что то типо

demo/build.gradle

@@ -1,12 +1,23 @@
 plugins {
 	id 'java'
-	id 'org.springframework.boot' version '3.2.3'
+	id 'org.springframework.boot' version '3.2.4'
 	id 'io.spring.dependency-management' version '1.1.4'
 }
 
 group = 'com.example'
 version = '0.0.1-SNAPSHOT'
 
+defaultTasks 'bootRun'
+
+jar {
+    enabled = false
+}
+
+bootJar {
+    archiveFileName = String.format('%s-%s.jar', rootProject.name, version)
+}
+
+assert System.properties['java.specification.version'] == '17' || '21'
 java {
 	sourceCompatibility = '17'
 }
@@ -21,6 +32,9 @@ dependencies {
 	implementation 'org.springdoc:springdoc-openapi-starter-webmvc-ui:2.3.0'
 	implementation 'org.modelmapper:modelmapper:3.2.0'
 
+	implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
+	implementation 'com.h2database:h2:2.2.224'
+
 	testImplementation 'org.springframework.boot:spring-boot-starter-test'
 }
 

demo/src/main/java/com/example/demo/DemoApplication.java

@@ -44,15 +44,15 @@ public class DemoApplication implements CommandLineRunner {
 
 			log.info("Create default groups values");
 
-			final var group1 = groupService.create(new GroupEntity(null,user1, "1"));
-			final var group2 = groupService.create(new GroupEntity(null,user2, "2"));
-			final var group3 = groupService.create(new GroupEntity(null,user1, "3"));
+			final var group1 = groupService.create(user1.getId(), new GroupEntity(null,user1, "1"));
+			final var group2 = groupService.create(user2.getId(), new GroupEntity(null,user2, "2"));
+			final var group3 = groupService.create(user1.getId(), new GroupEntity(null,user1, "3"));
 
 			log.info("Create default members values");
 
-			final var member1 = memberService.create(new MemberEntity(null, group1, "mem1", "handle1", "expert"));
-			final var member2 = memberService.create(new MemberEntity(null, group1, "mem2", "handle2", "expert"));
-			final var member3 = memberService.create(new MemberEntity(null, group2,"mem3", "handle3", "expert"));
+			final var member1 = memberService.create(group1.getId(), new MemberEntity(null, group1, "mem1", "handle1", "expert"));
+			final var member2 = memberService.create(group1.getId(), new MemberEntity(null, group1, "mem2", "handle2", "expert"));
+			final var member3 = memberService.create(group2.getId(), new MemberEntity(null, group2,"mem3", "handle3", "expert"));
 
 		}
 	}

demo/src/main/java/com/example/demo/core/configuration/Constants.java

@@ -1,7 +1,10 @@
 package com.example.demo.core.configuration;
 
 public class Constants {
+    public static final String SEQUENCE_NAME = "hibernate_sequence";
+
     public static final String API_URL = "/api/1.0";
+
     private Constants() {
     }
 }

demo/src/main/java/com/example/demo/core/error/NotFoundException.java

@@ -1,7 +1,7 @@
 package com.example.demo.core.error;
 
 public class NotFoundException extends RuntimeException {
-    public NotFoundException(Long id) {
-        super(String.format("Entity with id [%s] is not found or not exists", id));
+    public <T> NotFoundException(Class<T> clazz, Long id) {
+        super(String.format("%s with id [%s] is not found or not exists", clazz.getSimpleName(), id));
     }
 }

demo/src/main/java/com/example/demo/core/model/BaseEntity.java

@@ -1,15 +1,23 @@
 package com.example.demo.core.model;
 
