java Hibernate:无法删除|删除分离的实例
我正在制作一个简单的api,在这里我可以存储图像并对其执行crud功能。为了与数据库通信,我使用Hibernate。虽然获取数据进展顺利,但我无法添加或删除数据。这将导致add出现此异常
org.hibernate.exception.GenericJDBCException: could not execute statement
此例外情况为删除
Removing a detached instance com.mycompany.server.model.Image#0
我不知道它为什么做不到这项工作。它以前是有效的,我没有做任何改变。希望你能找到问题所在。如果这些信息还不够,只需评论你想看到的内容即可
这是您的模型:
@Entity
@Table(name = "image")
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@NamedQueries({
@NamedQuery(name = "Image.findAll", query = "SELECT i FROM Image i")
, @NamedQuery(name = "Image.findByImageId", query = "SELECT i FROM Image i WHERE i.imageId = :imageId")
, @NamedQuery(name = "Image.findByContenttype", query = "SELECT i FROM Image i WHERE i.contenttype = :contenttype")
, @NamedQuery(name = "Image.findByName", query = "SELECT i FROM Image i WHERE i.name = :name")
, @NamedQuery(name = "Image.findByDescription", query = "SELECT i FROM Image i WHERE i.description = :description")})
public class Image implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@XmlElement(nillable=true)
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Basic(optional = false)
@NotNull
@Column(name = "image_id")
private Integer imageId;
@Basic(optional = false)
@NotNull
@Lob
@Size(min = 1, max = 16777215)
@Column(name = "content")
private String content;
@Basic(optional = false)
@Size(min = 1, max = 45)
@Column(name = "contenttype")
private String contenttype;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 45)
@Column(name = "name")
private String name;
@Size(max = 45)
@Column(name = "description")
private String description;
public Image() {
}
public Image(Integer imageId) {
this.imageId = imageId;
}
public Image(Integer imageId, String content, String contenttype, String name) {
this.imageId = imageId;
this.content = content;
this.contenttype = contenttype;
this.name = name;
}
public Integer getImageId() {
return imageId;
}
public void setImageId(Integer imageId) {
this.imageId = imageId;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getContenttype() {
return contenttype;
}
public void setContenttype(String contenttype) {
this.contenttype = contenttype;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
@Override
public int hashCode() {
int hash = 0;
hash += (imageId != null ? imageId.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Image)) {
return false;
}
Image other = (Image) object;
if ((this.imageId == null && other.imageId != null) || (this.imageId != null && !this.imageId.equals(other.imageId))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.mycompany.server.model.Image[ imageId=" + imageId + " ]";
}
}
以及服务的实施:
public class ImageRepositoryServiceImpl implements ImageRepositoryService {
private EntityManagerFactory entityManagerFactory;
private static ImageRepositoryServiceImpl instance;
private ImageRepositoryServiceImpl() {
entityManagerFactory = Persistence.createEntityManagerFactory("com.mycompany_server_war_1.0-SNAPSHOTPU");
}
static {
instance = new ImageRepositoryServiceImpl();
}
private EntityManager getEntityManager() {
return entityManagerFactory.createEntityManager();
}
public static ImageRepositoryService getInstance() {
return instance;
}
@Override
public List<Image> getAllImages() {
EntityManager em = entityManagerFactory.createEntityManager();
List<Image> images = em.createNamedQuery("Image.findAll", Image.class).getResultList();
em.close();
return images;
}
@Override
public Image getImageFromId(int imageId) {
EntityManager em = entityManagerFactory.createEntityManager();
Image image = em.find(Image.class, imageId);
em.close();
return image;
}
@Override
public boolean addImage(Image image) {
try{
EntityManager em = entityManagerFactory.createEntityManager();
em.getTransaction().begin();
em.persist(image);
em.getTransaction().commit();
em.close();
return true;
}catch(Exception e){
return false;
}
}
@Override
public boolean editImage(Image image) {
throw new UnsupportedOperationException("Not supported yet. edit"); //To change body of generated methods, choose Tools | Templates.
}
@Override
public boolean DeleteImage(Image image) {
try{
EntityManager em = entityManagerFactory.createEntityManager();
em.remove(image);
return true;
}catch(Exception e){
return false;
}
}
}
编辑:
我解决了这个问题。显然image_id
不是自动激励的。现在我改为人工智能,它工作得很好。但删除仍不起作用:'(
# 1 楼答案
我在此代码中看到了哪些问题:
也许这些笔记会对你有所帮助