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lor6lor6
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Merge pull request eugenp#5764 from eelhazati/master
BAEL-2395: JPA Entity Graph.
2 parents a6c9c58 + 8d39316 commit eaeed72

8 files changed

Lines changed: 428 additions & 19 deletions

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‎persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entitygraph/MainApp.java‎

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package com.baeldung.jpa.entitygraph;
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import com.baeldung.jpa.entitygraph.model.Post;
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import com.baeldung.jpa.entitygraph.repo.PostRepository;
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public class MainApp {
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public static void main(String... args) {
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Long postId = 1L;
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Post post = null;
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PostRepository postRepository = new PostRepository();
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//Using EntityManager.find().
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post = postRepository.find(postId);
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post = postRepository.findWithEntityGraph(postId);
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post = postRepository.findWithEntityGraph2(postId);
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//Using JPQL: Query and TypedQuery
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post = postRepository.findUsingJpql(postId);
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//Using Criteria API
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post = postRepository.findUsingCriteria(postId);
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postRepository.clean();
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}
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}

‎persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entitygraph/model/Comment.java‎

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package com.baeldung.jpa.entitygraph.model;
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import javax.persistence.*;
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@Entity
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public class Comment {
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@Id
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@GeneratedValue(strategy = GenerationType.IDENTITY)
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private Long id;
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private String reply;
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@ManyToOne(fetch = FetchType.LAZY)
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@JoinColumn
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private Post post;
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@ManyToOne(fetch = FetchType.LAZY)
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@JoinColumn
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private User user;
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//...
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public Comment() {
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}
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public Comment(String reply, Post post, User user) {
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this.reply = reply;
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this.post = post;
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this.user = user;
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}
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public Long getId() {
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return id;
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}
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public void setId(Long id) {
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this.id = id;
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}
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public String getReply() {
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return reply;
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}
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public void setReply(String reply) {
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this.reply = reply;
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}
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public Post getPost() {
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return post;
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}
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public void setPost(Post post) {
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this.post = post;
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}
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public User getUser() {
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return user;
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}
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public void setUser(User user) {
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this.user = user;
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}
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}

‎persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entitygraph/model/Post.java‎

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package com.baeldung.jpa.entitygraph.model;
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import javax.persistence.*;
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import java.io.Serializable;
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import java.util.ArrayList;
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import java.util.List;
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@NamedEntityGraph(
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name = "post-entity-graph",
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attributeNodes = {
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@NamedAttributeNode("subject"),
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@NamedAttributeNode("user"),
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@NamedAttributeNode("comments"),
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}
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)
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@NamedEntityGraph(
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name = "post-entity-graph-with-comment-users",
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attributeNodes = {
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@NamedAttributeNode("subject"),
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@NamedAttributeNode("user"),
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@NamedAttributeNode(value = "comments", subgraph = "comments-subgraph"),
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},
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subgraphs = {
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@NamedSubgraph(
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name = "comments-subgraph",
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attributeNodes = {
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@NamedAttributeNode("user")
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}
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)
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}
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)
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@Entity
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public class Post {
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@Id
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@GeneratedValue(strategy = GenerationType.IDENTITY)
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private Long id;
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private String subject;
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@OneToMany(mappedBy = "post")
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private List<Comment> comments = new ArrayList<>();
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@ManyToOne(fetch = FetchType.LAZY)
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@JoinColumn
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private User user;
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//...
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public Post() {
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}
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public Post(String subject, User user) {
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this.subject = subject;
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this.user = user;
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}
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public Long getId() {
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return id;
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}
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public void setId(Long id) {
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this.id = id;
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}
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public String getSubject() {
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return subject;
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}
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public void setSubject(String subject) {
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this.subject = subject;
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}
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public List<Comment> getComments() {
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return comments;
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}
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public void setComments(List<Comment> comments) {
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this.comments = comments;
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}
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public User getUser() {
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return user;
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}
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public void setUser(User user) {
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this.user = user;
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}
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}

