Switch from Postgres to H2

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/Application.java

@@ -0,0 +1,12 @@
+package com.baeldung;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/model/Payment.java

@@ -0,0 +1,55 @@
+package com.baeldung.model;
+
+import javax.persistence.*;
+
+@Entity
+public class Payment {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+
+    private Long amount;
+
+    @Column(unique = true)
+    private String referenceNumber;
+
+    @Enumerated(EnumType.STRING)
+    private State state;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getAmount() {
+        return amount;
+    }
+
+    public void setAmount(Long amount) {
+        this.amount = amount;
+    }
+
+    public String getReferenceNumber() {
+        return referenceNumber;
+    }
+
+    public void setReferenceNumber(String referenceNumber) {
+        this.referenceNumber = referenceNumber;
+    }
+
+    public State getState() {
+        return state;
+    }
+
+    public void setState(State state) {
+        this.state = state;
+    }
+
+    public enum State {
+        STARTED, FAILED, SUCCESSFUL
+    }
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/model/User.java

@@ -0,0 +1,42 @@
+package com.baeldung.model;
+
+import javax.persistence.*;
+import java.util.Set;
+
+@Entity
+@Table(name = "users")
+public class User {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+
+    private String username;
+
+    @ElementCollection
+    private Set<String> permissions;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public Set<String> getPermissions() {
+        return permissions;
+    }
+
+    public void setPermissions(Set<String> permissions) {
+        this.permissions = permissions;
+    }
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/repository/UserRepository.java

@@ -0,0 +1,17 @@
+package com.baeldung.repository;
+
+import com.baeldung.model.User;
+import org.springframework.data.jpa.repository.EntityGraph;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface UserRepository extends JpaRepository<User, Long> {
+
+    @EntityGraph(attributePaths = "permissions")
+    Optional<User> findDetailedByUsername(String username);
+
+    Optional<User> findSummaryByUsername(String username);
+
+    Optional<User> findByUsername(String username);
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/service/SimpleUserService.java

@@ -0,0 +1,24 @@
+package com.baeldung.service;
+
+import com.baeldung.model.User;
+import com.baeldung.repository.UserRepository;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.Optional;
+
+@Service
+public class SimpleUserService implements UserService {
+
+    private final UserRepository userRepository;
+
+    public SimpleUserService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
+    @Override
+    @Transactional(readOnly = true)
+    public Optional<User> findOne(String username) {
+        return userRepository.findDetailedByUsername(username);
+    }
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/service/UserService.java

@@ -0,0 +1,9 @@
+package com.baeldung.service;
+
+import com.baeldung.model.User;
+
+import java.util.Optional;
+
+public interface UserService {
+    Optional<User> findOne(String username);
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/web/DetailedUserDto.java

@@ -0,0 +1,45 @@
+package com.baeldung.web;
+
+import com.baeldung.model.User;
+
+import java.util.Set;
+
+public class DetailedUserDto {
+
+    private Long id;
+    private String username;
+    private Set<String> permissions;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public Set<String> getPermissions() {
+        return permissions;
+    }
+
+    public void setPermissions(Set<String> permissions) {
+        this.permissions = permissions;
+    }
+
+    public static DetailedUserDto fromEntity(User user) {
+        DetailedUserDto detailed = new DetailedUserDto();
+        detailed.setId(user.getId());
+        detailed.setUsername(user.getUsername());
+        detailed.setPermissions(user.getPermissions());
+
+        return detailed;
+    }
+}

persistence-modules/spring-data-jpa-3/src/main/java/com/baeldung/web/UserController.java

@@ -0,0 +1,27 @@
+package com.baeldung.web;
+
+import com.baeldung.service.UserService;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/users")
+public class UserController {
+
+    private final UserService userService;
+
+    public UserController(UserService userService) {
+        this.userService = userService;
+    }
+
+    @GetMapping("/{username}")
+    public ResponseEntity<?> findOne(@PathVariable String username) {
+        return userService.findOne(username)
+                .map(DetailedUserDto::fromEntity)
+                .map(ResponseEntity::ok)
+                .orElse(ResponseEntity.notFound().build());
+    }
+}