休眠：删除实体在一个一对多的关系

Question

我有一个以下错误：

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`spindledb`.`section`, CONSTRAINT `FK_ftoru9cp83n512p9is8x3vo53` FOREIGN KEY (`scenario_id`) REFERENCES `scenario` (`scenario_id`)) 

这里是我的课：

场景：

@Entity 
@Table(name = "scenario") 
public class Scenario { 

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Column(name = "scenario_id") 
private int id; 

@Column(name = "title", nullable = false) 
private String title; 

@NotNull 
@DateTimeFormat(pattern = "dd/MM/yyyy") 
@Column(name = "creation_date", nullable = false) 
@Type(type = "org.jadira.usertype.dateandtime.joda.PersistentLocalDate") 
private LocalDate creationDate; 

@ManyToOne 
@LazyCollection(LazyCollectionOption.FALSE) 
@JoinColumn(name = "id", nullable = false) 
private User user; 

@OneToMany(mappedBy = "scenario", orphanRemoval = true) 
@LazyCollection(LazyCollectionOption.FALSE) 
private Set<Plot> plotList = new HashSet<Plot>(); 

@OneToMany(mappedBy = "scenario", orphanRemoval = true) 
@LazyCollection(LazyCollectionOption.FALSE) 
private Set<Character> characterList = new HashSet<Character>(); 

@OneToMany(mappedBy = "scenario", cascade=CascadeType.ALL, orphanRemoval = true) 
@LazyCollection(LazyCollectionOption.FALSE) 
@OrderBy("sequence ASC") 
private Set<Section> sectionList = new HashSet<Section>(); 

科：

@Entity 
@Table(name = "section") 
public class Section { 

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Column(name = "section_id") 
private int id; 

@Size(min = 4, max = 50) 
@NotNull 
@Column(name = "name") 
private String name; 

@NotNull 
@Column(name = "type") 
private String type = SectionType.TEXT.getSectionType(); 

@Column(name = "visibility") 
private boolean visibility; 

@NotNull 
@Column(name = "sequence") 
private int sequence; 

@ManyToOne (cascade=CascadeType.ALL) 
@LazyCollection(LazyCollectionOption.FALSE) 
@JoinColumn(name = "scenario_id", nullable = false) 
private Scenario scenario; 

控制器：

@RequestMapping(value = { "/delete-{id}-scenario" }, method = RequestMethod.GET) 
public String deleteScenario(@PathVariable int id) { 

    scenarioService.deleteScenarioById(id); 
    return "redirect:/home"; 
} 

方案服务：

@Service("scenarioService") 
@Transactional 
public class ScenarioServiceImpl implements ScenarioService { 

@Autowired 
private ScenarioDao dao; 

@Override 
public Scenario findById(int id) { 
    return dao.findById(id); 
} 

@Override 
public void saveScenario(Scenario scenario) { 
    dao.saveScenario(scenario); 

} 

public void updateScenario(Scenario scenario) { 
    Scenario entity = dao.findById(scenario.getId()); 
    if(entity!=null){ 
     entity.setTitle(scenario.getTitle()); 
     entity.setCreationDate(scenario.getCreationDate());    
    } 
} 

@Override 
public void deleteScenarioById(int id) { 
    dao.deleteScenarioById(id); 

} 

道

@Repository("scenarioDao") 
public class ScenarioDaoImpl extends AbstractDao<Integer, Scenario> implements ScenarioDao { 

@Override 
public Scenario findById(int id) { 
    return getByKey(id); 
} 

@Override 
public void saveScenario(Scenario scenario) { 
    persist(scenario); 

} 

@Override 
public void deleteScenarioById(int id) { 

    Query query = getSession().createSQLQuery("delete from scenario where id = :id"); 
    query.setString("id", ""+id); 
    query.executeUpdate(); 
} 

我明白，问题是，有可能是不能没有的情况存在的部分。但是现在数据库中的部分表是空的，我仍然无法删除Scenario。感谢您的建议

Answer 1

使用cascade=CascadeType.ALL与class Scenario所有@ManyToOne的关系，因为如果你打算从数据库中删除任何方案它决不能引用数据的基础上任何地方。

另一种方法是删除。

Serializable id = new Long(1); //your id 
Object persistentInstance = session.load(Scenario.class, id); 
if (persistentInstance != null) { 
    session.delete(persistentInstance); 
} 

Answer 2

通过Query删除的实体将绕过您通过注释把任何级联设置。

我建议先找到实体的ID，然后删除实体对象：

Object scenario = session.load(Scenario.class, id); 
if (scenario != null) { 
    session.delete(scenario); 
}