    001    // Copyright 2006, 2007, 2008, 2011 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
    015    package org.apache.tapestry5.corelib.components;
    016
    017    import org.apache.tapestry5.CSSClassConstants;
    018    import org.apache.tapestry5.MarkupWriter;
    019    import org.apache.tapestry5.ValidationTracker;
    020    import org.apache.tapestry5.annotations.Environmental;
    021    import org.apache.tapestry5.annotations.Parameter;
    022    import org.apache.tapestry5.corelib.internal.InternalMessages;
    023    import org.apache.tapestry5.services.FormSupport;
    024
    025    import java.util.List;
    026
    027    /**
    028     * Standard validation error presenter. Must be enclosed by a
    029     * {@link org.apache.tapestry5.corelib.components.Form} component. If errors are present, renders a
    030     * div element around a banner message and around an unnumbered list of
    031     * error messages. Renders nothing if the {@link org.apache.tapestry5.ValidationTracker} shows no
    032     * errors.
    033     *
    034     * @see Form
    035     * @tapestrydoc
    036     */
    037    public class Errors
    038    {
    039        /**
    040         * The banner message displayed above the errors. The default value is "You must correct the
    041         * following errors before
    042         * you may continue.".
    043         */
    044        @Parameter("message:default-banner")
    045        private String banner;
    046
    047        /**
    048         * The CSS class for the div element rendered by the component. The default value is "t-error".
    049         */
    050        @Parameter(name = "class")
    051        private String className = CSSClassConstants.ERROR;
    052
    053        // Allow null so we can generate a better error message if missing
    054        @Environmental(false)
    055        private ValidationTracker tracker;
    056
    057        void beginRender(MarkupWriter writer)
    058        {
    059            if (tracker == null)
    060                throw new RuntimeException(InternalMessages.encloseErrorsInForm());
    061
    062            if (!tracker.getHasErrors())
    063                return;
    064
    065            writer.element("div", "class", className);
    066
    067            // Inner div for the banner text
    068            writer.element("div", "class", "t-banner");
    069            writer.write(banner);
    070            writer.end();
    071
    072            List<String> errors = tracker.getErrors();
    073
    074            if (!errors.isEmpty())
    075            {
    076                // Only write out the <UL> if it will contain <LI> elements. An empty <UL> is not
    077                // valid XHTML.
    078
    079                writer.element("ul");
    080
    081                for (String message : errors)
    082                {
    083                    writer.element("li");
    084                    writer.write(message);
    085                    writer.end();
    086                }
    087
    088                writer.end(); // ul
    089            }
    090
    091            writer.end(); // div
    092
    093        }
    094    }