As the question says, I would like to know the easiest way to perform Data Binding to regular (non JavaFX) properties of JPA entities.
I was thinking there is probably some way to use the same binding functions if you make your entity class implement some interface for change listeners or something of the sort.
Here is an example of a JPA entity with property changed listeners.
#Entity
public class Ticket {
#Id
#GeneratedValue()
private int id;
#ManyToOne()
private EntryGate entryGate;
#ManyToOne()
private ExitGate exitGate;
#Transient
private PropertyChangeSupport changeSupport = new PropertyChangeSupport(this);
public Ticket() {
}
public Ticket(EntryGate owner) {
this();
this.entryGate = owner;
}
public void addListener(PropertyChangeListener listener) {
changeSupport.addPropertyChangeListener(listener);
}
public void removeListener(PropertyChangeListener listener) {
changeSupport.removePropertyChangeListener(listener);
}
public int getId() {
return id;
}
public EntryGate getEntryGate() {
return entryGate;
}
public void setEntryGate(EntryGate entryGate) {
EntryGate oldGate = this.entryGate;
this.entryGate = entryGate;
changeSupport.firePropertyChange("entryGate", oldGate, this.entryGate);
}
public ExitGate getExitGate() {
return exitGate;
}
public void setExitGate(ExitGate exitGate) {
ExitGate oldGate = this.exitGate;
this.exitGate = exitGate;
changeSupport.firePropertyChange("exitGate", oldGate, this.exitGate);
}
}
Here is an example of a JavaFX property binding.
this.idLabel.textProperty().bind(this.ticket.idProperty().asString());
Obviously I can't replace my JPA properties with SimpleXXXProperty... because they are entities participating in object relational mapping.
Related
I have the following class structure:
public abstract class Creature{
private String name;
//strategy pattern composition
private SkillInterface skill;
}
public interface SkillInterface {
void attack();
}
public class NoSkill implements SkillInterface {
#Override
public void attack() {
//statements
}
}
My goal is to persist Creature objects at one table in database. Subclasses of SkillInterface are without any fields. As they determine the behaviour, I want to convert selected SkillInterface class name to a String, as I only need to persist the classname of the current skill strategy of creature, with a String like skill.getClass().getSimpleName(). I tried to implement it with #Converter annotation, using AttributeConverter class to convert SkillInterface to String and save, but always had mapping exceptions. I want to be able to save it as String and retrieve as SkillInterface object.
But how can I implement it with Hibernate? Or do I have a design mistake?
Ok looks like I have found a basic solution that can be used to persist Strategy Pattern interfaces implementations. I used a #Converter annotation and a AttributeConverter class to convert strategy class names to column while saving to database and cast the retrieved String back to strategy class as following:
#Entity
public class Creature {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Convert(converter = SkillConverter.class)
private SkillInterface skill;
}
public class SkillConverter implements AttributeConverter<SkillInterface,String> {
#Override
public String convertToDatabaseColumn(SkillInterface skill) {
return skill.getClass().getSimpleName().toLowerCase();
}
#Override
public SkillInterface convertToEntityAttribute(String dbData) {
//works as a factory
if (dbData.equals("noskill")) {
return new NoSkill();
} else if (dbData.equals("axe")) {
return new Axe();
}
return null;
}
}
public interface SkillInterface {
public String getSkill();
void attack();
}
public class NoSkill implements SkillInterface{
public String getSkill() {
return getClass().getSimpleName();
}
#Override
public void attack() {
//strategy statements
}
}
You can use a proxy field to this for you like below:
abstract class Creature {
#Column
private String name;
// strategy pattern composition
private SkillInterface skill;
#Column
private String skillName;
public String getSkillName() {
return skill.getClass().getSimpleName();
}
public void setSkillName(String skillName) {
//ignore
}
}
I've been using Spring Data for saving entities to the mongo DB and my code at the moment looks like this:
I have a repo class:
public interface LogRepo extends MongoRepository<Log, String> {
}
and I have an Entity Log which looks like this:
#Document(
collection = "logs"
)
public class Log {
#Id
private String id;
private String jsonMessage;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getJsonMessage() {
return jsonMessage;
}
public void setJsonMessage(String jsonMessage) {
this.jsonMessage = jsonMessage;
}
}
and this work well for me, however this approach works only for the case if I want to save Log entities to "logs" collection. However it would be very nice for me to be able to save Log entity to different collections depending on the context. I mean it would be nice to define collection name in the runtime. Is it possible somehow?