+import com.example.demo.core.configuration.Constants;
+
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.MappedSuperclass;
+import jakarta.persistence.SequenceGenerator;
+
+@MappedSuperclass
 public abstract class BaseEntity {
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = Constants.SEQUENCE_NAME)
+    @SequenceGenerator(name = Constants.SEQUENCE_NAME, sequenceName = Constants.SEQUENCE_NAME, allocationSize = 1)
     protected Long id;
 
     protected BaseEntity() {
     }
 
-    protected BaseEntity(Long id) {
-        this.id = id;
-    }
-
     public Long getId() {
         return id;
     }

demo/src/main/java/com/example/demo/core/repository/CommonRepository.java

@@ -1,17 +0,0 @@
-package com.example.demo.core.repository;
-
-import java.util.List;
-
-public interface CommonRepository<E, T> {
-    List<E> getAll();
-
-    E get(T id);
-
-    E create(E entity);
-
-    E update(E entity);
-
-    E delete(E entity);
-
-    void deleteAll();
-}

demo/src/main/java/com/example/demo/core/repository/MapRepository.java

@@ -1,57 +0,0 @@
-package com.example.demo.core.repository;
-
-import java.util.List;
-import java.util.Map;
-import java.util.TreeMap;
-
-import com.example.demo.core.model.BaseEntity;
-
-public abstract class MapRepository<E extends BaseEntity> implements CommonRepository<E, Long> {
-    private final Map<Long, E> entities = new TreeMap<>();
-    private Long lastId = 0L;
-
-    protected MapRepository() {
-    }
-
-    @Override
-    public List<E> getAll() {
-        return entities.values().stream().toList();
-    }
-
-    @Override
-    public E get(Long id) {
-        return entities.get(id);
-    }
-
-    @Override
-    public E create(E entity) {
-        lastId++;
-        entity.setId(lastId);
-        entities.put(lastId, entity);
-        return entity;
-    }
-
-    @Override
-    public E update(E entity) {
-        if (get(entity.getId()) == null) {
-            return null;
-        }
-        entities.put(entity.getId(), entity);
-        return entity;
-    }
-
-    @Override
-    public E delete(E entity) {
-        if (get(entity.getId()) == null) {
-            return null;
-        }
-        entities.remove(entity.getId());
-        return entity;
-    }
-
-    @Override
-    public void deleteAll() {
-        lastId = 0L;
-        entities.clear();
-    }
-}

demo/src/main/java/com/example/demo/groups/api/GroupController.java

@@ -45,27 +45,36 @@ public class GroupController {
     }
 
     @GetMapping
-    public List<GroupDto> getAll(@RequestParam(name = "userId", defaultValue = "0") Long userId) {
-        return groupService.getAll(userId).stream().map(this::toDto).toList();
+    public List<GroupDto> getAll(
+            @PathVariable(name = "user") Long userId) {
+        return groupService.getAll(userId).stream()
+                .map(this::toDto)
+                .toList();
     }
 
     @GetMapping("/{id}")
-    public GroupDto get(@PathVariable(name = "id") Long id) {
+    public GroupDto get(
+            @PathVariable(name = "id") Long id) {
         return toDto(groupService.get(id));
     }
 
     @PostMapping
-    public GroupDto create(@RequestBody @Valid GroupDto dto) {
-        return toDto(groupService.create(toEntity(dto)));
+    public GroupDto create(
+            @PathVariable(name = "user") Long userId,
+            @RequestBody @Valid GroupDto dto) {
+        return toDto(groupService.create(userId, toEntity(dto)));
     }
 
     @PutMapping("/{id}")
-    public GroupDto update(@PathVariable(name = "id") Long id, @RequestBody GroupDto dto) {
+    public GroupDto update(
+            @PathVariable(name = "id") Long id,
+            @RequestBody @Valid GroupDto dto) {
         return toDto(groupService.update(id, toEntity(dto)));
     }
 
     @DeleteMapping("/{id}")
-    public GroupDto delete(@PathVariable(name = "id") @Valid Long id) {
+    public GroupDto delete(
+            @PathVariable(name = "id") Long id) {
         return toDto(groupService.delete(id));
     }
 }

demo/src/main/java/com/example/demo/groups/api/GroupDto.java

@@ -3,17 +3,18 @@ package com.example.demo.groups.api;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
 import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 
 public class GroupDto {
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
     private Long id;
     @NotNull
     @Min(1)
     private Long userId;
-    @NotNull
+    @NotBlank
     private String name;
 
-    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
     public Long getId() {
         return id;
     }

demo/src/main/java/com/example/demo/groups/model/GroupEntity.java

@@ -1,20 +1,38 @@
 package com.example.demo.groups.model;
 
