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
015package org.apache.tapestry.form;
016
017import org.apache.tapestry.IMarkupWriter;
018import org.apache.tapestry.IRequestCycle;
019import org.apache.tapestry.valid.ValidatorException;
020
021/**
022 * Implements the logic used by {@link RequiredField}s for required field checking on rewind and
023 * generating client-side logic during render.
024 * 
025 * @author Paul Ferraro
026 * @since 4.0
027 */
028public interface ValidatableFieldSupport
029{
030    /**
031     * Called during render of the specified component. Renders any contributions from validators.
032     */
033    public void renderContributions(ValidatableField field, IMarkupWriter writer,
034            IRequestCycle cycle);
035
036    /**
037     * Called during rewind of the specified component. Specified value is validated using the 
038     * component's validators.
039     * 
040     * @throws ValidatorException if validation fails
041     */
042    public void validate(ValidatableField component, IMarkupWriter writer, IRequestCycle cycle, Object value) throws ValidatorException;
043
044    /**
045     * Returns true if this component is required. This usually entails a search of the component's
046     * validators.
047     */
048    public boolean isRequired(ValidatableField field);
049}