eloptionscollectiontag.java

jakarta-struts-1.2.4-src

/*
 * $Header: /home/cvs/jakarta-struts/contrib/struts-el/src/share/org/apache/strutsel/taglib/html/ELOptionsCollectionTag.java,v 1.9 2004/03/14 07:15:01 sraeburn Exp $
 * $Revision: 1.9 $
 * $Date: 2004/03/14 07:15:01 $
 *
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.strutsel.taglib.html;

import org.apache.struts.taglib.html.OptionsCollectionTag;
import javax.servlet.jsp.JspException;
import org.apache.strutsel.taglib.utils.EvalHelper;

/**
 * Tag for creating multiple <select> options from a collection. The
 * collection may be part of the enclosing form, or may be independent of
 * the form. Each element of the collection must expose a 'label' and a
 * 'value', the property names of which are configurable by attributes of
 * this tag.
 * <p>
 * The collection may be an array of objects, a Collection, an Enumeration,
 * an Iterator, or a Map.
 * <p>
 * <b>NOTE</b> - This tag requires a Java2 (JDK 1.2 or later) platform.
 *<p>
 * This class is a subclass of the class
 * <code>org.apache.struts.taglib.html.OptionsCollectionTag</code> which
 * provides most of the described functionality.  This subclass allows all
 * attribute values to be specified as expressions utilizing the JavaServer
 * Pages Standard Library expression language.
 *
 * @version $Revision: 1.9 $
 */
public class ELOptionsCollectionTag extends OptionsCollectionTag {

    /**
     * Instance variable mapped to "filter" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String filterExpr;
    /**
     * Instance variable mapped to "label" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String labelExpr;
    /**
     * Instance variable mapped to "name" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String nameExpr;
    /**
     * Instance variable mapped to "property" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String propertyExpr;
    /**
     * Instance variable mapped to "style" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String styleExpr;
    /**
     * Instance variable mapped to "styleClass" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String styleClassExpr;
    /**
     * Instance variable mapped to "value" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String valueExpr;

    /**
     * Getter method for "filter" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getFilterExpr() { return (filterExpr); }
    /**
     * Getter method for "label" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getLabelExpr() { return (labelExpr); }
    /**
     * Getter method for "name" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getNameExpr() { return (nameExpr); }
    /**
     * Getter method for "property" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getPropertyExpr() { return (propertyExpr); }
    /**
     * Getter method for "style" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getStyleExpr() { return (styleExpr); }
    /**
     * Getter method for "styleClass" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getStyleClassExpr() { return (styleClassExpr); }
    /**
     * Getter method for "value" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getValueExpr() { return (valueExpr); }

    /**
     * Setter method for "filter" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setFilterExpr(String filterExpr) { this.filterExpr = filterExpr; }
    /**
     * Setter method for "label" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setLabelExpr(String labelExpr) { this.labelExpr = labelExpr; }
    /**
     * Setter method for "name" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setNameExpr(String nameExpr) { this.nameExpr = nameExpr; }
    /**
     * Setter method for "property" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setPropertyExpr(String propertyExpr) { this.propertyExpr = propertyExpr; }
    /**
     * Setter method for "style" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setStyleExpr(String styleExpr) { this.styleExpr = styleExpr; }
    /**
     * Setter method for "styleClass" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setStyleClassExpr(String styleClassExpr) { this.styleClassExpr = styleClassExpr; }
    /**
     * Setter method for "value" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setValueExpr(String valueExpr) { this.valueExpr = valueExpr; }

    /**
     * Resets attribute values for tag reuse.
     */
    public void release()
    {
        super.release();
        setFilterExpr(null);
        setLabelExpr(null);
        setNameExpr(null);
        setPropertyExpr(null);
        setStyleExpr(null);
        setStyleClassExpr(null);
        setValueExpr(null);
    }

    /**
     * Process the start tag.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {
        evaluateExpressions();
        return (super.doStartTag());
    }
    
    /**
     * Processes all attribute values which use the JSTL expression evaluation
     * engine to determine their values.
     *
     * @exception JspException if a JSP exception has occurred
     */
    private void evaluateExpressions() throws JspException {
        String  string  = null;
        Boolean bool    = null;

        if ((bool = EvalHelper.evalBoolean("filter", getFilterExpr(),
                                           this, pageContext)) != null)
            setFilter(bool.booleanValue());

        if ((string = EvalHelper.evalString("label", getLabelExpr(),
                                            this, pageContext)) != null)
            setLabel(string);

        if ((string = EvalHelper.evalString("name", getNameExpr(),
                                            this, pageContext)) != null)
            setName(string);

        if ((string = EvalHelper.evalString("property", getPropertyExpr(),
                                            this, pageContext)) != null)
            setProperty(string);

        if ((string = EvalHelper.evalString("style", getStyleExpr(),
                                            this, pageContext)) != null)
            setStyle(string);

        if ((string = EvalHelper.evalString("styleClass", getStyleClassExpr(),
                                            this, pageContext)) != null)
            setStyleClass(string);

        // Note that in contrast to other elements which have "style" and
        // "styleClass" attributes, this tag does not have a "styleId"
        // attribute.  This is because this produces the "id" attribute, which
        // has to be unique document-wide, but this tag can generate more than
        // one "option" element.  Thus, the base tag, "OptionsCollectionTag"
        // does not support this attribute.

        if ((string = EvalHelper.evalString("value", getValueExpr(),
                                            this, pageContext)) != null)
            setValue(string);
    }
}