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Am I using OneToOne relationship right?

Hello I am actually working on a REST server using Spring-boot, hibernate, psql and I am experiencing some difficulties after adding an OneToOne relationship between entities.
Here are the 2 entities:
Pays:
#Entity
#Table(name = "pays")
public class Pays implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#JsonProperty("codePays")
private String codePays;
#Column(name = "libelle_pays")
#JsonProperty("libellePays")
private String libellePays;
#OneToOne(mappedBy = "pays",cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional=false)
private Traduction traduction;
protected Pays() {
}
public Pays(String codePays,String libellePays) {
this.codePays = codePays;
this.libellePays = libellePays;
}
and Traduction:
#Entity
#Table(name = "traduction")
public class Traduction implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#JsonProperty("codeTrad")
private long codeTrad;
#Column(name = "defaultLanguage")
#JsonProperty("defaultLanguage")
private boolean defaultLanguage;
#OneToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
#JoinColumn(name="fk_code_pays")
#JsonProperty("codePays")
private Pays pays;
public Traduction(){
}
public Traduction(String codePays,boolean defaultLanguage) {
this.defaultLanguage = defaultLanguage;
pays.setCodePays(codePays);
}
My problem happen when I try to populate my table traduction using a Post method:
#PostMapping("/traduction")
public Traduction createTraduction(#RequestBody Traduction trad) {
System.err.println(trad);
return repository.save(trad);
}
when I send JSON data to my server via PostMan like this:
{
"codeTrad":0,
"defaultLanguage":true,
"fk_code_pays":"FR"
}
or this way:
{
"codeTrad":0,
"defaultLanguage":true,
"pays":
{
"codePays":"FR",
"libellePays":"France"
}
}
My server doesn't seem to understand the mapping with the object Pays.
Here what the object Traduction look like after my request:
[codeTrad=0, null, defaultLanguage=true]
and the pretty error:
Resolved [org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: (was java.lang.NullPointerException); nested exception is com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: com.auchan.corp.ipon.iponportail.model.Traduction["codePays"])]
So I am wondering if the problem comes from my server conception or just my JSON. Do you have an idea?

Your issue comes from :
public Traduction(String codePays, boolean defaultLanguage) {
this.defaultLanguage = defaultLanguage;
pays.setCodePays(codePays)
The pays is null and that's why you get an exception : java.lang.NullPointerException, well try to add Pays pays to that constructor.

This json won't work:
{ "codeTrad":0, "defaultLanguage":true, "fk_code_pays":"FR" }
as there is no field name fk_code_pays in your Traduction class.
Below won't work either:
{ "codeTrad":0, "defaultLanguage":true, "pays": { "codePays":"FR", "libellePays":"France" } }
Because pays is annotated with #JsonProperty("codePays")
As per your DTO classes, your json should be:
{ "codeTrad":0, "defaultLanguage":true, "codePays": { "codePays":"FR", "libellePays":"France" } }
Also I would recommend you to use wrapper classes in place of primitives. Boolean in place of boolean and Long in place of long.

Why user defined #javax.persistence.Converter isn't recognized by hibernate when mapping the entity field to database column

I have the following Entity containing a field of Enum type:
#Entity
#Table(name = "INPUT_DATA")
public class InputDataEntity implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#SequenceGenerator(name = "INPUT_DATA_SEQ", allocationSize = 1, sequenceName = "INPUT_DATA_SEQ")
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "INPUT_DATA_SEQ")
private Long id;
#Column(name = "FIELD1", nullable = false)
private String field1;
#Column(name = "FIELD2", nullable = false)
#Convert(converter = Type.Converter.class)
private Type field2;
// getters and setters
}
The Enum type looks like:
public enum Type {
ENUM_ITEM_1("item1"),
// more items
ENUM_ITEM_N("itemN");
private String code;
private Type(String code) {
this.code = code;
}
public static Type fromString(String name) {
switch (name) {
case "item1":
return ENUM_ITEM_1;
// more cases
case "itemN":
return ENUM_ITEM_N;
default:
throw new IllegalArgumentException("Wrong value for Type");
}
}
#Override
public String toString() {
return code;
}
#javax.persistence.Converter
public static class Converter implements AttributeConverter<Type, String> {
#Override
public String convertToDatabaseColumn(Type attribute) {
return attribute.toString();
}
#Override
public Type convertToEntityAttribute(String s) {
return Type.fromString(s);
}
}
}
The problem is that hibernate doesn't recognize my Converter when I want to fetch data from the database.
I've also tried:
#Embedded and #Embeddable but with no luck.
#Enumerated(EnumType.STRING) but again with no luck.
My question is:
how to make hibernate to recognize my converter when converting the appropriate field?
Many thanks in advance.

