I'm trying to implement One-to-Many relation between two tables using hibernate. Here is my code:
#Entity
public class Board
{
#Id
#Column(name = "board_id")
#GeneratedValue
private long id;
#Column
private String owner;
#Column
private String title;
#Column
private String refresh;
#Column
private Timestamp createDate;
#Column
private Timestamp modifyDate;
#OneToMany(mappedBy="board", cascade=CascadeType.ALL)
private List<Item> items;
public long getId()
{
return id;
}
public void setId(long id)
{
this.id = id;
}
public String getOwner()
{
return owner;
}
public void setOwner(String owner)
{
this.owner = owner;
}
public String getTitle()
{
return title;
}
public void setTitle(String title)
{
this.title = title;
}
public String getRefresh()
{
return refresh;
}
public void setRefresh(String refresh)
{
this.refresh = refresh;
}
public Timestamp getCreateDate()
{
return createDate;
}
public void setCreateDate(Timestamp createDate)
{
this.createDate = createDate;
}
public Timestamp getModifyDate()
{
return modifyDate;
}
public void setModifyDate(Timestamp modifyDate)
{
this.modifyDate = modifyDate;
}
public List<Item> getItems()
{
return items;
}
public void setItems(List<Item> items)
{
this.items = items;
}
}
and second table:
#Entity
public class Item
{
public enum Type
{
link,
image,
presentation;
}
public enum JavaScript
{
enable,
disable;
}
#Id
#Column
#GeneratedValue
private long id;
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "board_id")
private Board board;
#Column
private Type type;
#Column(length = 10000)
private String link;
#Column
private String image;
#Column
private String presentation;
#Column
private String time;
#Column
private JavaScript javaScript;
#Column
private String first;
#Column
private String last;
#Transient
private MultipartFile imageFile;
#Transient
private MultipartFile presentationFile;
public long getId()
{
return id;
}
public void setId(long id)
{
this.id = id;
}
public Board getBoard()
{
return board;
}
public void setBoard(Board board)
{
this.board = board;
}
public Type getType()
{
return type;
}
public void setType(Type type)
{
this.type = type;
}
public String getLink()
{
return link;
}
public void setLink(String link)
{
this.link = link;
}
public String getImage()
{
return image;
}
public void setImage(String image)
{
this.image = image;
}
public String getPresentation()
{
return presentation;
}
public void setPresentation(String presentation)
{
this.presentation = presentation;
}
public String getTime()
{
return time;
}
public void setTime(String time)
{
this.time = time;
}
public JavaScript getJavaScript()
{
return javaScript;
}
public void setJavaScript(JavaScript javaScript)
{
this.javaScript = javaScript;
}
public String getFirst()
{
return first;
}
public void setFirst(String first)
{
this.first = first;
}
public String getLast()
{
return last;
}
public void setLast(String last)
{
this.last = last;
}
public MultipartFile getImageFile()
{
return imageFile;
}
public void setImageFile(MultipartFile imageFile)
{
this.imageFile = imageFile;
}
public MultipartFile getPresentationFile()
{
return presentationFile;
}
public void setPresentationFile(MultipartFile presentationFile)
{
this.presentationFile = presentationFile;
}
}
but I can't get it working. board_id is always null in item table. Hibernate output looks strange:
Hibernate: insert into Board (board_id, createDate, modifyDate, owner, refresh, title) values (null, ?, ?, ?, ?, ?)
Hibernate: insert into Item (id, board_id, first, image, javaScript, last, link, presentation, time, type) values (null, ?, ?, ?, ?, ?, ?, ?, ?, ?)
any ideas?
To expand on the comment by #Antoniossss, you need to set the relation on both sides before persisting.
// Create owning entity first
Board board = new Board();
// Create child entities
Item item1 = new Item();
item1.setBoard(board); // set relation on Item side
board.getItems().add(item1); // set relation on Board side
Also note that it is considered good practice to initialize collection fields immediately, so that Board#getItems() never returns null.
