org.apache.wicket.markup.html.form.IChoiceRenderer.java Source code

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Here is the source code for org.apache.wicket.markup.html.form.IChoiceRenderer.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.wicket.markup.html.form;

import java.util.List;

import org.apache.wicket.model.IDetachable;
import org.apache.wicket.model.IModel;

/**
 * Renders one choice. Separates the 'id' values used for internal representation from 'display
 * values' which are the values shown to the user of components that use this renderer.
 *
 * @author jcompagner
 *
 * @param <T>
 *            The model object type
 */
public interface IChoiceRenderer<T> extends IDetachable {
    /**
     * Get the value for displaying to an end user.
     *
     * @param object
     *            the actual object
     * @return the value meant for displaying to an end user
     */
    Object getDisplayValue(T object);

    /**
     * This method is called to get the id value of an object (used as the value attribute of a
     * choice element) The id can be extracted from the object like a primary key, or if the list is
     * stable you could just return a toString of the index.
     * <p>
     * Note that the given index can be {@code -1} if the object in question is not contained in the
     * available choices.
     *
     * @param object
     *            The object for which the id should be generated
     * @param index
     *            The index of the object in the choices list.
     * @return String
     */
    String getIdValue(T object, int index);

    /**
     * This method is called to get an object back from its id representation.
     *
     * The {@code id} may be used to find/load the object in a more efficient way
     * than loading all {@code choices} and find the one with the same id in the list
     *
     * @param id
     *          The id representation of the object
     * @param choices
     *          The list of all rendered choices
     * @return A choice from the list that has this {@code id}
     */
    T getObject(String id, IModel<? extends List<? extends T>> choices);

    /**
     * Override when needed.
     */
    @Override
    default void detach() {
    }

}