Am trying to create a model class to store an Entity in Google App Engine using Eclipse.But when i save my work i get the error message:
org.datanucleus.metadata.MetaDataManager initialiseFileMetaDataForUse.
SEVERE: Class "com.packagename.classname" has been specified with an object-id class javax.jdo.identity.StringIdentity yet no fields have been identified as primary key fields. Please notate using the "primary-key" tag against the fields that should be considered part of the primary key.
If my understanding of JPA is correct, i do not need a primary-key for an entity since i already have a #Id tag.Here is my class.
#Entity
public class MyCLassName {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private static String userName;
private static String location;
private static Date dateOfBirth;
private static int age;
private static String gender;
private static String teamName;
private static int weight;
//Constructor with arguments
public MyClassName(String userName, String location, String gender, int age, Date DOB, int weight) {
MyClassName.userName = userName;
MyClassName.location = location;
MyClassName.gender = gender;
MyClassName.age=age;
MyClassName = DOB;
MyClassName.weight = weight;
}
//setter methods
public static void setUserName(String userName) {
MyClassName.userName = userName;
}
public static void setLocation(String location) {
MyClassName.location = location;
}
public static void setGender(String gender) {
MyClassName.gender = gender;
}
public static void setAge(int age) {
MyClassName.age = age;
}
public static void setDateOfBirth(Date dateOfBirth) {
MyClassName.dateOfBirth = dateOfBirth;
}
public static void setWeight(int weight) {
MyClassName.weight = weight;
}
//getter methods
public static String getUserName() {
return userName;
}
public static int getWeight() {
return weight;
}
public static String getLocation() {
return location;
}
public static String getGender() {
return gender;
}
public static String getTeamName() {
return teamName;
}
public static Date getDateOfBirth() {
return dateOfBirth;
}
public static int getAge() {
return age;
}
}
What exactly am i doing wrong here?
Your understanding of JPA is partially correct. You do not need to assign the primary key because you have used the #Id and #GeneratedValue annotation. The JPA implementation will automatically generate the primary key value as a long integer. However it still needs a field in which to store this ID value. It is trying to do that in userName. See Java Tutorial ID Generation Type: IDENTITY for example.
Related
i'm new to Springboot. I'm trying to implement a simple REST api using :
-Springboot, JPA & rest along with hibernate
I have a 2 tables database, Notebook that contains 1 to many notes
I already setup the 2 tables and relationships. I also created a NotebookRepository and NoteRepository to get basic CRUD operations via the springboot rest. The Database connection and relationships are functionning
but i don't know how to add a new note (it has a notebook_id foreign key which msut NOT be NULL) and everytime i tryto post something along these lines
{
"title:"abc",
"text":"whatever",
"notebook":{
"id":2
}
}
i get this error :
Caused by: java.sql.SQLIntegrityConstraintViolationException: Column 'notebook_id' cannot be null
#Entity
#Table(name="notebook")
public class NoteBook {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="id")
private int id;
#Column(name="name")
private String name;
#OneToMany(mappedBy="notebook", cascade=CascadeType.ALL)
List<Note> notes;
public NoteBook() {
}
public NoteBook(String name) {
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Note> getNotes() {
return notes;
}
public void setNotes(List<Note> notes) {
this.notes = notes;
}
public void addNote(Note note) {
if(notes == null) {
notes = new ArrayList<>();
}
note.setNotebook(this);
notes.add(note);
}
#Entity
#Table(name="note")
public class Note {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="id")
private int id;
#Column(name="title")
private String title;
#Column(name="text")
private String text;
#ManyToOne(cascade={CascadeType.MERGE, CascadeType.DETACH, CascadeType.PERSIST, CascadeType.REFRESH})
#JoinColumn(name="notebook_id")
private NoteBook notebook;
public Note() {
}
public Note(String title, String text) {
this.title = title;
this.text = text;
}
#RepositoryRestResource(collectionResourceRel = "note", path = "notes")
public interface NoteRepository extends JpaRepository<Note, Integer>{
//No code...
}
#RepositoryRestResource(collectionResourceRel = "notebook", path = "notebooks")
public interface NotebookRepository extends JpaRepository<NoteBook, Integer>{
}
The problem is that the class Note doesn't have a constructor with NoteBook parameter to pass the created NoteBook object to, so the solution is to add this constructor:
public Note(String title, String text, NoteBook noteBook) {
this.title = title;
this.text = text;
this.noteBook = noteBook;
}
and it's enough to send the JSON object as you do, but just be aware of case-sensitivity:
{ "title:"abc", "text":"whatever", "noteBook":{ "id":2 } }
I think you need to add referencedColumnName = "id" for JoinColumn annotation for notebook field in Note class.