+import java.util.HashSet;
 import java.util.Objects;
+import java.util.Set;
 
 import com.example.demo.core.model.BaseEntity;
+import com.example.demo.members.model.MemberEntity;
 import com.example.demo.users.model.UserEntity;
 
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.OrderBy;
+import jakarta.persistence.Table;
+
+@Entity
+@Table(name = "groups")
 public class GroupEntity extends BaseEntity {
+    @ManyToOne
+    @JoinColumn(name = "typeId", nullable = false)
     private UserEntity user;
+    @Column(nullable = false, length = 30)
     private String name;
+    @OneToMany(mappedBy = "group", cascade = CascadeType.ALL)
+    @OrderBy("id ASC")
+    private Set<MemberEntity> members = new HashSet<>();
 
     public GroupEntity() {
-        super();
     }
 
     public GroupEntity(Long id, UserEntity user, String name) {
-        super(id);
         this.user = user;
         this.name = name;
     }
@@ -35,6 +53,24 @@ public class GroupEntity extends BaseEntity {
         this.name = name;
     }
 
+    public Set<MemberEntity> getMembers() {
+        return members;
+    }
+
+    public void addMember(MemberEntity member) {
+        if (member.getGroup() != this) {
+            member.setGroup(null);
+        }
+        members.add(member);
+    }
+
+    public void delterMember(MemberEntity member) {
+        if (member.getGroup() != this) {
+            return;
+        }
+        members.remove(member);
+    }
+
     @Override
     public int hashCode() {
         return Objects.hash(id, name, user);
@@ -49,6 +85,7 @@ public class GroupEntity extends BaseEntity {
         final GroupEntity other = (GroupEntity) obj;
         return Objects.equals(other.getId(), id)
                 && Objects.equals(other.getName(), name)
-                && Objects.equals(other.getUser(), user);
+                && Objects.equals(other.getUser(), user)
+                && Objects.equals(other.getMembers(), members);
     }
 }

demo/src/main/java/com/example/demo/groups/repository/GroupRepository.java

@@ -1,10 +1,16 @@
 package com.example.demo.groups.repository;
 
-import org.springframework.stereotype.Repository;
+import java.util.List;
+import java.util.Optional;
 
-import com.example.demo.core.repository.MapRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.CrudRepository;
+
+import com.example.demo.groups.model.GroupEntity;
 import com.example.demo.groups.model.GroupEntity;
 
-@Repository
-public class GroupRepository extends MapRepository<GroupEntity> {
-}
+public interface GroupRepository extends CrudRepository<GroupEntity, Long> {
+    Optional<GroupEntity> findOneById(long id);
+
+    List<GroupEntity> findByUserId(long userId);
+}

demo/src/main/java/com/example/demo/groups/service/GroupService.java

@@ -1,55 +1,69 @@
 package com.example.demo.groups.service;
 
 import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+
+import javax.swing.GroupLayout.Group;
 
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 import com.example.demo.core.error.NotFoundException;
 import com.example.demo.groups.model.GroupEntity;
 import com.example.demo.groups.repository.GroupRepository;
 import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.repository.UserRepository;
+import com.example.demo.users.service.UserService;
 
 @Service
 public class GroupService {
     private final GroupRepository repository;
+    private final UserService userService;
 
-    public GroupService(GroupRepository repository) {
+    public GroupService(GroupRepository repository, UserService userService) {
         this.repository = repository;
+        this.userService = userService;
     }
 
+    @Transactional(readOnly = true)
     public List<GroupEntity> getAll(Long userId) {
-        if (Objects.equals(userId, 0L)) {
-            return repository.getAll();
+        userService.get(userId);
+        return repository.findByUserId(userId);
+    }
+
+    @Transactional(readOnly = true)
+    public GroupEntity get(long id) {
+        return repository.findById(id)
+                .orElseThrow(() -> new NotFoundException(GroupEntity.class, id));
+    }
+
+    @Transactional
+    public GroupEntity create(long userId, GroupEntity entity) {
+        if (entity == null) {
+            throw new IllegalArgumentException("Entity is null");
         }
-        return repository.getAll().stream()
-                .filter(item -> item.getUser().getId().equals(userId))
-                .toList();
+        final UserEntity existsUser = userService.get(userId);
+        entity.setUser(existsUser);
+        return repository.save(entity);
     }
 
