Java – Spring boot + jpa lazy fetch

hibernatejavajpaspringspring-mvc

I'm new here, I hope you can help me guys.

I have a problem with the lazy fetch type.

I don't like to fetch all relationship, just if I need that.
When I use CommandLineRunner.run method, it's okay, it's fetching Lazily, but if I call that method from RestController, it's always fetching eagerly but I don't want that.

I tried:

with DTO and without DTO object.
upgrade all dependencies to the newest version.
Change @RestController annotation to @Controller
@Query annotation with LEFT JOIN FETCH on a custom method in the Repository
@Lazy(value=true)
@Basic(fetch = FetchType.LAZY)
@LazyCollection(value = LazyCollectionOption.TRUE)
@LazyToOne(value = LazyToOneOption.NO_PROXY)
@ElementCollection(fetch = FetchType.LAZY)
And sure, I tried to put fetch = FetchType.LAZY and into the @ManyToMany, @ManyToOne… annotation and with cascade things too.
Using @PersistenceContext private EntityManager manager with createQuery();

and finally, I'm using spring security with CustomUserDetailsService. When I log in it returns with the User object.
If the @Transactional annotation is on the ServiceImpl class it's fetching eagerly, but if I remove that annotation, it's fetch Lazily, but this is only working on login.

Do you have any idea?

Repository:

import hu.pte.clms.model.domain.User;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long>, JpaSpecificationExecutor{
}

ServiceImpl:

import hu.pte.clms.model.domain.User;
import hu.pte.clms.repository.UserRepository;
import hu.pte.clms.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
@Transactional
public class UserServiceImpl implements UserService{

    @Autowired
    private UserRepository userRepository;

    @Override
    public List<User> listAll(){
        return userRepository.findAll();
    }

    /* And another methods with this scheme */

Controller:

import hu.pte.clms.model.domain.User;
import hu.pte.clms.model.dto.UserDTO;
import hu.pte.clms.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.stream.Collectors;

@RestController
@RequestMapping("/api")
public class UserController{

    @Autowired
    private UserService userService;

    @RequestMapping(value = "/user/all", method = RequestMethod.GET)
    public ResponseEntity<List<UserDTO>> listAll(){
        return new ResponseEntity<>(userService.listAll().stream().map(user ->
                new UserDTO(user.getId(), user.getFirstName(), user.getLastName(), user.getCity(), user.getCountry(), user.getBio(), user.getPictureUrl())).collect(Collectors.toList()), HttpStatus.OK);
        }

    @RequestMapping(value = "/auth/user")
    public LoginResult get(){
        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
        if(!auth.getName().equals("anonymousUser")){
            User user = userService.findByUsername(auth.getName());
            return new LoginResult(auth.getName(), auth.getAuthorities(), user);
        }
        return null;
    }
}

LoginResult:

import hu.pte.clms.model.domain.User;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;

import java.util.Collection;
import java.util.List;

public class LoginResult implements UserDetails{
    private String password;
    private String name;
    private User user;
    private Collection<? extends GrantedAuthority> authorities;

    public LoginResult(String name, Collection<? extends GrantedAuthority> authorities, User user){
        this.name = name;
        this.authorities = authorities;
        this.user = user;
    }

    public LoginResult(String username, String s, boolean b, boolean userNonExpired, boolean credentialsNonExpired, boolean userNonLocked, Collection<? extends GrantedAuthority> authorities){}

    public LoginResult(String username, String password, List<GrantedAuthority> grantedAuthorities){
        this.name = username;
        this.password = password;
        this.authorities = grantedAuthorities;
    }

User:

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonInclude;
import hu.pte.clms.model.domain.relationship.UserSkill;

import javax.persistence.*;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

@Entity
@Table(name = "USER")
@JsonIgnoreProperties(ignoreUnknown = true)
@JsonInclude(value = JsonInclude.Include.NON_NULL)
public class User implements Serializable{

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue
    private Long id;

    @Column(name = "USERNAME")
    private String username;

    @Column(name = "PASSWORD")
    private String password;

