de.alpharogroup.wicket.components.form.ChoicesListView.java Source code

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Here is the source code for de.alpharogroup.wicket.components.form.ChoicesListView.java

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/**
 * Copyright (C) 2010 Asterios Raptis
 *
 * 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 de.alpharogroup.wicket.components.form;

import java.util.List;

import org.apache.wicket.markup.html.form.IChoiceRenderer;
import org.apache.wicket.markup.html.list.ListView;
import org.apache.wicket.model.IModel;
import org.apache.wicket.util.convert.IConverter;

/**
 * A base ListView that provides conveniences for rendering its items using an IChoiceRenderer.
 * 
 * This class is inspired from fiftyfive.wicket.core project. Some changes with the generic types
 * was done.
 * 
 * @param <T>
 *            the generic type
 */
public abstract class ChoicesListView<T> extends ListView<T> {
    /**
     * The serialVersionUID.
     */
    private static final long serialVersionUID = 1L;

    /** The choice renderer. */
    private final IChoiceRenderer<T> choiceRenderer;

    /**
     * Construct a list view that will expose the specified IChoiceRenderer for rendering its list
     * items.
     * 
     * @param id
     *            the id
     * @param choices
     *            the list of choices
     * @param renderer
     *            the choice renderer
     */
    public ChoicesListView(final String id, final IModel<List<T>> choices, final IChoiceRenderer<T> renderer) {
        super(id, choices);
        this.choiceRenderer = renderer;
    }

    /**
     * Convenience method exposed to subclasses for determining the display value of a given list
     * item. This delegates to {@link IChoiceRenderer#getDisplayValue getDisplayValue()} on the
     * IChoiceRenderer. The display value will be coverted to a String if necessary using Wicket's
     * {@link IConverter} system.
     * 
     * @param choice
     *            The current value of the list that is being rendered.
     * @return the choice label
     */
    @SuppressWarnings({ "unchecked", "rawtypes" })
    protected String getChoiceLabel(final T choice) {
        // This code was copied from Wicket's CheckBoxMultipleChoice.java
        final Object displayValue = getChoiceRenderer().getDisplayValue(choice);
        final Class<?> objectClass = displayValue == null ? null : displayValue.getClass();
        // Get label for choice
        String label = "";
        if ((objectClass != null) && (objectClass != String.class)) {
            final IConverter converter = getConverter(objectClass);
            label = converter.convertToString(displayValue, getLocale());
        } else if (displayValue != null) {
            label = displayValue.toString();
        }
        return label;
    }

    /**
     * Returns the IChoiceRenderer that was passed to the constructor.
     * 
     * @return the choice renderer
     */
    public IChoiceRenderer<T> getChoiceRenderer() {
        return this.choiceRenderer;
    }

    /**
     * Convenience method exposed to subclasses for determining the unique ID of the given list
     * item. This delegates to {@link IChoiceRenderer#getIdValue getIdValue()} on the
     * IChoiceRenderer.
     * 
     * @param choice
     *            The current value of the list that is being rendered.
     * @param index
     *            The zero-indexed position of that value in the list.
     * @return the choice value
     */
    protected String getChoiceValue(final T choice, final int index) {
        return getChoiceRenderer().getIdValue(choice, index);
    }
}