-    public GroupEntity get(Long id) {
-        return Optional.ofNullable(repository.get(id))
-                .orElseThrow(() -> new NotFoundException(id));
-    }
 
-    public GroupEntity create(GroupEntity entity) {
-        return repository.create(entity);
-    }
-
-    public GroupEntity update(Long id, GroupEntity entity) {
+    @Transactional
+    public GroupEntity update(long id, GroupEntity entity) {
         final GroupEntity existsEntity = get(id);
         existsEntity.setName(entity.getName());
-        existsEntity.setUser(entity.getUser());
-        return repository.update(existsEntity);
+        return repository.save(existsEntity);
     }
 
-    public GroupEntity delete(Long id) {
+    @Transactional
+    public GroupEntity delete(long id) {
         final GroupEntity existsEntity = get(id);
-        return repository.delete(existsEntity);
+        repository.delete(existsEntity);
+        return existsEntity;
     }
 
+    @Transactional
     public void clear(){
         repository.deleteAll();
     }
+
 }

demo/src/main/java/com/example/demo/members/api/MemberController.java

@@ -55,7 +55,7 @@ public class MemberController {
 
     @PostMapping
     public MemberDto create(@RequestBody @Valid MemberDto dto) {
-        return toDto(memberService.create(toEntity(dto)));
+        return toDto(memberService.create(dto.getGroupId(), toEntity(dto)));
     }
 
     @PutMapping("/{id}")

demo/src/main/java/com/example/demo/members/api/MemberDto.java

@@ -3,21 +3,22 @@ package com.example.demo.members.api;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
 import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 
 public class MemberDto {
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
     private Long id;
     @NotNull
     @Min(1)
     private Long groupId;
-    @NotNull
+    @NotBlank
     private String name;
-    @NotNull
+    @NotBlank
     private String handle;
-    @NotNull
+    @NotBlank
     private String rank;
 
-    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
     public Long getId() {
         return id;
     }

demo/src/main/java/com/example/demo/members/model/MemberEntity.java

@@ -4,17 +4,31 @@ import java.util.Objects;
 
 import com.example.demo.core.model.BaseEntity;
 import com.example.demo.groups.model.GroupEntity;
+import com.example.demo.users.model.UserEntity;
 
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+
+@Entity
+@Table(name = "members")
 public class MemberEntity extends BaseEntity {
+    @ManyToOne
+    @JoinColumn(name = "typeId", nullable = false)
     private GroupEntity group;
-    private String name, handle, rank;
+    @Column(nullable = false, length = 50)
+    private String name;
+    @Column(nullable = false, length = 35)
+    private String handle;
+    @Column(nullable = false,  length = 30)
+    private String rank;
 
     public MemberEntity() {
-        super();
     }
 
     public MemberEntity(Long id, GroupEntity group, String name, String handle, String rank) {
-        super(id);
         this.group = group;
         this.name = name;
         this.handle = handle;

demo/src/main/java/com/example/demo/members/repository/MemberRepository.java

@@ -2,9 +2,17 @@ package com.example.demo.members.repository;
 
 import org.springframework.stereotype.Repository;
 
-import com.example.demo.core.repository.MapRepository;
 import com.example.demo.members.model.MemberEntity;
 
-@Repository
-public class MemberRepository extends MapRepository<MemberEntity> {
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.CrudRepository;
+
+public interface MemberRepository extends CrudRepository<MemberEntity, Long> {
+    Optional<MemberEntity> findOneById(long id);
+
+    List<MemberEntity> findByGroupId(long groupId);
+
 }

demo/src/main/java/com/example/demo/members/service/MemberService.java

@@ -1,55 +1,66 @@
 package com.example.demo.members.service;
 
 import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
 
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 import com.example.demo.core.error.NotFoundException;
+import com.example.demo.groups.model.GroupEntity;
+import com.example.demo.groups.service.GroupService;
 import com.example.demo.members.model.MemberEntity;
 import com.example.demo.members.repository.MemberRepository;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.service.UserService;
 
