/*
 * Copyright 2014-2020 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.data.jpa.repository;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.data.jpa.repository.query.JpaQueryMethod;

Annotation to configure the JPA 2.1 EntityGraphs that should be used on repository methods. Since 1.9 we support the definition of dynamic EntityGraphs by allowing to customize the fetch-graph via attributePaths() ad-hoc fetch-graph configuration. If attributePaths() are specified then we ignore the entity-graph name value() and treat this EntityGraph as dynamic. 
Author:
Christoph Strobl, Thomas Darimont, Oerd Cukalla
Since:
1.6/**
 * Annotation to configure the JPA 2.1 {@link javax.persistence.EntityGraph}s that should be used on repository methods.
 * Since 1.9 we support the definition of dynamic {@link EntityGraph}s by allowing to customize the fetch-graph via
 * {@link #attributePaths()} ad-hoc fetch-graph configuration.
 * 
 * If {@link #attributePaths()} are specified then we ignore the entity-graph name {@link #value()} and treat this 
 * {@link EntityGraph} as dynamic.
 *
 * @author Christoph Strobl
 * @author Thomas Darimont
 * @author Oerd Cukalla
 * @since 1.6
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
@Documented
public @interface EntityGraph {

	
The name of the EntityGraph to use. If empty we fall-back to JpaQueryMethod.getNamedQueryName() as the value. 
Returns:
/**
	 * The name of the EntityGraph to use. If empty we fall-back to {@link JpaQueryMethod#getNamedQueryName()} as the
	 * value.
	 *
	 * @return
	 */
	String value() default "";

	
The EntityGraphType of the EntityGraph to use, defaults to EntityGraphType.FETCH. 
Returns:
/**
	 * The {@link EntityGraphType} of the EntityGraph to use, defaults to {@link EntityGraphType#FETCH}.
	 *
	 * @return
	 */
	EntityGraphType type() default EntityGraphType.FETCH;

	
The paths of attributes of this EntityGraph to use, empty by default. You can refer to direct properties of the entity or nested properties via a property.nestedProperty. 
Returns:
Since:
1.9/**
	 * The paths of attributes of this {@link EntityGraph} to use, empty by default. You can refer to direct properties of
	 * the entity or nested properties via a {@code property.nestedProperty}.
	 *
	 * @return
	 * @since 1.9
	 */
	String[] attributePaths() default {};

	
Enum for JPA 2.1 EntityGraph types. 
Author:
Thomas Darimont
Since:
1.6/**
	 * Enum for JPA 2.1 {@link javax.persistence.EntityGraph} types.
	 *
	 * @author Thomas Darimont
	 * @since 1.6
	 */
	public enum EntityGraphType {

		
When the javax.persistence.loadgraph property is used to specify an entity graph, attributes that are specified
by attribute nodes of the entity graph are treated as FetchType.EAGER and attributes that are not specified are
treated according to their specified or default FetchType.
See Also:
JPA 2.1
		 *      Specification: 3.7.4.2 Load Graph Semantics/**
		 * When the javax.persistence.loadgraph property is used to specify an entity graph, attributes that are specified
		 * by attribute nodes of the entity graph are treated as FetchType.EAGER and attributes that are not specified are
		 * treated according to their specified or default FetchType.
		 *
		 * @see <a href="https://download.oracle.com/otn-pub/jcp/persistence-2_1-fr-eval-spec/JavaPersistence.pdf">JPA 2.1
		 *      Specification: 3.7.4.2 Load Graph Semantics</a>
		 */
		LOAD("javax.persistence.loadgraph"),

		
When the javax.persistence.fetchgraph property is used to specify an entity graph, attributes that are specified
by attribute nodes of the entity graph are treated as FetchType.EAGER and attributes that are not specified are
treated as FetchType.LAZY
See Also:
JPA 2.1
		 *      Specification: 3.7.4.1 Fetch Graph Semantics/**
		 * When the javax.persistence.fetchgraph property is used to specify an entity graph, attributes that are specified
		 * by attribute nodes of the entity graph are treated as FetchType.EAGER and attributes that are not specified are
		 * treated as FetchType.LAZY
		 *
		 * @see <a href="https://download.oracle.com/otn-pub/jcp/persistence-2_1-fr-eval-spec/JavaPersistence.pdf">JPA 2.1
		 *      Specification: 3.7.4.1 Fetch Graph Semantics</a>
		 */
		FETCH("javax.persistence.fetchgraph");

		private final String key;

		private EntityGraphType(String value) {
			this.key = value;
		}

		public String getKey() {
			return key;
		}
	}
}