CountLabel.java

/**
 * Copyright 2012 55 Minutes (http://www.55minutes.com)
 *
 * 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 fr.openwide.core.wicket.markup.html.basic;

import org.apache.wicket.markup.html.basic.Label;
import org.apache.wicket.model.IModel;

import fr.openwide.core.wicket.markup.html.model.CountMessageModel;

/**
 * Displays a label with up to three different variations based on whether a
 * numeric model is zero, one, or greater than one. This is incredibly useful
 * for printing count messages where the phrasing needs to change according to
 * singular and plural rules, like this:
 * <ul>
 * <li>There are no friends in your network.</li>
 * <li>There is <u>one friend</u> in your network.</li>
 * <li>There are <u>5 friends</u> in your network.</li>
 * </ul>
 * <p>
 * This class is a simple Label wrapper around a CountMessageModel, which does
 * most of the work. Refer to the class documentation of
 * {@link CountMessageModel} for more details.
 * 
 * @since 2.0
 */
public class CountLabel extends Label {
	private static final long serialVersionUID = -889821092752173878L;

	private boolean hideIfZeroOrNull = false;

	private IModel<? extends Number> countModel;

	/**
	 * Constructs a label that will a display zero, singular or plural variation
	 * based on the value of the specified {@code count} model.
	 * 
	 * @param id
	 *            The wicket:id of the label component. This is will also be
	 *            used as the message key to look up the message strings in the
	 *            localized properties file.
	 * 
	 * @param count
	 *            A number that will be used to choose either the
	 *            <code>id.zero</code>, <code>id.one</code> or
	 *            <code>id.many</code> string from the properties file. It will
	 *            also be made available to the string as an interpolated
	 *            <code>${count}</code> variable.
	 */
	public CountLabel(String id, String messageKey, IModel<? extends Number> countModel) {
		super(id, new CountMessageModel(messageKey, countModel));
		this.countModel = countModel;
		setEscapeModelStrings(false);
	}

	@Override
	protected void onConfigure() {
		super.onConfigure();
		Number count = getCountModelObject();
		setVisible(!hideIfZeroOrNull || (count != null && !(count.longValue() == 0L))); // .equals(0L) will not work for Integers.
	}

	public CountLabel hideIfZeroOrNull() {
		this.hideIfZeroOrNull = true;
		return this;
	}

	private Number getCountModelObject() {
		return countModel != null ? countModel.getObject() : null;
	}

	@Override
	protected void onDetach() {
		super.onDetach();
		if (countModel != null) {
			countModel.detach();
		}
	}

}