I eventually ended up by implementing a StringValuedEnum interface and its relevant reflector and type class by implementing EnhancedUserType, ParameterizedType as it was described here.
This helped me to properly store into and retrieve from DB data corresponding to user defined enum types, although the questions with converters remains still open. If someday a proper answer will be given, that will be very appreciated.

JpaRepository findOne(id) returns null

This is my first post here, I've been searching for a long time here but I didn't found a problem that seemed similar.
When I use JpaRepository function findOne(id) for one of my classes, it returns null. As if no row had been found for this id.
Of course the database row with this id exists.
Also my class mapping seems right.
I don't understand because I already used findOne() for other classes and I never had any problem.
Anyone can tell me what can be the source of this problem, please ? That would be nice !
This is my DAO :
#Transactional
public interface OrderDetailDAO extends JpaRepository<OrderDetail, Integer>
{
}
This is my Model :
#Entity
#Table(name = "order_detail", schema = "", catalog = AppConfig.databaseSchema)
public class OrderDetail implements Serializable {
private int idOrderDetail;
private Order order;
private Preorder preorder;
private UnitType unitType;
private Sale sale;
private DeliveryStatusType deliveryStatusType;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_Order_Detail")
public int getIdOrderDetail() {
return idOrderDetail;
}
public void setIdOrderDetail(int idOrderDetail) {
this.idOrderDetail = idOrderDetail;
}
#ManyToOne
#JoinColumn(name = "id_Order", referencedColumnName = "id_Order", nullable = false)
public Order getOrder() {
return order;
}
public void setOrder(Order order) {
this.order = order;
}
#ManyToOne
#JoinColumn(name = "id_Preorder", referencedColumnName = "id_Preorder", nullable = false)
public Preorder getPreorder() {
return preorder;
}
public void setPreorder(Preorder preorder) {
this.preorder = preorder;
}
#ManyToOne
#JoinColumn(name = "id_Unit_Type", referencedColumnName = "id_Unit_Type")
public UnitType getUnitType() {
return unitType;
}
public void setUnitType(UnitType unitType) {
this.unitType = unitType;
}
#ManyToOne
#JoinColumn(name = "id_Sale", referencedColumnName = "id_Sale")
public Sale getSale() {
return sale;
}
public void setSale(Sale sale) {
this.sale = sale;
}
#ManyToOne
#JoinColumn(name = "id_Delivery_Status_Type", referencedColumnName = "id_Delivery_Status_Type")
public DeliveryStatusType getDeliveryStatusType() {
return deliveryStatusType;
}
public void setDeliveryStatusType(DeliveryStatusType deliveryStatusType) {
this.deliveryStatusType = deliveryStatusType;
}
}
When I write a request manually, like this :
#Query("SELECT o FROM OrderDetail o WHERE o.idOrderDetail = :idOrderDetail")
public OrderDetail findOneCustom(#Param("idOrderDetail") Integer idOrderDetail);
That works, but that's ugly so I would prefer to use JpaRepository native function findOne()

After all investigation, I have found an interesting answer that is worked for me. I think it is all about defining column type on Db. For my case, I have defined the variable (rid as column) as varchar2(18) that was RID CHAR(18 BYTE).
Java part:
if (dhFlightRepo.findOneFlight(dhFlight.getRid())== null) {
dhFlightRepo.save(dhFlight);
}
If your value that you used as a parameter for findOne() is smallest than set value on column (18 for my case),the jpa doesn't accept value and returns null.You have to change column type as varchar2(18) it can be changeable according to given value on findOne() and work perfect.
I hope that works for all of you.I kindly request to give more detail If someone knows the reason with more detail.

