001// Copyright 2004, 2005 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry.wml;
016
017import org.apache.tapestry.IMarkupWriter;
018import org.apache.tapestry.IRequestCycle;
019import org.apache.tapestry.form.AbstractFormComponent;
020
021/**
022 * A base class for building components that correspond to WML postfield elements. All such
023 * components must be wrapped (directly or indirectly) by a {@link Go}component.
024 * 
025 * @author David Solis
026 * @since 3.0
027 */
028
029public abstract class AbstractPostfield extends AbstractFormComponent
030{
031    /**
032     * @see org.apache.tapestry.form.AbstractFormComponent#renderFormComponent(org.apache.tapestry.IMarkupWriter, org.apache.tapestry.IRequestCycle)
033     */
034    protected void renderFormComponent(IMarkupWriter writer, IRequestCycle cycle)
035    {
036        writer.beginEmpty("postfield");
037
038        writer.attribute("name", getName());
039
040        String varName = getVarName();
041        writer.attributeRaw("value", varName != null ? getEncodedVarName(varName) : "");
042
043        renderInformalParameters(writer, cycle);
044
045        writer.closeTag();
046    }
047
048    private String getEncodedVarName(String varName)
049    {
050        return "$(" + varName + ")";
051    }
052
053    public boolean isDisabled()
054    {
055        return false;
056    }
057
058    public abstract String getVarName();
059
060    public void updateValue(Object value)
061    {
062        getBinding("value").setObject(value);
063    }
064}