Thanks, cheers
Try to use inheritance and define appropriate collection names in such way. May give you possibility to save in different collections but you will be still not able to specify dynamically collection names and resp. their amount at runtime.
#Document(
collection = "logs"
)
public class Log {
#Id
private String id;
private String jsonMessage;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getJsonMessage() {
return jsonMessage;
}
public void setJsonMessage(String jsonMessage) {
this.jsonMessage = jsonMessage;
}
}
#Document(
collection = "log_child"
)
public class LogChild extends Log{}
With the MongoOperations save method you can choose which class to use and
based on the class it will choose the appropriate collection.
#Document(collection = "collection_#{T(com.github.your_project.DBUtils).getCollectionName()}")
public Class Collection
You can change the name in real time using a static getter
#UtilityClass
public class DBUtils {
private String collectionName;
public String getCollectionName() {
return collectionName;
}
public void setCollectionName(String collectionName) {
DBUtils.collectionName = collectionName;
}
}
I am pretty new in Spring Data and I have to write what in the official documentation seems to be called Query creation from method names, here the reference:https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#repositories.query-methods.query-creation
As you can see in the previous example show the creation of a query by the definition of a method name, for example:
List<Person> findByEmailAddressAndLastname(EmailAddress emailAddress, String lastname);
that I think return a list of Person object that have a specific email affress and a specific lastname.
So I am trying to do the same thing in my project that use Hibernate as JPA provider.
In my project I have this Twb1012Regione entity class that map the anagrafiche.TWB1012_REGIONE on the database:
#Entity
#Table(name="anagrafiche.TWB1012_REGIONE")
#NamedQuery(name="Twb1012Regione.findAll", query="SELECT t FROM Twb1012Regione t")
public class Twb1012Regione implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name="COD_REG")
private String codReg;
#Column(name="COD_ARE_GEO")
private String codAreGeo;
#Column(name="COD_CIT")
private String codCit;
#Column(name="COD_IST")
private int codIst;
#Column(name="COD_PGM_ULT_MOV")
private String codPgmUltMov;
#Column(name="COD_UTE_ULT_MOV")
private String codUteUltMov;
#Temporal(TemporalType.TIMESTAMP)
#Column(name="DAT_ORA_ULT_MOV")
private Date datOraUltMov;
#Column(name="DES_REG")
private String desReg;
//bi-directional many-to-one association to Tpg1029Provnuoist
#OneToMany(mappedBy="twb1012Regione")
private List<Tpg1029Provnuoist> tpg1029Provnuoists;
//bi-directional many-to-one association to Twb1013Provincia
#OneToMany(mappedBy="twb1012Regione")
private List<Twb1013Provincia> twb1013Provincias;
public Twb1012Regione() {
}
public String getCodReg() {
return this.codReg;
}
public void setCodReg(String codReg) {
this.codReg = codReg;
}
public String getCodAreGeo() {
return this.codAreGeo;
}
public void setCodAreGeo(String codAreGeo) {
this.codAreGeo = codAreGeo;
}
public String getCodCit() {
return this.codCit;
}
public void setCodCit(String codCit) {
this.codCit = codCit;
}
public int getCodIst() {
return this.codIst;
}
public void setCodIst(int codIst) {
this.codIst = codIst;
}
public String getCodPgmUltMov() {
return this.codPgmUltMov;
}
public void setCodPgmUltMov(String codPgmUltMov) {
this.codPgmUltMov = codPgmUltMov;
}
public String getCodUteUltMov() {
return this.codUteUltMov;
}
public void setCodUteUltMov(String codUteUltMov) {
this.codUteUltMov = codUteUltMov;
}
public Date getDatOraUltMov() {
return this.datOraUltMov;
}
public void setDatOraUltMov(Date datOraUltMov) {
this.datOraUltMov = datOraUltMov;
}
public String getDesReg() {
return this.desReg;
}
public void setDesReg(String desReg) {
this.desReg = desReg;
}
public List<Tpg1029Provnuoist> getTpg1029Provnuoists() {
return this.tpg1029Provnuoists;
}
public void setTpg1029Provnuoists(List<Tpg1029Provnuoist> tpg1029Provnuoists) {
this.tpg1029Provnuoists = tpg1029Provnuoists;
}
public Tpg1029Provnuoist addTpg1029Provnuoist(Tpg1029Provnuoist tpg1029Provnuoist) {
getTpg1029Provnuoists().add(tpg1029Provnuoist);
tpg1029Provnuoist.setTwb1012Regione(this);
return tpg1029Provnuoist;
}
public Tpg1029Provnuoist removeTpg1029Provnuoist(Tpg1029Provnuoist tpg1029Provnuoist) {
getTpg1029Provnuoists().remove(tpg1029Provnuoist);
tpg1029Provnuoist.setTwb1012Regione(null);
return tpg1029Provnuoist;
}
public List<Twb1013Provincia> getTwb1013Provincias() {
return this.twb1013Provincias;
}
public void setTwb1013Provincias(List<Twb1013Provincia> twb1013Provincias) {
