Fix #1302 n+1 queries in owners

build.gradle

@@ -1,8 +1,8 @@
 plugins {
-  id 'java'
-  id 'org.springframework.boot' version '3.1.1'
-  id 'io.spring.dependency-management' version '1.1.0'
-  id 'org.graalvm.buildtools.native' version '0.9.23'
+    id 'java'
+    id 'org.springframework.boot' version '3.1.1'
+    id 'io.spring.dependency-management' version '1.1.0'
+    id 'org.graalvm.buildtools.native' version '0.9.23'
 }
 
 apply plugin: 'java'
@@ -12,35 +12,35 @@ version = '3.1.0'
 sourceCompatibility = '17'
 
 repositories {
-  mavenCentral()
+    mavenCentral()
 }
 
 ext.webjarsFontawesomeVersion = "4.7.0"
 ext.webjarsBootstrapVersion = "5.2.3"
 
 dependencies {
-  implementation 'org.springframework.boot:spring-boot-starter-cache'
-  implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
-  implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
-  implementation 'org.springframework.boot:spring-boot-starter-web'
-  implementation 'org.springframework.boot:spring-boot-starter-validation'
-  implementation 'javax.cache:cache-api'
-  implementation 'jakarta.xml.bind:jakarta.xml.bind-api'
-  runtimeOnly 'org.springframework.boot:spring-boot-starter-actuator'
-  runtimeOnly "org.webjars.npm:bootstrap:${webjarsBootstrapVersion}"
-  runtimeOnly "org.webjars.npm:font-awesome:${webjarsFontawesomeVersion}"
-  runtimeOnly 'com.github.ben-manes.caffeine:caffeine'
-  runtimeOnly 'com.h2database:h2'
-  runtimeOnly 'com.mysql:mysql-connector-j'
-  runtimeOnly 'org.postgresql:postgresql'
-  developmentOnly 'org.springframework.boot:spring-boot-devtools'
-  testImplementation 'org.springframework.boot:spring-boot-starter-test'
-  testImplementation 'org.springframework.boot:spring-boot-testcontainers'
-  testImplementation 'org.springframework.boot:spring-boot-docker-compose'
-  testImplementation 'org.testcontainers:junit-jupiter'
-  testImplementation 'org.testcontainers:mysql'
+    implementation 'org.springframework.boot:spring-boot-starter-cache'
+    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
+    implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
+    implementation 'org.springframework.boot:spring-boot-starter-web'
+    implementation 'org.springframework.boot:spring-boot-starter-validation'
+    implementation 'javax.cache:cache-api'
+    implementation 'jakarta.xml.bind:jakarta.xml.bind-api'
+    runtimeOnly 'org.springframework.boot:spring-boot-starter-actuator'
+    runtimeOnly "org.webjars.npm:bootstrap:${webjarsBootstrapVersion}"
+    runtimeOnly "org.webjars.npm:font-awesome:${webjarsFontawesomeVersion}"
+    runtimeOnly 'com.github.ben-manes.caffeine:caffeine'
+    runtimeOnly 'com.h2database:h2'
+    runtimeOnly 'com.mysql:mysql-connector-j'
+    runtimeOnly 'org.postgresql:postgresql'
+    developmentOnly 'org.springframework.boot:spring-boot-devtools'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+    testImplementation 'org.springframework.boot:spring-boot-testcontainers'
+    testImplementation 'org.springframework.boot:spring-boot-docker-compose'
+    testImplementation 'org.testcontainers:junit-jupiter'
+    testImplementation 'org.testcontainers:mysql'
 }
 
 tasks.named('test') {
-  useJUnitPlatform()
+    useJUnitPlatform()
 }

src/main/java/org/springframework/samples/petclinic/owner/OwnerController.java

@@ -19,6 +19,7 @@
 import java.util.Map;
 
 import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageImpl;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
 import org.springframework.stereotype.Controller;
@@ -34,6 +35,7 @@
 import org.springframework.web.servlet.ModelAndView;
 
 import jakarta.validation.Valid;
+import org.thymeleaf.util.StringUtils;
 
 /**
  * @author Juergen Hoeller
@@ -89,7 +91,17 @@ public String processFindForm(@RequestParam(defaultValue = "1") int page, Owner
 			Model model) {
 		// allow parameterless GET request for /owners to return all records
 		if (owner.getLastName() == null) {
-			owner.setLastName(""); // empty string signifies broadest possible search
+			List<Owner> ownerList = owners.findAllWithPetsAndVisits();
+			model.addAttribute("owners", ownerList);
+
+			return "owners/ownersList";
+		}
+
+		// empty owner search for all records without n+1 queries
+		if (StringUtils.isEmpty(owner.getLastName())) {
+			List<Owner> ownerList = owners.findAllWithPetsAndVisits();
+			Page<Owner> ownerPageNP1 = new PageImpl<>(ownerList);
+			return addPaginationModel(0, model, ownerPageNP1);
 		}
 
 		// find owners by last name
@@ -112,11 +124,10 @@ public String processFindForm(@RequestParam(defaultValue = "1") int page, Owner
 
 	private String addPaginationModel(int page, Model model, Page<Owner> paginated) {
 		model.addAttribute("listOwners", paginated);
-		List<Owner> listOwners = paginated.getContent();
 		model.addAttribute("currentPage", page);
 		model.addAttribute("totalPages", paginated.getTotalPages());
 		model.addAttribute("totalItems", paginated.getTotalElements());
-		model.addAttribute("listOwners", listOwners);
+		model.addAttribute("listOwners", paginated);
 		return "owners/ownersList";
 	}
 

src/main/java/org/springframework/samples/petclinic/owner/OwnerRepository.java

@@ -57,6 +57,13 @@ public interface OwnerRepository extends Repository<Owner, Integer> {
 	@Transactional(readOnly = true)
 	Page<Owner> findByLastName(@Param("lastName") String lastName, Pageable pageable);
 
+	/**
+	 * Retrieve {@link Owner}s all owners including their pets and visitations
+	 * @return a Collection of {@link Owner}s
+	 */
+	@Query("SELECT DISTINCT owner FROM Owner owner LEFT JOIN FETCH owner.pets LEFT JOIN FETCH pets.visits")
+	List<Owner> findAllWithPetsAndVisits();
+
 	/**
 	 * Retrieve an {@link Owner} from the data store by id.
 	 * @param id the id to search for