Quick tip:
When using #GeneratedValue for an #Id field, it's best to avoid explicitly setting a value on that field.
#GeneratedValue means that either Hibernate or your database of choice will set the entity's id(either of which depends on your GenerationType), so setting an explicit value or allowing it to be publicly set possibly will result in throwing a Hibernate-specific StaleStateException.
So you should not include id in your constructor and also remove:
public void setId(long id)
{
this.id = id;
}
Related
I have a next question: while working with Hibernate 3.3.0 run into a situation when I have two tables with one-to-many relationships and I need to get the list of parents. In each entity must be filled the several fields from the parent table and a list of all children mapped in the parent. For the easiest understanding, I give an example. I have two tables with one-to-many relationships: parent is "recipients" and child is "requisites". And I have two classes whose objects are the rows of these tables. Class for the table of recipients:
#Entity
#Table(name = "recipients")
#JsonFilter(value = "recipientsFilter")
public class POJORecipient implements POJO {
private static final long serialVersionUID = 4436819032452218525L;
#Id
#Column
private long id;
#Version
#Column
private long version;
#Column(name = "client_id")
private long clientId;
#Column
private String inn;
#Column
private String name;
#Column(name = "rcpt_country_code")
private String rcptCountryCode;
#Column(name = "rcpt_passp_ser")
private String rcptPasspSer;
#Column(name = "rcpt_passp_num")
private String rcptPasspNum;
#OneToMany(mappedBy = "recipient", fetch = FetchType.LAZY)
#JsonManagedReference
private Set<POJORequisite> requisites = new HashSet<>();
public POJORecipient(){}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public long getVersion() {
return version;
}
public void setVersion(long version) {
this.version = version;
}
public long getClientId() {
return clientId;
}
public void setClientId(long clientId) {
this.clientId = clientId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getInn() {
return inn;
}
public void setInn(String inn) {
this.inn = inn;
}
public String getRcptCountryCode() {
return rcptCountryCode;
}
public void setRcptCountryCode(String rcptCountryCode) {
this.rcptCountryCode = rcptCountryCode;
}
public String getRcptPasspSer() {
return rcptPasspSer;
}
public void setRcptPasspSer(String rcptPasspSer) {
this.rcptPasspSer = rcptPasspSer;
}
public String getRcptPasspNum() {
return rcptPasspNum;
}
public void setRcptPasspNum(String rcptPasspNum) {
this.rcptPasspNum = rcptPasspNum;
}
public Set<POJORequisite> getRequisites() {
return requisites;
}
public void setRequisites(Set<POJORequisite> requisites) {
this.requisites = requisites;
}
}
and for requisites table:
#Entity
#Table(name = "requisites")
public class POJORequisite implements POJO {
private static final long serialVersionUID = -35864567359179960L;
#Id
#Column
private long id;
#Version
#Column
private long version;
#Column
private String bic;
#Column
private String bill;
#Column
private String comments;
#Column
private String note;
#ManyToOne
#JoinColumn(name = "recipient_id")
#JsonBackReference
private POJORecipient recipient;
public POJORequisite(){}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public long getVersion() {
return version;
}
public void setVersion(long version) {
this.version = version;
}
public String getBic() {
return bic;
}
public void setBic(String bic) {
this.bic = bic;
}
public String getBill() {
return bill;
}
public void setBill(String bill) {
this.bill = bill;
}
public String getComments() {
return comments;
}
public void setComments(String comments) {
this.comments = comments;
}
public String getNote() {
return note;
}
public void setNote(String note) {
this.note = note;
}
public POJORecipient getRecipient() {
return recipient;
}
public void setRecipient(POJORecipient recipient) {
this.recipient = recipient;
}
}
So, I want to select from the recipients only names and all mapped requisites. Consequently, after the selection, I will have a list of POJORecipient objects and in each object filled only the field "name" and set of POJORequisite objects.
