| // Copyright 2006, 2007, 2008 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry; |
| |
| /** |
| * Responsible for validation of a single field. |
| * |
| * @param <T> |
| * @see Validator |
| * @see org.apache.tapestry.services.FieldValidatorDefaultSource |
| */ |
| public interface FieldValidator<T> |
| { |
| /** |
| * Invoked after the client-submitted value has been {@link Translator translated} to check that the value conforms |
| * to expectations (often, in terms of minimum or maximum value). If and only if the value is approved by all |
| * Validators is the value applied by the field. |
| * |
| * @param value the translated value supplied by the user |
| * @throws ValidationException if the value violates the constraint |
| */ |
| void validate(T value) throws ValidationException; |
| |
| /** |
| * Invokes {@link Validator#render(Field, Object, org.apache.tapestry.ioc.MessageFormatter, MarkupWriter, |
| * org.apache.tapestry.services.FormSupport)}. This is called at a point "inside" the tag, so that additional |
| * attributes may be added. In many cases, the underlying {@link org.apache.tapestry.Validator} may write |
| * client-side JavaScript to enforce the constraint as well. |
| * |
| * @param writer markup writer to direct output to. |
| * @see org.apache.tapestry.MarkupWriter#attributes(Object[]) |
| */ |
| void render(MarkupWriter writer); |
| |
| /** |
| * Returns true if any underlying {@link org.apache.tapestry.Validator} returns true from {@link |
| * org.apache.tapestry.Validator#isRequired()}. |
| * |
| * @return true if the field is required (a non-blank value is expected) |
| */ |
| boolean isRequired(); |
| } |