‎persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entitygraph/model/User.java‎

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package com.baeldung.jpa.entitygraph.model;
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import javax.persistence.Entity;
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import javax.persistence.GeneratedValue;
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import javax.persistence.GenerationType;
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import javax.persistence.Id;
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@Entity
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public class User {
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@Id
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@GeneratedValue(strategy = GenerationType.IDENTITY)
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private Long id;
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private String name;
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private String email;
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//...
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public User() {
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}
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public User(String email) {
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this.email = email;
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}
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public Long getId() {
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return id;
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}
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public void setId(Long id) {
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this.id = id;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public String getEmail() {
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return email;
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}
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public void setEmail(String email) {
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this.email = email;
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}
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}

‎persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entitygraph/repo/PostRepository.java‎

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package com.baeldung.jpa.entitygraph.repo;
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import com.baeldung.jpa.entitygraph.model.Post;
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import javax.persistence.*;
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import javax.persistence.criteria.CriteriaBuilder;
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import javax.persistence.criteria.CriteriaQuery;
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import javax.persistence.criteria.Root;
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import java.util.HashMap;
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import java.util.Map;
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public class PostRepository {
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private EntityManagerFactory emf = null;
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public PostRepository() {
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Map properties = new HashMap();
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properties.put("hibernate.show_sql", "true");
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properties.put("hibernate.format_sql", "true");
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emf = Persistence.createEntityManagerFactory("entity-graph-pu", properties);
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}
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public Post find(Long id) {
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EntityManager entityManager = emf.createEntityManager();
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Post post = entityManager.find(Post.class, id);
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entityManager.close();
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return post;
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}
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public Post findWithEntityGraph(Long id) {
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EntityManager entityManager = emf.createEntityManager();
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EntityGraph entityGraph = entityManager.getEntityGraph("post-entity-graph");
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Map<String, Object> properties = new HashMap<>();
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properties.put("javax.persistence.fetchgraph", entityGraph);
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Post post = entityManager.find(Post.class, id, properties);
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entityManager.close();
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return post;
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}
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public Post findWithEntityGraph2(Long id) {
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EntityManager entityManager = emf.createEntityManager();
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EntityGraph<Post> entityGraph = entityManager.createEntityGraph(Post.class);
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entityGraph.addAttributeNodes("subject");
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entityGraph.addAttributeNodes("user");
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entityGraph.addSubgraph("comments")
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.addAttributeNodes("user");
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Map<String, Object> properties = new HashMap<>();
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properties.put("javax.persistence.fetchgraph", entityGraph);
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Post post = entityManager.find(Post.class, id, properties);
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entityManager.close();
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return post;
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}
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public Post findUsingJpql(Long id) {
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EntityManager entityManager = emf.createEntityManager();
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EntityGraph entityGraph = entityManager.getEntityGraph("post-entity-graph-with-comment-users");
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Post post = entityManager.createQuery("Select p from Post p where p.id=:id", Post.class)
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.setParameter("id", id)
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.setHint("javax.persistence.fetchgraph", entityGraph)
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.getSingleResult();
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entityManager.close();
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return post;
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}
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public Post findUsingCriteria(Long id) {
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EntityManager entityManager = emf.createEntityManager();
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EntityGraph entityGraph = entityManager.getEntityGraph("post-entity-graph-with-comment-users");
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CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
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CriteriaQuery<Post> criteriaQuery = criteriaBuilder.createQuery(Post.class);
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Root<Post> root = criteriaQuery.from(Post.class);
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criteriaQuery.where(criteriaBuilder.equal(root.<Long>get("id"), id));
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TypedQuery<Post> typedQuery = entityManager.createQuery(criteriaQuery);
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typedQuery.setHint("javax.persistence.loadgraph", entityGraph);
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Post post = typedQuery.getSingleResult();
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entityManager.close();
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return post;
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}
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public void clean() {
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emf.close();
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}
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}

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