this.twb1013Provincias = twb1013Provincias;
}
public Twb1013Provincia addTwb1013Provincia(Twb1013Provincia twb1013Provincia) {
getTwb1013Provincias().add(twb1013Provincia);
twb1013Provincia.setTwb1012Regione(this);
return twb1013Provincia;
}
public Twb1013Provincia removeTwb1013Provincia(Twb1013Provincia twb1013Provincia) {
getTwb1013Provincias().remove(twb1013Provincia);
twb1013Provincia.setTwb1012Regione(null);
return twb1013Provincia;
}
}
So, into my project I have defined a Twb1012RegioneRepository interface that is my repository class defined on the previous Twb1012Regione entity class:
#RepositoryDefinition(domainClass=Twb1012Regione.class, idClass=String.class)
public interface Twb1012RegioneRepository extends JpaRepository<Twb1012Regione, String> {
// I have to implement it
}
Now my problem is that I want to create 2 methods (that implement 2 queries by method name as described by the previous tutorial) that perform the following tasks:
1) Return the list of all the Twb1012Regione representing all the record of the TWB1012_REGIONE table on the DB.
2) Given a specific id (the value of the String codReg field, PK of the Twb1012Regione class) I want to obtain the Twb1012Regione object associated to this record.
How can I implement these queries? I have some difficulties to do it
Tnx
You don't need to implement the methods. The Spring Data Repository API will construct query for you as the JpaRepository already has following methods:
List findAll(Iterable ids)
T getOne(ID id)
That's the whole point with the Spring Data Repository - To reduce the boiler plate code that you write.
I would like to put into db a class that have java.awt.geom.Point2D field. Is it possible?
Here is my code.
#Entity
#Table(name = "my_class_table")
public class MyClass {
private String aliasId;
private Point2D field;
public Point2D getField() {
return field;
}
public void setFieldPoint2D field) {
this.field = field;
}
public String getAliasId() {
return aliasId;
}
public void setAliasId(String aliasId) {
this.aliasId = aliasId;
}
}
And the reason of the exception which is thrown:
Could not determine type for: java.awt.geom.Point2D, at table: my_class_table, for columns: [org.hibernate.mapping.Column(field)]
Of course, the reason is quite obvious. My question is: how should I annotate the class to be able to use a field of Point2D class? Is it possible at all?
The simplest way is to use a java.awt.Point that extends Point2D and is a Serializable class. This way hibernate will automatically map it with SerializableType and you don't need to do anything more. The point object will be saved in its serialized form in a blob database table column.
You have also the option to define a custom hibernate type for the Point2D class. Here is a link of how to define a custom hibernate type.
You can't add annotations to existing classes.
But you can define a CompositeUserType to tell Hibernate how to map a Point2D.
Thanks guys for response. Unfortunatelly java.awt.Point class uses Integer, so it is useless in my case. The easiest way to solve it would be to use Point2D.Double which implements Serializable (but definition of UserType or CompositeUserType is more convenient if you don't want to change class definition). So, the simple solution:
#Entity
#Table(name = "my_class_table")
public class MyClass {
private String aliasId;
private Point2D.Double field;
public Point2D.Double getField() {
return field;
}
public void setField(Point2D.Double field) {
this.field = field;
}
public String getAliasId() {
return aliasId;
}
public void setAliasId(String aliasId) {
this.aliasId = aliasId;
}
}
But my final goal was to create a class with ordered list of points. If anybody is interested here is an example of the class representing line:
#Entity
public class Line {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "idDb", unique = true, nullable = false)
private int id;
#ElementCollection
#CollectionTable(name="points_table", joinColumns = #JoinColumn(name="idDb"))
#IndexColumn(name = "idx")
#Column(name="point_val")
private List<Point2D.Double> points = new ArrayList<Point2D.Double>();
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public List<Point2D.Double> getPoints() {
return points;
}
public void setPoints(List<Point2D.Double> points) {
this.points = points;
}
}
I am writing a webservice to maintain a database. I am trying to use JPA (EclipseLink) for the entity classes. However, the database uses natural primary keys and therefore there's potential that an update on the ID fields will fail due to foreign key constraints. Our DBA has provided a function to update the ID fields which will create a new parent record with the updated ID, update the child records to point to the new parent and delete the old parent.
