framework/src/net/sf/tapestry/valid/FieldLabel.java

/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 The Apache Software Foundation.  All rights
 *  reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution,
 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Apache" and "Apache Software Foundation" and
 *  "Apache Tapestry" must not be used to endorse or promote products
 *  derived from this software without prior written permission. For
 *  written permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache",
 *  "Apache Tapestry", nor may "Apache" appear in their name, without
 *  prior written permission of the Apache Software Foundation.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
 *  <http://www.apache.org/>.
 */
package net.sf.tapestry.valid;

import net.sf.tapestry.AbstractComponent;
import net.sf.tapestry.IMarkupWriter;
import net.sf.tapestry.IRequestCycle;
import net.sf.tapestry.RequestCycleException;
import net.sf.tapestry.Tapestry;
import net.sf.tapestry.form.Form;
import net.sf.tapestry.form.IFormComponent;

/**
 *  Used to label an {@link IFormComponent}.  Because such fields
 *  know their displayName (user-presentable name), there's no reason
 *  to hard code the label in a page's HTML template (this also helps
 *  with localization).
 *
 *  [<a href="../../../../../ComponentReference/FieldLabel.html">Component Reference</a>]

 *
 *  @author Howard Lewis Lewis Ship
 *  @version $Id$
 * 
 **/

public class FieldLabel extends AbstractComponent
{
    private IFormComponent _field;
    private String _displayName;

    /**
     *  Gets the {@link IField} 
     *  and {@link IValidationDelegate delegate},
     *  then renders the label obtained from the field.  Does nothing
     *  when rewinding.
     *
     **/

    protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
        throws RequestCycleException
    {
        if (cycle.isRewinding())
            return;

        String finalDisplayName = (_displayName != null) ? _displayName : _field.getDisplayName();

        if (finalDisplayName == null)
            throw new RequestCycleException(
                Tapestry.getString("FieldLabel.no-display-name", _field.getExtendedId()),
                this);

        IValidationDelegate delegate = Form.get(cycle).getDelegate();

        delegate.writeLabelPrefix(_field, writer, cycle);

        writer.print(finalDisplayName);

        delegate.writeLabelSuffix(_field, writer, cycle);
    }

    public String getDisplayName()
    {
        return _displayName;
    }

    public void setDisplayName(String displayName)
    {
        _displayName = displayName;
    }

    public IFormComponent getField()
    {
        return _field;
    }

    public void setField(IFormComponent field)
    {
        _field = field;
    }

}