无法使用Spring Data JPA创建JOIN

Question

I'm new to Spring Data and tried to solve the issue by following this post on SO and some other tutorials but without much success.

I'm trying to make a simple Join using Spring Data JPA between 2 tables. The tables in the database are called: * user_vehicle -> contains information about all vehicles per user since 1 user can have many vehicles * vehicle_model which contains data about vehicle models (id, name, etc)

Current data in the database in the user_vehicle table:
ID | vehicle_id | user_id
1 | 1 | 1
2 | 2 | 1

Here is the code I've tried but can't get it to work (getters and setters are removed from the post to shorten it):

@Entity(name = "vehicle_model")
public class VehicleModel {

@Id
@Min(1)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private Long manufacturerId;
private String title;
private int ccm;
private int kw;
private int yearOfManufacture;
private int engineTypeId;
private boolean isActive;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "vehicle_id", insertable = false, updatable = false)
@Fetch(FetchMode.JOIN)
private UserVehicle userVehicle;
}


@Entity(name = "user_vehicle")
public class UserVehicle {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@Column(nullable = false)
private long vehicleId;
@Column(nullable = false)
private long userId;

@OneToMany(targetEntity = VehicleModel.class, mappedBy = "userVehicle", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
List<VehicleModel> vehicleModels;
}


@Repository
public interface UserVehicleRepository extends CrudRepository<UserVehicle, Long> 
{
    Iterable<UserVehicle> findVehicleModelsByUserId(Long userId);
}

I'm expecting to get 2 results in the iterable with filled vehicle_model data. Instead I get 2 results but for the vehicleModels property I get "Unable to evaluate the expression Method threw 'org.hibernate.exception.SQLGrammarException' exception."

Here is the output from the console:

2019-06-23 02:04:10.988 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select uservehicl0_.id as id1_1_, uservehicl0_.user_id as user_id2_1_, uservehicl0_.vehicle_id as vehicle_3_1_ from user_vehicle uservehicl0_ where uservehicl0_.user_id=? 2019-06-23 02:04:11.034 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select vehiclemod0_.vehicle_id as vehicle_9_4_0_, vehiclemod0_.id as id1_4_0_, vehiclemod0_.id as id1_4_1_, vehiclemod0_.ccm as ccm2_4_1_, vehiclemod0_.engine_type_id as engine_t3_4_1_, vehiclemod0_.is_active as is_activ4_4_1_, vehiclemod0_.kw as kw5_4_1_, vehiclemod0_.manufacturer_id as manufact6_4_1_, vehiclemod0_.title as title7_4_1_, vehiclemod0_.vehicle_id as vehicle_9_4_1_, vehiclemod0_.year_of_manufacture as year_of_8_4_1_ from vehicle_model vehiclemod0_ where vehiclemod0_.vehicle_id=? 2019-06-23 02:04:11.035 WARN 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 1054, SQLState: 42S22 2019-06-23 02:04:11.035 ERROR 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : Unknown column 'vehiclemod0_.vehicle_id' in 'field list' 2019-06-23 02:04:11.036 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select vehiclemod0_.vehicle_id as vehicle_9_4_0_, vehiclemod0_.id as id1_4_0_, vehiclemod0_.id as id1_4_1_, vehiclemod0_.ccm as ccm2_4_1_, vehiclemod0_.engine_type_id as engine_t3_4_1_, vehiclemod0_.is_active as is_activ4_4_1_, vehiclemod0_.kw as kw5_4_1_, vehiclemod0_.manufacturer_id as manufact6_4_1_, vehiclemod0_.title as title7_4_1_, vehiclemod0_.vehicle_id as vehicle_9_4_1_, vehiclemod0_.year_of_manufacture as year_of_8_4_1_ from vehicle_model vehiclemod0_ where vehiclemod0_.vehicle_id=? 2019-06-23 02:04:11.037 WARN 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 1054, SQLState: 42S22 2019-06-23 02:04:11.037 ERROR 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : Unknown column 'vehiclemod0_.vehicle_id' in 'field list' 2019-06-23 02:04:11.038 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select vehiclemod0_.vehicle_id as vehicle_9_4_0_, vehiclemod0_.id as id1_4_0_, vehiclemod0_.id as id1_4_1_, vehiclemod0_.ccm as ccm2_4_1_, vehiclemod0_.engine_type_id as engine_t3_4_1_, vehiclemod0_.is_active as is_activ4_4_1_, vehiclemod0_.kw as kw5_4_1_, vehiclemod0_.manufacturer_id as manufact6_4_1_, vehiclemod0_.title as title7_4_1_, vehiclemod0_.vehicle_id as vehicle_9_4_1_, vehiclemod0_.year_of_manufacture as year_of_8_4_1_ from vehicle_model vehiclemod0_ where vehiclemod0_.vehicle_id=? 2019-06-23 02:04:11.039 WARN 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 1054, SQLState: 42S22 2019-06-23 02:04:11.040 ERROR 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : Unknown column 'vehiclemod0_.vehicle_id' in 'field list' 2019-06-23 02:04:11.042 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select vehiclemod0_.vehicle_id as vehicle_9_4_0_, vehiclemod0_.id as id1_4_0_, vehiclemod0_.id as id1_4_1_, vehiclemod0_.ccm as ccm2_4_1_, vehiclemod0_.engine_type_id as engine_t3_4_1_, vehiclemod0_.is_active as is_activ4_4_1_, vehiclemod0_.kw as kw5_4_1_, vehiclemod0_.manufacturer_id as manufact6_4_1_, vehiclemod0_.title as title7_4_1_, vehiclemod0_.vehicle_id as vehicle_9_4_1_, vehiclemod0_.year_of_manufacture as year_of_8_4_1_ from vehicle_model vehiclemod0_ where vehiclemod0_.vehicle_id=? 2019-06-23 02:04:11.043 WARN 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 1054, SQLState: 42S22 2019-06-23 02:04:11.043 ERROR 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : Unknown column 'vehiclemod0_.vehicle_id' in 'field list' 2019-06-23 02:04:11.045 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select vehiclemod0_.vehicle_id as vehicle_9_4_0_, vehiclemod0_.id as id1_4_0_, vehiclemod0_.id as id1_4_1_, vehiclemod0_.ccm as ccm2_4_1_, vehiclemod0_.engine_type_id as engine_t3_4_1_, vehiclemod0_.is_active as is_activ4_4_1_, vehiclemod0_.kw as kw5_4_1_, vehiclemod0_.manufacturer_id as manufact6_4_1_, vehiclemod0_.title as title7_4_1_, vehiclemod0_.vehicle_id as vehicle_9_4_1_, vehiclemod0_.year_of_manufacture as year_of_8_4_1_ from vehicle_model vehiclemod0_ where vehiclemod0_.vehicle_id=? 2019-06-23 02:04:11.046 WARN 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 1054, SQLState: 42S22 2019-06-23 02:04:11.046 ERROR 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : Unknown column 'vehiclemod0_.vehicle_id' in 'field list' 2019-06-23 02:04:11.048 DEBUG 5896 --- [nio-8080-exec-1] org.hibernate.SQL : select vehiclemod0_.vehicle_id as vehicle_9_4_0_, vehiclemod0_.id as id1_4_0_, vehiclemod0_.id as id1_4_1_, vehiclemod0_.ccm as ccm2_4_1_, vehiclemod0_.engine_type_id as engine_t3_4_1_, vehiclemod0_.is_active as is_activ4_4_1_, vehiclemod0_.kw as kw5_4_1_, vehiclemod0_.manufacturer_id as manufact6_4_1_, vehiclemod0_.title as title7_4_1_, vehiclemod0_.vehicle_id as vehicle_9_4_1_, vehiclemod0_.year_of_manufacture as year_of_8_4_1_ from vehicle_model vehiclemod0_ where vehiclemod0_.vehicle_id=? 2019-06-23 02:04:11.049 WARN 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 1054, SQLState: 42S22 2019-06-23 02:04:11.049 ERROR 5896 --- [nio-8080-exec-1] ohengine.jdbc.spi.SqlExceptionHelper : Unknown column 'vehiclemod0_.vehicle_id' in 'field list'

