Update data-jpa sample with NamedEntityGraph

Author: christophstrobl

data-jpa/src/aotSmokeTest/java/com/example/data/jpa/DataJpaApplicationAotTests.java

@@ -25,10 +25,10 @@ void insert(AssertableOutput output) {
 	void listAllAuthors(AssertableOutput output) {
 		Awaitility.await().atMost(Duration.ofSeconds(10)).untilAsserted(() -> {
 			assertThat(output).hasSingleLineContaining("listAllAuthors(): author = Author{name='Josh Long'")
-					.hasSingleLineContaining("Book{title='Cloud Native Java'}")
-					.hasSingleLineContaining("Book{title='Reactive Spring'}")
+					.hasSingleLineContaining("Book{title='Cloud Native Java'")
+					.hasSingleLineContaining("Book{title='Reactive Spring'")
 					.hasSingleLineContaining("listAllAuthors(): author = Author{name='Martin Kleppmann'}")
-					.hasSingleLineContaining("Book{title='Designing Data Intensive Applications'}");
+					.hasSingleLineContaining("Book{title='Designing Data Intensive Applications'");
 		});
 	}
 
@@ -70,4 +70,12 @@ void callback(AssertableOutput output) {
 		});
 	}
 
+	@Test
+	void entityGraph(AssertableOutput output) {
+		Awaitility.await().atMost(Duration.ofSeconds(10)).untilAsserted(() -> {
+			assertThat(output).hasSingleLineContaining(
+					"namedEntityGraph: Book{title='Spring in Action', authors=[Author{name='Craig Walls'}]}");
+		});
+	}
+
 }

data-jpa/src/main/java/com/example/data/jpa/BookRepository.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2022 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 com.example.data.jpa;
+
+import com.example.data.jpa.model.Book;
+import org.springframework.data.jpa.repository.EntityGraph;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.ListCrudRepository;
+
+public interface BookRepository extends ListCrudRepository<Book, Long> {
+
+	@EntityGraph(value = "Book.authors")
+	@Query("SELECT b FROM Book b WHERE b.title = :title")
+	Book findByTitleWithNamedGraph(String title);
+
+	@EntityGraph(attributePaths = "authors")
+	@Query("SELECT b FROM Book b WHERE b.title = :title")
+	Book findByTitleWithAdHocGraph(String title);
+
+}

data-jpa/src/main/java/com/example/data/jpa/CLR.java

@@ -1,6 +1,7 @@
 package com.example.data.jpa;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
@@ -16,8 +17,11 @@ class CLR implements CommandLineRunner {
 
 	private final AuthorRepository authorRepository;
 
-	CLR(AuthorRepository authorRepository) {
+	private final BookRepository bookRepository;
+
+	CLR(AuthorRepository authorRepository, BookRepository bookRepository) {
 		this.authorRepository = authorRepository;
+		this.bookRepository = bookRepository;
 	}
 
 	@Override
@@ -29,6 +33,7 @@ public void run(String... args) {
 		findByPartialName();
 		queryFindByName();
 		deleteAll();
+		entityGraph();
 	}
 
 	private void deleteAll() {
@@ -61,6 +66,17 @@ private void findById(List<Author> authors) {
 		System.out.printf("findById(): author2 = %s%n", author2);
 	}
 
+	private void entityGraph() {
+
+		Book book = new Book(null, "Spring in Action");
+		Author author = new Author(null, "Craig Walls", Collections.emptySet());
+		book.getAuthors().add(author);
+		bookRepository.save(book);
+
+		Book loaded = bookRepository.findByTitleWithNamedGraph("Spring in Action");
+		System.out.println("namedEntityGraph: " + loaded);
+	}
+
 	private void listAllAuthors() {
 		List<Author> authors = this.authorRepository.findAll();
 		for (Author author : authors) {

data-jpa/src/main/java/com/example/data/jpa/model/Book.java

@@ -1,12 +1,19 @@
 package com.example.data.jpa.model;
 
+import java.util.HashSet;
 import java.util.Objects;
+import java.util.Set;
 
+import jakarta.persistence.CascadeType;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.Id;
+import jakarta.persistence.NamedAttributeNode;
+import jakarta.persistence.NamedEntityGraph;
+import jakarta.persistence.OneToMany;
 
 @Entity
+@NamedEntityGraph(name = "Book.authors", attributeNodes = @NamedAttributeNode("authors"))
 public class Book {
 
 	@Id
@@ -15,6 +22,9 @@ public class Book {
 
 	private String title;
 
+	@OneToMany(cascade = CascadeType.ALL)
+	private Set<Author> authors = new HashSet<>();
+
 	protected Book() {
 	}
 
@@ -35,6 +45,14 @@ public void setTitle(String title) {
 		this.title = title;
 	}
 
+	public Set<Author> getAuthors() {
+		return authors;
+	}
+
+	public void setAuthors(Set<Author> authors) {
+		this.authors = authors;
+	}
+
 	@Override
 	public boolean equals(Object o) {
 		if (this == o) {
@@ -54,7 +72,7 @@ public int hashCode() {
 
 	@Override
 	public String toString() {
-		return "Book{" + "title='" + title + '\'' + '}';
+		return "Book{" + "title='" + title + '\'' + ", authors=" + authors + '}';
 	}
 
 }