As answer of my question I want to discover one of next: how can I do that with help HQL or Criteria API (the second variant is preferable), or understand it is impossible in Hibernate at all, or that this possibility appeared in later versions (also preferably with example). I'm trying to resolve this question for several months now and will be immensely grateful for any help. All clarifications and advices also will be so helpful. Thanks in advance!!!
MenuModel
#Entity
#Table(name="M_MENU", uniqueConstraints={#UniqueConstraint(columnNames={"NAME"})})
public class MenuModel {
private Integer id;
private String code;
private String name;
private String controller;
private Integer parent_id;
#Id
#Column(name="ID")
#GeneratedValue(strategy=GenerationType.TABLE, generator="M_MENU")
#TableGenerator(name="M_MENU", table="M_SEQUENCE",
pkColumnName="SEQUENCE_NAME", pkColumnValue="M_MENU_ID",
valueColumnName="SEQUENCE_VALUE", allocationSize=1, initialValue=0
)
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Column(name="CODE")
public String getCode() {
return code;
}
public void setCode(String kode) {
this.code = kode;
}
#Column(name="NAME")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Column(name="CONTROLLER")
public String getController() {
return controller;
}
public void setController(String controller) {
this.controller = controller;
}
#Column(name="PARENT_ID")
public Integer getParent_id() {
return parent_id;
}
public void setParent_id(Integer parent_id) {
this.parent_id = parent_id;
}
}
UserAccessModel
#Entity
#Table(name="M_USER_ACCESS")
public class UserAccessModel {
private Integer id;
//join table role
private Integer idRole;
private RoleModel roleModel;
//join table menu
private Integer idMenu;
private MenuModel menuModel;
#Id
#Column(name="ID")
#GeneratedValue(strategy=GenerationType.TABLE, generator="M_USER_ACCESS")
#TableGenerator(name="M_USER_ACCESS", table="M_SEQUENCE",
pkColumnName="SEQUENCE_NAME", pkColumnValue="M_USER_ACCESS_ID",
valueColumnName="SEQUENCE_VALUE", allocationSize=1, initialValue=0
)
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Column(name="ID_ROLE")
public Integer getIdRole() {
return idRole;
}
public void setIdRole(Integer idRole) {
this.idRole = idRole;
}
#ManyToOne
#JoinColumn(name="ID_ROLE", nullable=true, updatable=false, insertable=false)
public RoleModel getRoleModel() {
return roleModel;
}
public void setRoleModel(RoleModel roleModel) {
this.roleModel = roleModel;
}
#Column(name="ID_MENU")
public Integer getIdMenu() {
return idMenu;
}
public void setIdMenu(Integer idMenu) {
this.idMenu = idMenu;
}
#ManyToOne
#JoinColumn(name="ID_MENU", nullable=true, updatable=false, insertable=false)
public MenuModel getMenuModel() {
return menuModel;
}
public void setMenuModel(MenuModel menuModel) {
this.menuModel = menuModel;
}
}
MenuDaoImpl
#Override
public List<MenuModel> searchByRole(Integer idRole) {
// TODO Auto-generated method stub
Session session = this.sessionFactory.getCurrentSession();
List<MenuModel> menuModelListRole = new ArrayList<MenuModel>();
Criteria userAccessCriteria = session.createCriteria(UserAccessModel.class,"UA");
Criteria menuCriteria = userAccessCriteria.createCriteria("menuModel","M");
userAccessCriteria.add(Restrictions.eq("idRole", ""+idRole+""));
ProjectionList properties = Projections.projectionList();
properties.add(Projections.property("M.id"));
properties.add(Projections.property("M.name"));
properties.add(Projections.property("M.code"));
properties.add(Projections.property("M.controller"));
properties.add(Projections.property("M.parent_id"));
menuCriteria.setProjection(properties);
menuModelListRole = menuCriteria.list();
return menuModelListRole;
}
I want to get result of the following sql:
select M.ID ID, M.NAME NAME, M.CODE CODE, M.CONTROLLER CONTROLLER,
M.PARENT_ID PARENT from M_MENU M join M_USER_ACCESS UA on UA.ID_MENU
= M.ID where UA.ID_ROLE="+idRole+"
I got error in method searchByRole in menuModelListRole = menuCriteria.list();. How can i resolve the problem?
