     * @see wicket.model.IModelComparator#compare(wicket.Component, java.lang.Object)
     */
    public boolean compare(Component component, Object newObject) {
        // When value is not valid re-setting the original value should be accepted
        if (component instanceof IDisplayData && !((IDisplayData) component).isValueValid()) {
            return false;
        }
        Object previous = null;
        IModel model = component.getInnermostModel();
        if (model instanceof RecordItemModel) {
            previous = ((RecordItemModel) model).getLastRenderedValue(component);
        } else {
            previous = model.getObject();
        }
        // if it is from "" to null or null to "" the value is the same and not overwritten.
        if (previous == null && "".equals(newObject) || "".equals(previous) && newObject == null) //$NON-NLS-1$//$NON-NLS-2$
            return true;
        return Utils.equalObjects(previous, newObject);
    }

}