001// Copyright 2008, 2009, 2022 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.annotations;
016
017import java.lang.annotation.Documented;
018import static java.lang.annotation.ElementType.FIELD;
019import java.lang.annotation.Retention;
020import static java.lang.annotation.RetentionPolicy.RUNTIME;
021import java.lang.annotation.Target;
022
023import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.*;
024import org.apache.tapestry5.ioc.annotations.UseWith;
025
026/**
027 * Allows components defined in the template to be injected as read-only properties.
028 */
029@Target(FIELD)
030@Documented
031@Retention(RUNTIME)
032@UseWith({COMPONENT,PAGE})
033public @interface InjectComponent
034{
035    /**
036     * The name of the component to inject. Defaults to the name of the annotated field.
037     */
038    String value() default "";
039
040    /**
041     * If true, allows the component to be missing without throwing an exception.
042     * @since 5.8.2
043     */
044    boolean optional() default false;
045}