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 015package org.apache.tapestry5.corelib.components; 016 017import org.apache.tapestry5.CSSClassConstants; 018import org.apache.tapestry5.MarkupWriter; 019import org.apache.tapestry5.ValidationTracker; 020import org.apache.tapestry5.annotations.Environmental; 021import org.apache.tapestry5.annotations.Parameter; 022import org.apache.tapestry5.corelib.internal.InternalMessages; 023import org.apache.tapestry5.services.FormSupport; 024 025import 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 */ 037public 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}