If the ID fields could be updated "normally", I would have a situation like this:
#Entity
#Table(name = "PARENT")
public class Parent implements Serializable
{
private static final long serialVersionUID = 1L;
private String parent;
private String attribute;
private Set<Child> childs;
public Parent()
{
}
#Id
#Column(name = "PARENT")
public String getParent()
{
return this.parent;
}
public void setParent(String parent)
{
this.parent = parent;
}
#Column(name = "ATTRIBUTE")
public String getAttribute()
{
return this.attribute;
}
public void setAttribute(String attribute)
{
this.attribute = attribute;
}
#OneToMany(mappedBy = "parentBean")
public Set<Child> getChilds()
{
return this.childs;
}
public void setChilds(Set<Child> childs)
{
this.childs = childs;
}
}
#Entity
#Table(name = "CHILD")
public class Child implements Serializable
{
private static final long serialVersionUID = 1L;
private String child;
private String attribute;
private Parent parentBean;
public Child()
{
}
#Id
#Column(name = "CHILD")
public String getChild()
{
return this.child;
}
public void setChild(String child)
{
this.child = child;
}
#Column(name = "ATTRIBUTE")
public String getAttribute()
{
return this.attribute;
}
public void setAttribute(String attribute)
{
this.attribute = attribute;
}
#ManyToOne
#JoinColumn(name = "PARENT")
public Parent getParent()
{
return this.parent;
}
public void setParent(Parent parent)
{
this.parent = parent;
}
}
I also have a GenericServiceBean class with a method to call functions:
#Stateless
public class GenericServiceBean implements GenericService
{
#PersistenceContext(unitName = "PersistenceUnit")
EntityManager em;
public GenericServiceBean()
{
// empty
}
#Override
public <T> T create(T t)
{
em.persist(t);
return t;
}
#Override
public <T> void delete(T t)
{
t = em.merge(t);
em.remove(t);
}
#Override
public <T> T update(T t)
{
return em.merge(t);
}
#Override
public <T> T find(Class<T> type, Object id)
{
return em.find(type, id);
}
. . .
#Override
public String executeStoredFunctionWithNamedArguments(String functionName,
LinkedHashMap<String, String> namedArguments)
{
Session session = JpaHelper.getEntityManager(em).getServerSession();
StoredFunctionCall functionCall = new StoredFunctionCall();
functionCall.setProcedureName(functionName);
functionCall.setResult("RESULT", String.class);
for (String key : namedArguments.keySet())
{
functionCall.addNamedArgumentValue(key, namedArguments.get(key));
}
ValueReadQuery query = new ValueReadQuery();
query.setCall(functionCall);
String status = (String)session.executeQuery(query);
return status;
}
}
If I set the ID fields to be not editable:
#Id
#Column(name = "PARENT", udpatable=false)
public String getParent()
{
return this.parent;
}
and call parent.setParent(newParent) will this still update the ID in the entity object? How does this affect any child entities? Will they also be updated (or not)?
Another scenario I don't know how to deal with is where I need to update both the ID and another attribute. Should I call the function which updates (and commits) the ID in the database then make calls to set both the ID and attribute via the normal set* methods and then the persistence context will only commit the attribute change?
Perhaps this is a situation where JPA is not appropriate?
Any advice on this is greatly appreciated.
If I set the ID fields to be not editable (...) and call parent.setParent(newParent) will this still update the ID in the entity object? How does this affect any child entities? Will they also be updated (or not)?
updatable=false means that the column won't be part of the SQL UPDATE statement regardless of what you do at the object level so the Id shouldn't be updated. And I'm also tempted to say that child entities shouldn't be affected, especially since you're not cascading anything.
Another scenario I don't know how to deal with is where I need to update both the ID and another attribute (...)
Well, my understanding is that you'd have to call the function anyway so I would call it first.
Perhaps this is a situation where JPA is not appropriate?
I'm not sure raw SQL would deal better with your situation. Actually, the whole idea of changing primary keys sounds strange if I may.