    @Column(name = "FIRST_NAME")
    private String firstName;

    @Column(name = "LAST_NAME")
    private String lastName;

    @Column(name = "AGE")
    private Short age;

    @Column(name = "SEX")
    private String sex;

    @Column(name = "PHONE")
    private String phone;

    @Column(name = "SKYPE")
    private String skype;

    @Column(name = "PRIMARY_EMAIL")
    private String primaryEmail;

    @Column(name = "SECONDARY_EMAIL")
    private String secondaryEmail;

    @Column(name = "CITY")
    private String city;

    @Column(name = "COUNTRY")
    private String country;

    @Column(name = "BIO")
    private String bio;

    @Column(name = "PICTURE_URL")
    private String pictureUrl;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "CONFIG_ID")
    private Config config;

    @JsonIgnore
    @ManyToMany
    @JoinTable(name = "REL_USER_ROLE", joinColumns = {@JoinColumn(name = "USER_ID")}, inverseJoinColumns = {@JoinColumn(name = "ROLE_ID")})
    private List<Role> roles = new ArrayList<>();

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "REL_USER_SECURITY_ROLE", joinColumns = {@JoinColumn(name = "USER_ID")}, inverseJoinColumns = {@JoinColumn(name = "SECURITY_ROLE_ID")})
    private List<SecurityRole> securityRoles = new ArrayList<>();

    @ManyToMany(mappedBy = "user")
    private List<UserSkill> skills = new ArrayList<>();

    @JsonIgnore
    @ManyToMany
    @JoinTable(name = "REL_USER_PROJECT", joinColumns = {@JoinColumn(name = "USER_ID")}, inverseJoinColumns = {@JoinColumn(name = "PROJECT_ID")})
    private List<Project> projects = new ArrayList<>();

    @JsonIgnore
    @OneToMany(mappedBy = "reviewed", cascade = CascadeType.ALL)
    private List<Review> reviews = new ArrayList<>();

 /*Getters & setters*/

UserDTO:

import com.fasterxml.jackson.annotation.JsonInclude;
import hu.pte.clms.model.domain.*;
import hu.pte.clms.model.domain.relationship.UserSkill;
import java.util.ArrayList;
import java.util.List;

@JsonInclude(JsonInclude.Include.NON_EMPTY)
public class UserDTO{

    private Long id;
    private String username;
    private String password;
    private String firstName;
    private String lastName;
    private Short age;
    private String sex;
    private String phone;
    private String skype;
    private String primaryEmail;
    private String secondaryEmail;
    private String city;
    private String country;
    private String bio;
    private String pictureUrl;
    private Config config;
    private List<Role> roles = new ArrayList<>();
    private List<SecurityRole> securityRoles = new ArrayList<>();
    private List<UserSkill> skills = new ArrayList<>();
    private List<Project> projects = new ArrayList<>();
    private List<Review> reviews = new ArrayList<>();

    public UserDTO(){
    }

    public UserDTO(User user){
        this.id = user.getId();
        this.username = user.getUsername();
        this.password = user.getPassword();
        this.firstName = user.getFirstName();
        this.lastName = user.getLastName();
        this.age = user.getAge();
        this.sex = user.getSex();
        this.phone = user.getPhone();
        this.skype = user.getSkype();
        this.primaryEmail = user.getPrimaryEmail();
        this.secondaryEmail = user.getSecondaryEmail();
        this.city = user.getCity();
        this.country = user.getCountry();
        this.bio = user.getBio();
        this.pictureUrl = user.getPictureUrl();
        this.config = user.getConfig();
        this.roles = user.getRoles();
        this.securityRoles = user.getSecurityRoles();
        this.skills = user.getSkills();
        this.projects = user.getProjects();
        this.reviews = user.getReviews();
    }

    public UserDTO(Long id, String firstName, String lastName, String city, String country, String bio, String pictureUrl){
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.city = city;
        this.country = country;
        this.bio = bio;
        this.pictureUrl = pictureUrl;
    }
    /*Getters & setters*/
}

Application.java:

import hu.pte.clms.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application implements CommandLineRunner{

    @Autowired
    private UserService userService;

    public static void main(String[] args) {
        SpringApplication app = new SpringApplication(Application.class);
        app.setShowBanner(false);
        app.setRegisterShutdownHook(true);  
    }

    @Override
    public void run(String... strings) throws Exception{
        userService.listAll();
    }
}

pom.xml:

    ...