 @Service
 public class MemberService {
     private final MemberRepository repository;
+    private final GroupService groupService;
 
-    public MemberService(MemberRepository repository) {
+    public MemberService(MemberRepository repository, GroupService groupService) {
         this.repository = repository;
+        this.groupService = groupService;
     }
 
-    public List<MemberEntity> getAll(Long groupId) {
-        if (Objects.equals(groupId, 0L)) {
-            return repository.getAll();
+    @Transactional(readOnly = true)
+    public List<MemberEntity> getAll(long groupId) {
+        return repository.findByGroupId(groupId);
+    }
+
+    @Transactional(readOnly = true)
+    public MemberEntity get(long id) {
+        return repository.findOneById(id)
+                .orElseThrow(() -> new NotFoundException(MemberEntity.class, id));
+    }
+    @Transactional
+    public MemberEntity create(long groupId, MemberEntity entity) {
+        if (entity == null) {
+            throw new IllegalArgumentException("Entity is null");
         }
-        return repository.getAll().stream()
-                .filter(item -> item.getGroup().getId().equals(groupId))
-                .toList();
+        final GroupEntity existsGroup = groupService.get(groupId);
+        entity.setGroup(existsGroup);
+        return repository.save(entity);
     }
 
-    public MemberEntity get(Long id) {
-        return Optional.ofNullable(repository.get(id))
-                .orElseThrow(() -> new NotFoundException(id));
-    }
-
-    public MemberEntity create(MemberEntity entity) {
-        return repository.create(entity);
-    }
-
-    public MemberEntity update(Long id, MemberEntity entity) {
+    @Transactional
+    public MemberEntity update(long id, MemberEntity entity) {
         final MemberEntity existsEntity = get(id);
-        existsEntity.setGroup(entity.getGroup());
-        existsEntity.setName(entity.getName());
         existsEntity.setHandle(entity.getHandle());
+        existsEntity.setName(entity.getName());
         existsEntity.setRank(entity.getRank());
-        return repository.update(existsEntity);
+        
+        return repository.save(existsEntity);
     }
 
-    public MemberEntity delete(Long id) {
+    @Transactional
+    public MemberEntity delete(long id) {
         final MemberEntity existsEntity = get(id);
-        return repository.delete(existsEntity);
+        repository.delete(existsEntity);
+        return existsEntity;
     }
 
+    @Transactional
     public void clear(){
         repository.deleteAll();
     }

demo/src/main/java/com/example/demo/users/api/UserDto.java

@@ -1,20 +1,25 @@
 package com.example.demo.users.api;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonProperty.Access;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
 
-import jakarta.validation.constraints.Min;
-import jakarta.validation.constraints.NotNull;
 
 public class UserDto {
+    @JsonProperty(access = Access.READ_ONLY)
     private Long id;
-    @NotNull
+    @NotBlank
+    @Size(min = 3, max = 25)
     private String handle;
-    @NotNull
+    @NotBlank
+    @Size(min = 3, max = 30)
     private String email;
-    @NotNull
+    @NotBlank
+    @Size(min = 3, max = 20)
     private String password;
 
-    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
     public Long getId() {
         return id;
     }

demo/src/main/java/com/example/demo/users/model/UserEntity.java

@@ -1,22 +1,38 @@
 package com.example.demo.users.model;
-import java.util.Objects;
 
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+import javax.swing.GroupLayout.Group;
 
 import com.example.demo.core.model.BaseEntity;
+import com.example.demo.groups.model.GroupEntity;
 
-import jakarta.validation.OverridesAttribute;
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.OrderBy;
+import jakarta.persistence.Table;
 
+@Entity
+@Table(name = "users")
 public class UserEntity extends BaseEntity{
+    @Column(nullable = false, unique = true, length = 25)
     private String handle;
+    @Column(nullable = false, unique = true, length = 30)
     private String email;
+    @Column(nullable = false, length = 20)
     private String password;
+    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
+    @OrderBy("id ASC")
+    private Set<GroupEntity> groups = new HashSet<>();
 
     public UserEntity(){
-        super();
     }
 
     public UserEntity(Long id, String handle, String email, String password) {
-        super(id);
         this.handle = handle;
         this.email = email;
         this.password = password;
@@ -46,6 +62,24 @@ public class UserEntity extends BaseEntity{
         this.handle = handle;
     }
 
