Here are my ProjectController:

package db.lab6.projectmanagement.controller;

import db.lab6.projectmanagement.dto.MemberDto;
import db.lab6.projectmanagement.dto.ProjectDto;
import db.lab6.projectmanagement.entity.Member;
import db.lab6.projectmanagement.entity.Project;
import db.lab6.projectmanagement.service.ProjectService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Set;

@RestController
@RequestMapping("/projects")
public class ProjectController {

    private final ProjectService projectService;

    @Autowired
    public ProjectController(ProjectService projectService) {
        this.projectService = projectService;
    }

    @GetMapping("/{projectId}")
    private ResponseEntity<Project> getProject(@PathVariable Long projectId) {
        return ResponseEntity.ok(projectService.findById(projectId));
    }

    @PostMapping
    public ResponseEntity<Project> createProject(@RequestBody ProjectDto projectDto) {
        return ResponseEntity.status(HttpStatus.CREATED).body(projectService.create(projectDto));
    }

    @GetMapping("/{projectId}/members")
    public ResponseEntity<Set<Member>> getAllMembersFromProject(@PathVariable Long projectId) {
        return ResponseEntity.ok(projectService.findMembers(projectId));
    }
    
    // other mappings
}

Here are my ProjectService:

package db.lab6.projectmanagement.service.impl;

import db.lab6.projectmanagement.dto.MemberDto;
import db.lab6.projectmanagement.dto.ProjectDto;
import db.lab6.projectmanagement.entity.Member;
import db.lab6.projectmanagement.entity.Project;
import db.lab6.projectmanagement.entity.Role;
import db.lab6.projectmanagement.entity.User;
import db.lab6.projectmanagement.repository.MemberRepository;
import db.lab6.projectmanagement.repository.ProjectRepository;
import db.lab6.projectmanagement.service.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

@Service
public class ProjectServiceImpl implements ProjectService {

    private final ProjectRepository projectRepository;
    private final MemberRepository memberRepository;
    private final UserService userService;
    private final RoleService roleService;

    @Autowired
    public ProjectServiceImpl(ProjectRepository projectRepository,
                              MemberRepository memberRepository,
                              UserService userService,
                              RoleService roleService) {
        this.projectRepository = projectRepository;
        this.memberRepository = memberRepository;
        this.userService = userService;
        this.roleService = roleService;
    }

    @Override
    public Project findById(Long id) {
        return projectRepository.findById(id).orElseThrow(() ->
                new ProjectNotFoundException(id));
    }

    @Override
    public Project create(ProjectDto projectDto) {

        User ownerUser = userService.findByNickname(projectDto.getOwnerNickname());

        Role ownerRole = roleService.findByName("OWNER");

        Member ownerMember = Member.builder()
                .user(ownerUser)
                .role(ownerRole).build();

        Set<Member> members = new HashSet<>();
        members.add(ownerMember);
        Project project = Project.builder()
                .name(projectDto.getName())
                .description(projectDto.getDescription())
                .members(members).build();
        return projectRepository.save(project);
    }

    @Override
    public Set<Member> findMembers(Long id) {
        Project project = findById(id);
        return project.getMembers();
    }

    // other methods
}

Project entity:

package db.lab6.projectmanagement.entity;

import com.fasterxml.jackson.annotation.JsonIgnore;
import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.HashSet;
import java.util.Set;

@AllArgsConstructor
@NoArgsConstructor
@Data
@Builder
@Entity
@Table(name = "projects")
public class Project {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false)
    private String name;

    private String description;

    @OneToMany(mappedBy = "project", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
    @JsonIgnore
    private Set<Task> tasks;

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(name = "project_member",
            joinColumns = @JoinColumn(name = "project_id"),
            inverseJoinColumns = @JoinColumn(name = "member_id"))
    private Set<Member> members;
}

Member enitity:

package db.lab6.projectmanagement.entity;

import com.fasterxml.jackson.annotation.JsonIgnore;
import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.HashSet;
import java.util.Set;


@AllArgsConstructor
@NoArgsConstructor
@Data
@Builder
@Entity
@Table(name = "members")
public class Member {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "user_id", nullable = false)
    private User user;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "role_id", nullable = false)
    private Role role;

    @ManyToMany(mappedBy = "members", fetch = FetchType.EAGER)
    @JsonIgnore
    private Set<Project> projects;
}

When I create a project, I get a project that includes members

t.ex.

{
    "id": 1,
    "name": "foo name",
    "description": "some description",
    "members": [
        {
            "id": 1,
            "user": {
                "id": 1,
                "email": "[email protected]",
                "nickname": "dimitri",
                "password": "123456"
            },
            "role": {
                "id": 1,
                "name": "OWNER"
            }
        }
    ]
}

But when I want to get the project I recieve

{
    "id": 1,
    "name": "foo name",
    "description": "some description",
    "members": []
}

The point is that the database contains a list of members tied to the project in project_member.

I tried to change fetch = FetchType.EAGER to FetchType.LAZY and vice versa but it didn’t help. I traced sql requests and they looked good. I even ran them in the database directly and it outputted everything correctly.

Here’s a trace of the sql request if needed

select
        p1_0.id,
        p1_0.description,
        m1_0.project_id,
        m1_1.id,
        m1_1.role_id,
        m1_1.user_id,
        p1_0.name 
    from
        projects p1_0 
    left join
        project_member m1_0 
            on p1_0.id=m1_0.project_id 
    left join
        members m1_1 
            on m1_1.id=m1_0.member_id 
    where
        p1_0.id=?