JPA persist entities with one to many relation

Config
EcliplseLink 2.3.2
JPA 2.0
The entities are auto created from the db schema from netbeans with Entity Classes from Database... wizard.
The controller classes are auto created from netbeans with JPA Controller Classes from Entity Classes... wizard
Short version of question
In a classic scenario, two tables with one to many relation. I create the parent entity, then the child entity and I attach the child to the parent's collection. When I create (controller method) the parent entity, I expect the child entity to be created to and associated with parent. Why doesn't it happen?
Long version
Parent class
#Entity
#XmlRootElement
public class Device implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
private Integer id;
#Column(unique=true)
private String name;
#Temporal(TemporalType.TIMESTAMP)
private Date updated;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "deviceId")
private Collection<NetworkInterface> networkInterfaceCollection;
public Device() {
}
public Device(String name) {
this.name = name;
updated = new Date();
}
// setters and getters...
#XmlTransient
public Collection<NetworkInterface> getNetworkInterfaceCollection() {
return networkInterfaceCollection;
}
public void setNetworkInterfaceCollection(Collection<NetworkInterface> networkInterfaceCollection) {
this.networkInterfaceCollection = networkInterfaceCollection;
}
public void addNetworkInterface(NetworkInterface net) {
this.networkInterfaceCollection.add(net);
}
public void removeNetworkInterface(NetworkInterface net) {
this.networkInterfaceCollection.remove(net);
}
// other methods
}
Child class
#Entity
#Table(name = "NETWORK_INTERFACE")
#XmlRootElement
public class NetworkInterface implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
private Integer id;
private String name;
#Temporal(TemporalType.TIMESTAMP)
private Date updated;
#JoinColumn(name = "DEVICE_ID", referencedColumnName = "ID")
#ManyToOne(optional = false)
private Device deviceId;
public NetworkInterface() {
}
public NetworkInterface(String name) {
this.name = name;
this.updated = new Date();
}
// setter and getter methods...
public Device getDeviceId() {
return deviceId;
}
public void setDeviceId(Device deviceId) {
this.deviceId = deviceId;
}
}
Main class
public class Main {
public static void main(String[] args) {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("wifi-dbPU");
DeviceJpaController deviceController = new DeviceJpaController(emf);
NetworkInterfaceJpaController netController = new NetworkInterfaceJpaController(emf);
Device device = new Device("laptop");
NetworkInterface net = new NetworkInterface("eth0");
device.getNetworkInterfaceCollection().add(net);
deviceController.create(device);
}
}
This class throws a NullPointerException in line: device.getNetworkInterfaceCollection().add(net);
The system knows that there is a new entity device and it has an element net in it's collection. I expected it to write device in db, get device's id, attach it to net and write it in db.
Instead of this, I found that these are the steps I have to do:
deviceController.create(device);
net.setDeviceId(device);
device.getNetworkInterfaceCollection().add(net);
netController.create(net);
Why do I have to create the child when the parent class knows it's child and it should create it for me?
The create method from DeviceJpaController (sorry for the long names in fields, they are auto generated).
public EntityManager getEntityManager() {
return emf.createEntityManager();
}
public void create(Device device) {
if (device.getNetworkInterfaceCollection() == null) {
device.setNetworkInterfaceCollection(new ArrayList<NetworkInterface>());
}
EntityManager em = null;
try {
em = getEntityManager();
em.getTransaction().begin();
Collection<NetworkInterface> attachedNetworkInterfaceCollection = new ArrayList<NetworkInterface>();
for (NetworkInterface networkInterfaceCollectionNetworkInterfaceToAttach : device.getNetworkInterfaceCollection()) {
networkInterfaceCollectionNetworkInterfaceToAttach = em.getReference(networkInterfaceCollectionNetworkInterfaceToAttach.getClass(), networkInterfaceCollectionNetworkInterfaceToAttach.getId());
attachedNetworkInterfaceCollection.add(networkInterfaceCollectionNetworkInterfaceToAttach);
}
device.setNetworkInterfaceCollection(attachedNetworkInterfaceCollection);
em.persist(device);
for (NetworkInterface networkInterfaceCollectionNetworkInterface : device.getNetworkInterfaceCollection()) {
Device oldDeviceIdOfNetworkInterfaceCollectionNetworkInterface = networkInterfaceCollectionNetworkInterface.getDeviceId();
networkInterfaceCollectionNetworkInterface.setDeviceId(device);
networkInterfaceCollectionNetworkInterface = em.merge(networkInterfaceCollectionNetworkInterface);
if (oldDeviceIdOfNetworkInterfaceCollectionNetworkInterface != null) {
oldDeviceIdOfNetworkInterfaceCollectionNetworkInterface.getNetworkInterfaceCollection().remove(networkInterfaceCollectionNetworkInterface);
oldDeviceIdOfNetworkInterfaceCollectionNetworkInterface = em.merge(oldDeviceIdOfNetworkInterfaceCollectionNetworkInterface);
}
}
em.getTransaction().commit();
} finally {
if (em != null) {
em.close();
}
}
}

