Inject a repository into an entity

Question

I try to inject a repository into an entity, because in a special case I need to create the entity from name (this is what I get from JSON through jackson). This entity is quite simple:

+----+------+
| id | name |
+----+------+

The Role entity should have the RoleRepository injected. I currently try:

@Entity
@Component
@Table(name = "roles" )
public class Role {

@Resource
@Transient
private RoleRepository roleRepository;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
private Integer roleId;

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

@ManyToMany(mappedBy = "roles")
List<SystemUser> systemUsers;

public Role() { }

@JsonCreator
public Role(String roleString) {
    Role role = roleRepository.findByName(roleString).get(0); /*** HERE ***/
    setRoleId(role.getRoleId());
    setName(role.getName());
}

public Role(Integer id, String name) {
    this.roleId = id;
    this.name = name;
}

public Integer getRoleId() {
    return roleId;
}

public void setRoleId(Integer roleId) {
    this.roleId = roleId;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String toString() {
    if(getName() != null) {
        return WordUtils.capitalize(getName().toLowerCase());
    } else {
        return "";
    }
}
}

Current issue: roleRepository is null at the line I marked with "HERE". So I get a NullPointer and do not fetch the Role entity I wanted to have.

Answer 1

The reason what you are trying to do does not work, is that Entities are not managed by Spring, but by your JPA provider. There for, injection of dependencies will not occur.

In order to make dependency injection work on non Spring-managed classes, you need to use @Configurable along with a Java agent.

Check out this and this.