Answer 1

Found a solution here: https://www.baeldung.com/jpa-many-to-many

I've been looking it a bit wrong since this is a ManyToMany relationship. My idea was to go to the "middle" table and select all vehicle_id where userId = :id and from the list of vehicle_ids to get details for each vehicle.

Here is the correct implementation that works:

@Entity(name = "user")
public class User {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String username;
private String password;
private String firstName;
private String lastName;
private boolean isActive;

@OneToMany(mappedBy = "user")
private Set<UserVehicle> userVehicles;

@Entity(name = "user_vehicle")
public class UserVehicle {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private boolean isActive;

@ManyToOne
@JoinColumn(name = "vehicle_id")
private Vehicle vehicle;

@ManyToOne
@JoinColumn(name = "user_id")
private User user;


@Entity(name = "vehicle_model")
public class Vehicle {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private Long manufacturerId;
private String title;
private int ccm;
private int kw;
private int yearOfManufacture;
private int engineTypeId;
private boolean isActive;

@OneToMany(mappedBy = "vehicle")
private Set<UserVehicle> userVehicles;

Finally, in the repository Interface I have a method like this:

public interface UserVehicleRepository extends CrudRepository<UserVehicle, Long> {

Iterable<UserVehicle> findVehicleModelsByUserId(Long userId);

The output comes out like this:

[
    {
        "id": 2,
        "vehicle": {
            "id": 2,
            "manufacturerId": 1,
            "title": "Fazer FZ1S",
            "ccm": 998,
            "kw": 110,
            "yearOfManufacture": 2008,
            "engineTypeId": 1,
            "active": true
        },
        "user": {
            "id": 2,
            "username": "sfajkovic",
            "password": "33",
            "firstName": "Ivan",
            "lastName": "Fajkovic",
            "active": true
        },
        "active": true
    }
]

The issue is not that I don't really want the user object in the result so now I need to figure that one out. And after that, I will try to map VehicleManufacturer class to get those results as well in the same response.

Answer 2

Here is the solution to do what I intentionally wanted - to search Vehicles based on the user_id in the user_vehicle table:

@Entity(name = "user_vehicle")
public class UserVehicle {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;
  private boolean isActive;
  private long userId;

  @ManyToOne
  @JoinColumn(name = "vehicle_id")
  private Vehicle vehicle;


@Entity(name = "vehicle_model")
public class Vehicle {

  @Id
  @Min(1)
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;
  private Long manufacturerId;
  private String title;
  private int ccm;
  private int kw;
  private int yearOfManufacture;
  private int engineTypeId;
  private boolean isActive;

  @OneToMany(mappedBy = "vehicle")
  private Set<UserVehicle> userVehicles;


@Repository
public interface UserVehicleRepository extends CrudRepository<UserVehicle, Long> {

  Iterable<UserVehicle> findVehicleModelsByUserId(Long userId);

The User class is actually not used at all:

@Entity(name = "user")
public class User {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;
  private String username;
  private String password;
  private String firstName;
  private String lastName;
  private boolean isActive;

This is a OneToMany relationship now and is doing what I actually wanted in the first time.

Hope it helps someone