001// Copyright 2006-2013 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
015package org.apache.tapestry5.corelib.components;
016
017import org.apache.tapestry5.BindingConstants;
018import org.apache.tapestry5.MarkupWriter;
019import org.apache.tapestry5.ValidationTracker;
020import org.apache.tapestry5.annotations.Environmental;
021import org.apache.tapestry5.annotations.Import;
022import org.apache.tapestry5.annotations.Parameter;
023import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
024
025import java.util.List;
026import java.util.Set;
027
028/**
029 * Standard validation error presenter. Must be enclosed by a
030 * {@link org.apache.tapestry5.corelib.components.Form} component. If errors are present, renders a
031 * {@code <div>} element around a banner message and around an unnumbered list of
032 * error messages. Renders nothing if the {@link org.apache.tapestry5.ValidationTracker} shows no
033 * errors.
034 *
035 * @tapestrydoc
036 * @see Form
037 */
038@Import(module = "bootstrap/alert")
039public class Errors
040{
041    /**
042     * The banner message displayed above the errors. The default value is "You must correct the
043     * following errors before
044     * you may continue.".
045     */
046    @Parameter("message:core-default-error-banner")
047    private String banner;
048
049    /**
050     * If true, then only errors global to the form (unassociated with any specific field) are
051     * presented. By default all errors (associated with fields, or not) are presented; with unassoicated
052     * errors presented first.
053     *
054     * @since 5.4
055     */
056    @Parameter
057    private boolean globalOnly;
058
059    /**
060     * The CSS class for the div element rendered by the component.
061     */
062    @Parameter(name = "class", defaultPrefix = BindingConstants.LITERAL, value = "alert alert-danger")
063    private String className;
064
065    // Allow null so we can generate a better error message if missing
066    @Environmental(false)
067    private ValidationTracker tracker;
068
069    boolean beginRender(MarkupWriter writer)
070    {
071        if (tracker == null)
072            throw new RuntimeException("The Errors component must be enclosed by a Form component.");
073
074        if (!tracker.getHasErrors())
075        {
076            return false;
077        }
078
079        List<String> errors =
080                globalOnly ? tracker.getUnassociatedErrors() : tracker.getErrors();
081
082        if (errors.isEmpty())
083        {
084            return false;
085        }
086
087        Set<String> previousErrors = CollectionFactory.newSet();
088
089        writer.element("div", "class", "alert-dismissable " + className);
090        writer.element("button",
091                "type", "button",
092                "class", "close",
093                "data-dismiss", "alert");
094        writer.writeRaw("&times;");
095        writer.end();
096
097        writer.element("h4");
098        writer.writeRaw(banner);
099        writer.end();
100
101        writer.element("ul");
102
103        for (String message : errors)
104        {
105            if (previousErrors.contains(message))
106            {
107                continue;
108            }
109
110            writer.element("li");
111            writer.write(message);
112            writer.end();
113
114            previousErrors.add(message);
115        }
116
117        writer.end(); // ul
118
119        writer.end(); // div
120
121        return false;
122    }
123}