+    public Set<GroupEntity> getGroups() {
+        return groups;
+    }
+
+    public void addGroup(GroupEntity group) {
+        if (group.getUser() != this) {
+            group.setUser(this);
+        }
+        groups.add(group);
+    }
+
+    public void deleteGroup(GroupEntity group) {
+        if (group.getUser() != this) {
+            return;
+        }
+        groups.remove(group);
+    }
+
     @Override
     public int hashCode() {
         return Objects.hash(id, handle, email, password);
@@ -61,7 +95,8 @@ public class UserEntity extends BaseEntity{
         return Objects.equals(other.getId(), id)
                 && Objects.equals(other.getHandle(), handle)
                 && Objects.equals(other.getEmail(), email)
-                && Objects.equals(other.getPassword(), password);
+                && Objects.equals(other.getPassword(), password)
+                && Objects.equals(other.getGroups(), groups);
     }
 
 }

demo/src/main/java/com/example/demo/users/repository/UserRepository.java

@@ -1,10 +1,12 @@
 package com.example.demo.users.repository;
 
-import org.springframework.stereotype.Repository;
+import java.util.Optional;
+
+import org.springframework.data.repository.CrudRepository;
 
-import com.example.demo.core.repository.MapRepository;
 import com.example.demo.users.model.UserEntity;
 
-@Repository
-public class UserRepository extends MapRepository<UserEntity> {
+public interface UserRepository extends CrudRepository<UserEntity, Long> {
+    Optional<UserEntity> findByHandleIgnoreCase(String login);
+    Optional<UserEntity> findByEmailIgnoreCase(String login);
 }

demo/src/main/java/com/example/demo/users/service/UserService.java

@@ -2,9 +2,10 @@ package com.example.demo.users.service;
 
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
+import java.util.stream.StreamSupport;
 
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 import com.example.demo.core.error.NotFoundException;
 import com.example.demo.users.model.UserEntity;
@@ -18,32 +19,62 @@ public class UserService {
         this.repository = repository;
     }
 
+    private void checkHandle(String handle) {
+        if (repository.findByHandleIgnoreCase(handle).isPresent()) {
+            throw new IllegalArgumentException(
+                    String.format("User with handle %s is already exists", handle));
+        }
+    }
+
+    private void checkEmail(String email) {
+        if (repository.findByHandleIgnoreCase(email).isPresent()) {
+            throw new IllegalArgumentException(
+                    String.format("User with email %s is already exists", email));
+        }
+    }
+
+    @Transactional(readOnly = true)
     public List<UserEntity> getAll() {
-        return repository.getAll();
+        return StreamSupport.stream(repository.findAll().spliterator(), false).toList();
     }
 
-    public UserEntity get(Long id) {
-        return Optional.ofNullable(repository.get(id))
-                .orElseThrow(() -> new NotFoundException(id));
+    @Transactional(readOnly = true)
+    public UserEntity get(long id) {
+        return repository.findById(id)
+                .orElseThrow(() -> new NotFoundException(UserEntity.class, id));
     }
 
+    @Transactional
     public UserEntity create(UserEntity entity) {
-        return repository.create(entity);
+        if (entity == null) {
+            throw new IllegalArgumentException("Entity is null");
+        }
+        checkHandle(entity.getHandle());
+        checkEmail(entity.getEmail());
+        repository.save(entity);
+        return repository.save(entity);
     }
 
-    public UserEntity update(Long id, UserEntity entity) {
+    @Transactional
+    public UserEntity update(long id, UserEntity entity) {
         final UserEntity existsEntity = get(id);
-        existsEntity.setEmail(entity.getEmail());
+        checkHandle(entity.getHandle());
+        checkEmail(entity.getEmail());
         existsEntity.setHandle(entity.getHandle());
+        existsEntity.setEmail(entity.getEmail());
         existsEntity.setPassword(entity.getPassword());
-        return repository.update(existsEntity);
+        repository.save(existsEntity);
+        return existsEntity;
     }
 