Here private Integer idRole; is of Integer type, but you are passing idRole as String in Restrictions.eq("idRole", ""+idRole+""). SO you are getting java.lang.String cannot be cast to java.lang.Integer in Spring
Changing you restriction value from Restrictions.eq("idRole", ""+idRole+"") to Restrictions.eq("idRole", idRole) should solve your problem.
I have three tables :
1. org,
2. product_info
3. service_info.
And, table product_info is mapping table service_info ManyToMany,
means,many products mapping many services.
While,table org is mapping table product_info OneToMany,
means,one org have many products.
When I initialize my web
I want to view the org table's column. How to do ?
Under classes are the persistent classes for three tables.
ProductService class:
`
#Entity
#Table(name="product_service")
#Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class ProductService implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private ServiceInfo serviceInfo;//this is the service table
private String parammapping;
private ProductInfo productInfo;//this is the product table
// Constructors
/** default constructor */
public ProductService() {
}
/** minimal constructor */
public ProductService(String id) {
this.id = id;
}
// Property accessors
#Id
#Column(name="ID", unique=true, nullable=false, length=50)
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="SERVICEID")
public ServiceInfo getServiceInfo() {
return this.serviceInfo;
}
public void setServiceInfo(ServiceInfo serviceInfo) {
this.serviceInfo = serviceInfo;
}
#Column(name="PARAMMAPPING", length=1000)
public String getParammapping() {
return parammapping;
}
public void setParammapping(String parammapping) {
this.parammapping = parammapping;
}
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="PRODUCTID")
public ProductInfo getProductInfo() {
return this.productInfo;
}
public void setProductInfo(ProductInfo productInfo) {
this.productInfo = productInfo;
}
}`
baseOrg class:
#Entity
#Table(name="base_org")
#Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class BaseOrg implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String code;
private String name;
private List<BaseRuleEngineLog> serviceUsedLogs = new ArrayList<BaseRuleEngineLog>(0);
private List<ProductInfo> productInfos = new ArrayList<ProductInfo>(0);
private List<BaseCreditQuery> baseCreditQueries = new ArrayList<BaseCreditQuery>(0);
// Constructors
/** default constructor */
public BaseOrg() {
}
/** minimal constructor */
public BaseOrg(String id) {
this.id = id;
}
#Id
#Column(name="ID", unique=true, nullable=false, length=50)
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
#Column(name="CODE", length=50)
public String getCode() {
return this.code;
}
public void setCode(String code) {
this.code = code;
}
#Column(name="NAME", length=200)
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="baseOrg")
public List<BaseRuleEngineLog> getServiceUsedLogs() {
return this.serviceUsedLogs;
}
public void setServiceUsedLogs(List<BaseRuleEngineLog> serviceUsedLogs) {
this.serviceUsedLogs = serviceUsedLogs;
}
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="baseOrg")
public List<ProductInfo> getProductInfos() {
return this.productInfos;
}
public void setProductInfos(List<ProductInfo> productInfos) {
this.productInfos = productInfos;
}
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="baseOrg")
public List<BaseCreditQuery> getBaseCreditQueries() {
return this.baseCreditQueries;
}
public void setBaseCreditQueries(List<BaseCreditQuery> baseCreditQueries) {
this.baseCreditQueries = baseCreditQueries;
}
}
productInfo class:
#Entity
#Table(name="product_info")
#Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class ProductInfo implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private BaseOrg baseOrg;//baseOrg table
private String code;
private String name;
private String orgcode;
private List<ProductService> productServices = new ArrayList<ProductService>(0);
// Constructors
/** default constructor */
public ProductInfo() {
}
/** minimal constructor */
public ProductInfo(String id) {
this.id = id;
}
// Property accessors
#Id
#Column(name="ID", unique=true, nullable=false, length=50)
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="ORGID")
public BaseOrg getBaseOrg() {
return this.baseOrg;
}
public void setBaseOrg(BaseOrg baseOrg) {
this.baseOrg = baseOrg;
}
#Column(name="CODE", length=100)
public String getCode() {