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.2.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.4.1</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>${spring.boot.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
            <version>${spring.boot.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
            <version>${spring.boot.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
            <version>${spring.boot.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.1.4.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>4.1.4.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>
    </dependencies>

Application.yml:

spring.datasource:
  url: jdbc:mysql://localhost:3306/clms?autoReconnect=true
  username: clms
  password: clms
  testOnBorrow: true
  validationQuery: SELECT 1
  driverClassName: com.mysql.jdbc.Driver

Best Answer

**Sorry I cannot really write a comment so I am writing here.

The only thing I could see here is the @Transactional annotation in service class and default propagation is required.

One another thing, in Jackson @JsonIgnoreProperties and @JsonIgnore does not work along. Better put the properties to ignore in the @JsonIgnoreProperties(value = {"projects", "reviews"})

I hope this will help.

Related Solutions

JPA EntityManager: Why use persist() over merge()

Either way will add an entity to a PersistenceContext, the difference is in what you do with the entity afterwards.

Persist takes an entity instance, adds it to the context and makes that instance managed (ie future updates to the entity will be tracked).

Merge returns the managed instance that the state was merged to. It does return something what exists in PersistenceContext or creates a new instance of your entity. In any case, it will copy the state from the supplied entity, and return managed copy. The instance you pass in will not be managed (any changes you make will not be part of the transaction - unless you call merge again). Though you can use the returned instance (managed one).

Maybe a code example will help.

MyEntity e = new MyEntity();

// scenario 1
// tran starts
em.persist(e); 
e.setSomeField(someValue); 
// tran ends, and the row for someField is updated in the database

// scenario 2
// tran starts
e = new MyEntity();
em.merge(e);
e.setSomeField(anotherValue); 
// tran ends but the row for someField is not updated in the database
// (you made the changes *after* merging)
      
// scenario 3
// tran starts
e = new MyEntity();
MyEntity e2 = em.merge(e);
e2.setSomeField(anotherValue); 
// tran ends and the row for someField is updated
// (the changes were made to e2, not e)

Scenario 1 and 3 are roughly equivalent, but there are some situations where you'd want to use Scenario 2.

Java – Difference between FetchType LAZY and EAGER in Java Persistence API

Sometimes you have two entities and there's a relationship between them. For example, you might have an entity called University and another entity called Student and a University might have many Students:

The University entity might have some basic properties such as id, name, address, etc. as well as a collection property called students that returns the list of students for a given university:

public class University {
   private String id;
   private String name;
   private String address;
   private List<Student> students;

   // setters and getters
}

Now when you load a University from the database, JPA loads its id, name, and address fields for you. But you have two options for how students should be loaded:

To load it together with the rest of the fields (i.e. eagerly), or
To load it on-demand (i.e. lazily) when you call the university's getStudents() method.

When a university has many students it is not efficient to load all of its students together with it, especially when they are not needed and in suchlike cases you can declare that you want students to be loaded when they are actually needed. This is called lazy loading.

Here's an example, where students is explicitly marked to be loaded eagerly:

@Entity
public class University {

    @Id
    private String id;

    private String name;

    private String address;

    @OneToMany(fetch = FetchType.EAGER)
    private List<Student> students;

    // etc.    
}

And here's an example where students is explicitly marked to be loaded lazily:

@Entity
public class University {

    @Id
    private String id;

    private String name;

    private String address;

    @OneToMany(fetch = FetchType.LAZY)
    private List<Student> students;

    // etc.
}

Best Answer

Related Solutions

JPA EntityManager: Why use persist() over merge()

Java – Difference between FetchType LAZY and EAGER in Java Persistence API

Related Topic