001 // Copyright 2004, 2005 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.tapestry.valid; 016 017 import org.apache.tapestry.AbstractComponent; 018 import org.apache.tapestry.BindingException; 019 import org.apache.tapestry.IForm; 020 import org.apache.tapestry.IMarkupWriter; 021 import org.apache.tapestry.IRequestCycle; 022 import org.apache.tapestry.Tapestry; 023 import org.apache.tapestry.TapestryUtils; 024 import org.apache.tapestry.form.IFormComponent; 025 026 /** 027 * Used to label an {@link IFormComponent}. Because such fields know their displayName 028 * (user-presentable name), there's no reason to hard code the label in a page's HTML template (this 029 * also helps with localization). [ <a 030 * href="../../../../../ComponentReference/FieldLabel.html">Component Reference </a>] 031 * 032 * @author Howard Lewis Lewis Ship 033 */ 034 035 public abstract class FieldLabel extends AbstractComponent 036 { 037 // Parameter 038 public abstract boolean isPrerender(); 039 040 /** 041 * Gets the {@link IForm} and {@link IValidationDelegate delegate}, then renders the 042 * label obtained from the field. Does nothing when rewinding. 043 */ 044 045 protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) 046 { 047 IForm form = TapestryUtils.getForm(cycle, this); 048 049 IFormComponent field = getField(); 050 051 if (field != null && isPrerender()) 052 form.prerenderField(writer, field, getLocation()); 053 054 if (cycle.isRewinding()) 055 return; 056 057 String displayName = getDisplayName(); 058 059 if (displayName == null) 060 { 061 if (field == null) 062 throw Tapestry.createRequiredParameterException(this, "field"); 063 064 displayName = field.getDisplayName(); 065 066 if (displayName == null) 067 throw new BindingException(ValidMessages.noDisplayName(this, field), this, null, 068 getBinding("field"), null); 069 } 070 071 IValidationDelegate delegate = form.getDelegate(); 072 073 String id = field == null ? null : field.getClientId(); 074 075 delegate.writeLabelPrefix(field, writer, cycle); 076 077 writer.begin("label"); 078 079 if (id != null) 080 writer.attribute("for", id); 081 082 delegate.writeLabelAttributes(writer, cycle, field); 083 renderInformalParameters(writer, cycle); 084 085 writer.print(displayName, getRaw()); 086 087 writer.end(); 088 089 delegate.writeLabelSuffix(field, writer, cycle); 090 } 091 092 /** displayName parameter */ 093 public abstract String getDisplayName(); 094 095 /** field parameter */ 096 public abstract IFormComponent getField(); 097 098 /** raw parameter */ 099 public abstract boolean getRaw(); 100 }