return this.code;
}
public void setCode(String code) {
this.code = code;
}
#Column(name="NAME", length=100)
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
#Column(name="ORGCODE", length=100)
public String getOrgcode() {
return this.orgcode;
}
public void setOrgcode(String orgcode) {
this.orgcode = orgcode;
}
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="productInfo")
public List<ProductService> getProductServices() {
return this.productServices;
}
public void setProductServices(List<ProductService> productServices) {
this.productServices = productServices;
}
}
serviceInfo class
#Entity
#Table(name="service_info")
#Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
public class ServiceInfo implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String name;
private String code;
private List<ProductService> productServices = new ArrayList<ProductService>(0);
// Constructors
/** default constructor */
public ServiceInfo() {
}
/** minimal constructor */
public ServiceInfo(String id) {
this.id = id;
}
// Property accessors
#Id
#Column(name="ID", unique=true, nullable=false, length=50)
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
#Column(name="NAME", length=100)
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
#Column(name="CODE", length=100)
public String getCode() {
return this.code;
}
public void setCode(String code) {
this.code = code;
}
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="serviceInfo")
public List<ProductService> getProductServices() {
return this.productServices;
}
public void setProductServices(List<ProductService> productServices) {
this.productServices = productServices;
}
}
product_service table
Thank you for forgiving my poor English,this is my first time questioning on Stack Overflow.
OK,I resolve it.
i found its so sample,lol.
Because,most criteria have been packaged.At the first time ,I want to use the HQL to resolve it,but in vain.I just add this sentences,and getted it.
enter image description here
I have the following code that is not working properly.
testprovincia exist on data base and the partidos variable is a list that I am sure is not empty but is never persisted too.
mgr = getPersistenceManager();
Query query = mgr.newQuery(Provincia.class);
query.setFilter("name == nameParam");
query.declareParameters("String nameParam");
List<Provincia> results = (List<Provincia>) query.execute("testprovincia");
Provincia prov = results.get(0);
insertPartidos(partidos);
prov.setPartidos(partidos);
mgr.makePersistent(prov);
query.closeAll();
mgr.close();
InsertPartidos method:
private void insertPartidos(List<Partido> partidos){
for (Partido partido : partidos) {
log.info(partido.getName());
mgr.makePersistent(partido);
}
}
The question is why I never see the list I added to prov variable on the database? Is allways empty.
Here are my classes:
#PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Provincia {
public Provincia(String name) {
super();
this.name = name;
}
#PrimaryKey
#Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key id;
#Persistent
private String name;
#Persistent(mappedBy = "provincia")
#Order(extensions = #Extension(vendorName="datanucleus",key="list-ordering", value="name asc"))
private List<Partido> partidos;
public Key getId() {
return id;
}
public void setId(Key id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Partido> getPartidos() {
return partidos;
}
public void setPartidos(List<Partido> partidos) {
this.partidos = partidos;
}
}
#PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Partido {
#PrimaryKey
#Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key id;
#Persistent
private String name;
#Persistent
private Provincia provincia;
public Partido(){
}
public Partido(Key id) {
super();
this.id = id;
}
public Partido(Key id, String name, Provincia prov) {
super();
this.id = id;
this.name = name;
this.provincia = prov;
}
public Partido(String name, Provincia prov) {
super();
this.name = name;
this.provincia = prov;
}
public Key getId() {
return id;
}
public void setId(Key id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Provincia getProvincia() {
return provincia;
}
public void setProvincia(Provincia provincia) {
this.provincia = provincia;
}
}
Maybe using the other way of updating. If testprovincia already exists, using the method described here might do the trick for you. Instead of using makepersistent, grab your data with the persistence manager and straight update it.
