001    // Copyright 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.form.validator;
016    
017    import java.util.Collection;
018    
019    import org.apache.tapestry.IMarkupWriter;
020    import org.apache.tapestry.IRequestCycle;
021    import org.apache.tapestry.TapestryUtils;
022    import org.apache.tapestry.form.FormComponentContributorContext;
023    import org.apache.tapestry.form.IFormComponent;
024    import org.apache.tapestry.form.ValidationMessages;
025    import org.apache.tapestry.multipart.UploadPart;
026    import org.apache.tapestry.valid.ValidationConstants;
027    import org.apache.tapestry.valid.ValidationConstraint;
028    import org.apache.tapestry.valid.ValidationStrings;
029    import org.apache.tapestry.valid.ValidatorException;
030    
031    /**
032     * {@link org.apache.tapestry.form.validator.Validator} that ensures a value was supplied.
033     * 
034     * @author Howard Lewis Ship
035     * @since 4.0
036     */
037    public class Required extends BaseValidator
038    {
039        public Required()
040        {
041        }
042    
043        public Required(String initializer)
044        {
045            super(initializer);
046        }
047    
048        public boolean getAcceptsNull()
049        {
050            return true;
051        }
052    
053        public void validate(IFormComponent field, ValidationMessages messages, Object object)
054                throws ValidatorException
055        {
056            if ((object == null)
057                    || (String.class.isInstance(object) && (((String) object).length() == 0))
058                    || (Collection.class.isInstance(object) && ((Collection) object).isEmpty())
059                    || (UploadPart.class.isInstance(object) && ((UploadPart) object).getSize() < 1))
060            {
061                String message = buildMessage(messages, field);
062                throw new ValidatorException(message, ValidationConstraint.REQUIRED);
063            }
064        }
065    
066        private String buildMessage(ValidationMessages messages, IFormComponent field)
067        {
068            return messages.formatValidationMessage(
069                    getMessage(),
070                    ValidationStrings.REQUIRED_FIELD,
071                    new Object[]
072                    { field.getDisplayName() });
073        }
074    
075        public void renderContribution(IMarkupWriter writer, IRequestCycle cycle,
076                FormComponentContributorContext context, IFormComponent field)
077        {
078            context.registerForFocus(ValidationConstants.REQUIRED_FIELD);
079    
080            StringBuffer buffer = new StringBuffer("function(event) { Tapestry.require_field(event, '");
081            buffer.append(field.getClientId());
082            buffer.append("', ");
083            buffer.append(TapestryUtils.enquote(buildMessage(context, field)));
084            buffer.append("); }");
085    
086            context.addSubmitHandler(buffer.toString());
087        }
088    
089        /**
090         * Returns true, that's what Required means!
091         */
092        public boolean isRequired()
093        {
094            return true;
095        }
096    }