I finally understood the logic behind persisting one to many entities. The process is:
Create parent class
Persist it
Create child class
Associate child with parent
Persist child (the parent collection is updated)
With code:
public class Main {
public static void main(String[] args) {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("wifi-dbPU");
DeviceJpaController deviceController = new DeviceJpaController(emf);
NetworkInterfaceJpaController netController = new NetworkInterfaceJpaController(emf);
Device device = new Device("laptop"); // 1
deviceController.create(device); // 2
NetworkInterface net = new NetworkInterface("eth0"); // 3
net.setDeviceId(device.getId()); // 4
netController.create(net); // 5
// The parent collection is updated by the above create
}
}
Now, I can find a device (with id for example) and I can get all its children using
Collection<NetworkInterface> netCollection = device.getNetworkInterfaceCollection()
In the device entity class, which I posted in the question, there is no need for the methods addNetworkInterface and removeNetwokrInterface.

#Dima K is correct in what they say. When you do this:
Device device = new Device("laptop");
NetworkInterface net = new NetworkInterface("eth0");
device.getNetworkInterfaceCollection().add(net);
deviceController.create(device);
The collection in device hasn't been initialized and so you get a NPE when trying to add to it. In your Device class, when declaring your Collection, you can also initialize it:
private Collection<NetworkInterface> networkInterfaceCollection = new CollectionType<>();
As for persisting, your assumptions are correct but I think the execution is wrong. When you create your device, make it persistent with JPA right away (doing transaction management wherever needed).
Device device = new Device("laptop");
getEntityManager().persist(device);
Do the same for the NetworkInterface:
NetworkInterface net = new NetworkInterface("eth0");
getEntityManager().persist(net);
Now since both your entities are persisted, you can add one to the other.
device.getNetworkInterfaceCollection().add(net);
JPA should take care of the rest without you having to call any other persists.

This is a known behavior of collection data members.
The easiest solution is to modify your collection getter to lazily create the collection.
#XmlTransient
public Collection<NetworkInterface> getNetworkInterfaceCollection() {
if (networkInterfaceCollection == null) {
networkInterfaceCollection = new Some_Collection_Type<NetworkInterface>();
}
return networkInterfaceCollection;
}
Also, remember to refer to this data member only through the getter method.

This exception means you're trying to locate an entity (probably by em.getReference()) that hasn't been persisted yet.
You cannot you em.getReference() or em.find() on entities which still don't have a PK.

In order to enable save ability on a #OneToMany relation e.g.
#OneToMany(mappedBy="myTable", cascade=CascadeType.ALL)
private List<item> items;
Then you have to tell to your #ManyToOne relation that it is allowed to update myTable like this updatable = true
#ManyToOne #JoinColumn(name="fk_myTable", nullable = false, updatable = true, insertable = true)