That or use standard datastore's db (or ndb) puts, as explained here? Do you REALLY need the JDO?
I have model. there is this part:
model was mapped by jpa annotations.Everywhere I use fetchType = EAGER. If I load vacancy from database, I have 2 duplicates status_for_vacancy objects.
I use property hbm2ddl.auto = update.
If I make new schema of database and fill data, I haven't duplicates status_for_vacancy objects.
It really?
code:
vacancy:
#Entity
#Table(name = "vacancy")
#XmlRootElement(name="vacancy")
public class Vacancy {
private List<VacancyStatus> statusList = new LinkedList<VacancyStatus>();
#OneToMany(mappedBy = "vacancy", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
public List<VacancyStatus> getStatusList() {
return statusList;
}
public void setStatusList(List<VacancyStatus> statusList) {
this.statusList = statusList;
}
}
status_for_vacancy:
#Entity
#Table(name = "status_for_vacancy")
public class StatusForVacancy extends AbstractStatus {
public StatusForVacancy() {
super();
}
public StatusForVacancy(Integer id, String name) {
super(id, name);
}
}
#MappedSuperclass
#XmlRootElement
public abstract class AbstractStatus {
private Integer id;
private String name;
public AbstractStatus() {
super();
}
public AbstractStatus(String name) {
super();
this.name = name;
}
public AbstractStatus(Integer id, String name) {
super();
this.id = id;
this.name = name;
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column (name ="id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Column(name = "name")
#NotEmpty
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
vacancy_status:
#Entity
#Table(name = "vacancy_status")
public class VacancyStatus extends AbstractHistoryStatus {
private Vacancy vacancy;
private StatusForVacancy status;
public VacancyStatus() {
super();
}
public VacancyStatus(Integer id, User author, Date date,
Vacancy vacancy, StatusForVacancy status) {
super(id, author, date);
this.vacancy = vacancy;
this.status = status;
}
#ManyToOne
#JoinColumn(name = "vacancy_id")
public Vacancy getVacancy() {
return vacancy;
}
public void setVacancy(Vacancy vacancy) {
this.vacancy = vacancy;
}
#ManyToOne
#JoinColumn(name = "status_id")
public StatusForVacancy getStatus() {
return status;
}
public void setStatus(StatusForVacancy status) {
this.status = status;
}
}
#MappedSuperclass
public abstract class AbstractHistoryStatus {
private Integer id;
private User author;
private Date date;
public AbstractHistoryStatus() {
}
public AbstractHistoryStatus(Integer id, User author, Date date) {
super();
this.id = id;
this.author = author;
this.date = date;
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#ManyToOne
public User getAuthor() {
return author;
}
public void setAuthor(User author) {
this.author = author;
}
#Column(name="creation_date")
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
}
It is all mapping code for these entities.
in debugger:
both id==500 ==> hibernate understand, that it is same objects.
I try add all data from old database to new database - I get old error(
I fix cause of appearance of this problem. It appearances if I add record to note table:
I highly recommend you write equals() and hashCode() methods. The standard equals()/hashCode() implement referential equality (do 2 objects reference the same memory location). So if hibernate has 2 of the 'same' object in memory, but they don't reference the same memory location then you will see the object show up twice. But if you implement equals() based on primary key being equal, then even if there are two copies of the same object in memory, Hibernate won't give you duplicates.
See the JPA spec:
2.4 Primary Keys and Entity Identity
Every entity must have a primary key. ... The value of its primary key
uniquely identifies an entity instance within a persistence context
and to EntityManager operations
Also see this SO post.