Spring MVC : storing data with ManyToOne / OneToMany relationships

Question

I am using Spring-mvc & Spring-data-jpa in my project. I have these two entities

Location.java:

@Entity
@Table(name = "location")
@JsonIgnoreProperties(ignoreUnknown = true)
public class Location {
    @Id
    @GeneratedValue
    private int id;

    // other attributes...

    @ManyToOne(optional=true)
    @JoinColumn(name ="user")
    @JsonBackReference
    private User user;

    @ManyToOne(optional=true)
    @JoinColumn(name ="client")  
    @JsonBackReference
    private Client client;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    // getters & setters

}

User.java:

@Entity
@Table(name = "users")
@JsonIgnoreProperties(ignoreUnknown = true)
public class User {

    @Id
    @GeneratedValue
    private int uid;

    // other attributes...

    @OneToMany(mappedBy="user")
    @JsonManagedReference
    private List<Location> locations;

    // getters & setters...

    @JsonIgnore
    public List<Location> getLocations() {
        return locations;
    }

    public void setLocations(List<Location> locations) {
        this.locations = locations;
    }

}

What i want to do is to add a new Location and link it to an existing User. For both entitie there is a Repository and a Service. LocationRepository.java:

public interface LocationRepository extends CrudRepository<Location, Integer> {

    List<Location> findAll();

    //....

}

LocationService.java

@Service
public class LocationService {

    @Autowired
    private LocationRepository locationRepository;


    public List<Location> findAll() {
        return locationRepository.findAll();
    }

    public void save(Location location) {
        locationRepository.save(location);
    }

    @Secured("ROLE_ADMIN")
    public void delete(int locationId) {
        locationRepository.delete(locationId);
    }
}

ApiController.java

@Controller
@RequestMapping(value = "/rest/api")
public class ApiController {

    @Autowired
    UserService userService;
    @Autowired
    LocationService locationService;

    // Storing a new location

    @RequestMapping(value = "/locations/checkin", method = RequestMethod.POST, produces = "application/json")
    public ResponseEntity<?> checkin(@ModelAttribute("location") Location location) {
        locationService.save(location);
        List<Location> locationslist = locationService.findAll();
        return new ResponseEntity<List<Location>>(locationslist, HttpStatus.OK);
    }

}

All seems fine till now. I am using this Restfull service for an Android client, all i have to do is to custruct a new Location object and send it via a POST request to the right URI.

This is the structure of the object :

{
    "id":1,
    ....,
    ....,
    "user":{
            "uid":1,
            "attr1":"value1",
            "attr2":"value2",
             .....
            }
}

Problem : I am always getting a (org.hibernate.exception.SQLGrammarException) error (Caused by: org.postgresql.util.PSQLException: ERROR: syntax error at or near "user")

What i am doing wrong ? and what is the best approach to store my location ?

Answer 1

The exception states that an invalid SQL statement is generated

org.postgresql.util.PSQLException: ERROR: syntax error at or near "user" 

Try to rename the column 'user' to something 'user' is a reserved word in Postgres, so instead of

@JoinColumn(name ="user")

use something like

@JoinColumn(name ="user_location")