-    public UserEntity delete(Long id) {
+    @Transactional
+    public UserEntity delete(long id) {
         final UserEntity existsEntity = get(id);
-        return repository.delete(existsEntity);
+        repository.delete(existsEntity);
+        return existsEntity;
     }
 
+    @Transactional
     public void clear(){
         repository.deleteAll();
     }

demo/src/main/resources/application.properties

@@ -1 +1,19 @@
+spring.main.banner-mode=off
+server.port=8080
 
+# Logger settings
+# Available levels are: TRACE, DEBUG, INFO, WARN, ERROR, FATAL, OFF
+logging.level.com.example.demo=DEBUG
+
+# JPA Settings
+spring.datasource.url=jdbc:h2:file:./data
+spring.datasource.username=sa
+spring.datasource.password=password
+spring.datasource.driver-class-name=org.h2.Driver
+spring.jpa.hibernate.ddl-auto=create
+spring.jpa.open-in-view=false
+# spring.jpa.show-sql=true
+# spring.jpa.properties.hibernate.format_sql=true
+
+# H2 console
+spring.h2.console.enabled=true

demo/src/test/java/com/example/demo/GroupServiceTests.java

@@ -32,8 +32,8 @@ class GroupServiceTests {
 	@Order(1)
 	void createTest() {
 		var user = userService.create(new UserEntity(null, "Oleja123", "bebrus@mail.ru", "1234"));
-        groupService.create(new GroupEntity(null, user, "1"));
-        final GroupEntity last = groupService.create(new GroupEntity(null, user, "2"));
+        groupService.create(user.getId(), new GroupEntity(null, user, "1"));
+        final GroupEntity last = groupService.create(user.getId(), new GroupEntity(null, user, "2"));
 		Assertions.assertEquals(2, groupService.getAll(1L).size());
 		Assertions.assertEquals(last, groupService.get(2L));
 	}
@@ -59,8 +59,8 @@ class GroupServiceTests {
 		Assertions.assertEquals(1, groupService.getAll(1L).size());
 		final GroupEntity last = groupService.get(1L);
 		Assertions.assertEquals(1L, last.getId());
-
-		final GroupEntity newEntity = groupService.create(new GroupEntity(null, userService.get(1L), test));
+		final UserEntity user = userService.get(1L);
+		final GroupEntity newEntity = groupService.create(user.getId(), new GroupEntity(null, user, test));
 		Assertions.assertEquals(2, groupService.getAll(1L).size());
 		Assertions.assertEquals(3, newEntity.getId());
         userService.clear();

demo/src/test/java/com/example/demo/MemberServiceTests.java

@@ -37,9 +37,9 @@ class MemberServiceTests {
 	@Order(1)
 	void createTest() {
 		var user = userService.create(new UserEntity(null, "Oleja123", "bebrus@mail.ru", "1234"));
-        var group = groupService.create(new GroupEntity(null, user, "1"));
-        memberService.create(new MemberEntity(null, group, "1", "1", "1"));
-        var last = memberService.create(new MemberEntity(null, group, "2", "2", "2"));
+        var group = groupService.create(user.getId(), new GroupEntity(null, user, "1"));
+        memberService.create(group.getId(), new MemberEntity(null, group, "1", "1", "1"));
+        var last = memberService.create(group.getId(), new MemberEntity(null, group, "2", "2", "2"));
 		Assertions.assertEquals(2, memberService.getAll(1L).size());
 		Assertions.assertEquals(last, memberService.get(2L));
 	}
@@ -68,8 +68,8 @@ class MemberServiceTests {
 		Assertions.assertEquals(1, memberService.getAll(1L).size());
 		final MemberEntity last = memberService.get(1L);
 		Assertions.assertEquals(1L, last.getId());
-
-		final MemberEntity newEntity = memberService.create(new MemberEntity(null, groupService.get(1L), test,test,test));
+		final GroupEntity group =  groupService.get(1L);
+		final MemberEntity newEntity = memberService.create(group.getId(), new MemberEntity(null, group, test,test,test));
 		Assertions.assertEquals(2, memberService.getAll(1L).size());
 		Assertions.assertEquals(3, newEntity.getId());
         userService.clear();