error updating parent-child relationship using Hibernate-JPA

My Hibernate-JPA domain model has these entities:
AttributeType ------< AttributeValue
The relevant Java classes look like this (getters and setters omitted):
#Entity
public class AttributeType {
#Id #GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(unique = true, nullable = false)
private String name;
#OneToMany(mappedBy = "attributeType", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
private List<AttributeValue> values = new ArrayList<AttributeValue>();
}
#Entity #Table(uniqueConstraints = #UniqueConstraint(columnNames = {"value", "attribute_type_id"}))
public class AttributeValue {
#Id #GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#ManyToOne(optional = false)
private AttributeType attributeType;
#Column(nullable = false)
private String value;
}
Notice there's a unique constraint on AttributeValue.value and AttributeValue.attributeType, because for an attribute type (e.g. size) we don't want to allow an attribute value (e.g. small) to occur more than once.
If I update an AttributeType by performing the following operations within a single transaction:
delete "small" attribute value from "size" attribute type
add "small" attribute value to "size" attribute type
I get an exception that indicates the unique constraint was violated. This suggests that Hibernate-JPA is performing the insertion of the attribute value before the delete, which seems to invite this kind of problem for no obvious reason.
The class that performs the update of an AttributeType looks like this:
#Transactional(propagation = Propagation.SUPPORTS)
public class SomeService {
private EntityManager entityManager; // set by dependency injection
#Transactional(propagation = Propagation.REQUIRED)
public AttributeType updateAttributeType(AttributeType attributeType) throws Exception {
attributeType = entityManager.merge(attributeType);
entityManager.flush();
entityManager.refresh(attributeType);
return attributeType;
}
}
I could workaround this problem by iterating over the attribute values, figuring out which ones have been updated/deleted/inserted, and performing them in this order instead:
deletes
updates
inserts
But it seems like the ORM should be able to do this for me. I've read that Oracle provides a "deferConstraints" option that causes constraints to be checked only when a transaction has completed. However, I'm using SQL Server, so this won't help me.

You need to use a composite ID instead of a generated ID.
HHH-2801
The problem arises when a new association entity with a generated ID
is added to the collection. The first step, when merging an entity
containing this collection, is to cascade save the new association
entity. The cascade must occur before other changes to the collection.
Because the unique key for this new association entity is the same as
an entity that is already persisted, a ConstraintViolationException is
thrown. This is expected behavior.
Using a new collection (i.e., one-shot delete), as suggested in the
previous comment) also results in a constraint violation, since the
new association entity will be saved on the cascade of the new
collection.
An example of one of the approaches (using a composite ID instead of a generated ID) is illustrated >in manytomanywithassocclass.tar.gz and is checked into Svn.
#Entity
public class AttributeType {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Integer id;
#Column(unique = true, nullable = false)
private String name;
#OneToMany(mappedBy = "attributeType", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
private List<AttributeValue> values = new ArrayList<AttributeValue>();
//Getter, Setter...
}
#Entity
#Table (uniqueConstraints = #UniqueConstraint(columnNames = { "value", "attributeType_id" }))
public class AttributeValue{
#EmbeddedId AttributeValueId id;
#MapsId(value= "id")
#ManyToOne(optional = false)
private AttributeType attributeType;
private String value2;
public AttributeValue() {
this.id = new AttributeValueId();
}
public AttributeType getAttributeType() {
return attributeType;
}
public void setAttributeType(AttributeType pAttributeType) {
this.id.setAttributeTypeID(pAttributeType.getId());
this.attributeType = pAttributeType;
}
public String getValue() {
return id.getAttributeValue();
}
public void setValue(String value) {
this.id.setAttributeValue(value);
}
#Embeddable
public static class AttributeValueId implements Serializable {
private Integer id;
private String value;
public AttributeValueId() {
}
public AttributeValueId(Integer pAttributeTypeID, String pAttributeValue) {
this.id = pAttributeTypeID;
this.value = pAttributeValue;
}
public Integer getAttributeTypeID() {
return id;
}
public void setAttributeTypeID(Integer attributeTypeID) {
this.id = attributeTypeID;
}
public String getAttributeValue() {
return value;
}
public void setAttributeValue(String attributeValue) {
this.value = attributeValue;
}
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime
* result
+ ((id == null) ? 0 : id
.hashCode());
result = prime
* result
+ ((value == null) ? 0 : value.hashCode());
return result;
}
#Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
AttributeValueId other = (AttributeValueId) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
if (value == null) {
if (other.value != null)
return false;
} else if (!value.equals(other.value))
return false;
return true;
}
}
}
See 5.1.2.1. Composite identifier on how to do it with JPA annotation.
See Chapter 8. Component Mapping
See 8.4. Components as composite identifiers

I am not sure if I understand the question as it is getting late, but first thing I would try would be to override AttributeValue's equals method to contain those two unique fields.

In hibernate session there is one queue for the delete and one for the insert. Debug to see if deletes comes before insert.
Look at the merge. Try using update instead.