Maybe you have problem with IDENTITY generation type. See this problem with null pointer
Not sure why I have an issue here, but when I save with a CrudRepository with these objects, I get the SerializationException (with no further information). Can someone take a look at my objects and offer me some insight into why they can't serialize? My pom.xml is attached last as well in case that helps somehow. I'm using a Postgres database.
EDIT: The database and now - tables are created, but objects are not creating rows.
The actual CrudRepository interface:
public interface AccountRepository extends CrudRepository<ZanyDishAccount, String> {}
ZanyDishAccount entity:
#Entity
public class ZanyDishAccount {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id; // internal id of the customer account for a Zany Dish subscription
private String status;
#OneToOne(cascade=CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "company_id")
private Company company;
#OneToOne(cascade=CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "order_id")
private Order order;
public ZanyDishAccount() {}
public ZanyDishAccount(Company company, Order order) {
this.company = company;
this.order = order;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Company getCompany() {
return company;
}
public void setCompany(Company company) {
this.company = company;
}
public Order getOrder() {
return order;
}
public void setOrder(Order order) {
this.order = order;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
#Override
public String toString()
{
return "ClassPojo [id = "+id+ ", company = " + company + ", status = " + status + "]";
}
}
Company entity:
#Entity
public class Company {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
Long id;
private String phoneNumber;
private String website;
private String name;
private String uuid;
private String country;
public Company() {}
public Company(String phoneNumber, String website, String name, String uuid, String country) {
this.phoneNumber = phoneNumber;
this.website = website;
this.uuid = uuid;
this.country = country;
}
public String getPhoneNumber ()
{
return phoneNumber;
}
public void setPhoneNumber (String phoneNumber)
{
this.phoneNumber = phoneNumber;
}
public String getWebsite ()
{
return website;
}
public void setWebsite (String website)
{
this.website = website;
}
public String getName ()
{
return name;
}
public void setName (String name)
{
this.name = name;
}
public String getUuid ()
{
return uuid;
}
public void setUuid (String uuid)
{
this.uuid = uuid;
}
public String getCountry ()
{
return country;
}
public void setCountry (String country)
{
this.country = country;
}
#Override
public String toString()
{
return "ClassPojo [phoneNumber = "+phoneNumber+", website = "+website+", name = "+name+", uuid = "+uuid+", country = "+country+"]";
}
}
Order entity:
#Entity
#Table(name = "_order")
public class Order {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
Long id;
private String pricingDuration;
private Items[] items;
private String editionCode;
public Order() {}
public Order(String pricingDuration, Items[] items, String editionCode) {
this.pricingDuration = pricingDuration;
this.items = items;
this.editionCode = editionCode;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getPricingDuration ()
{
return pricingDuration;
}
public void setPricingDuration (String pricingDuration)
{
this.pricingDuration = pricingDuration;
}
public Items[] getItems ()
{
return items;
}
public void setItems (Items[] items)
{
this.items = items;
}
public String getEditionCode ()
{
return editionCode;
}
public void setEditionCode (String editionCode)
{
this.editionCode = editionCode;
}
#Override
public String toString()
{
return "ClassPojo [pricingDuration = "+pricingDuration+", items = "+items+", editionCode = "+editionCode+"]";
}
}
Thanks for your help!
Mike
Hm, this seems multi-faceted. Let's see if I can help at all. Last thing first...
No tables being created automatically.
I would take a look at this section in Spring's docs for the most basic approach: Initialize a database using Hibernate. For example, spring.jpa.hibernate.ddl-auto: create-drop will drop and re-create tables each time the application runs. Simple and easy for initial dev work. More robust would be leveraging something like Flyway or Liquibase.
Serialization issue
So without logs, and the fact that you have no tables created, the lack of a persistence layer would be the assumed culprit. That said, when you have tables and data, if you do not have a repository for all of the related tables, you'll end up with a StackOverflow error (the serialization becomes circular). For that, you can use #JsonBackReference (child) and #JsonManagedReference (parent). I have been successful using only #JsonBackReference for the child.
Items[]
I'm not sure what Item.class looks like, but that looks like an offensive configuration that I missed the first round.
Change private Items[] items; to private List<Item> items = new ArrayList<Item>();. Annotate with #ElementCollection.
Annotate Item.class with #Embeddable.
I want to convert one immutable object to another immutable objects. I googled and found that Dozzer and Orika are mostly used for object mappings.
I tried using Dozzer but seems that it doesn't work well with objects created using builder pattern.
Example:
//Source Object
public class EmployeeDTO{
private String id;
private String name;
private void setName(String name){this.name=name;}
private void setId(String id){this.id=id;}
public static class Builder{
public String id;
public String name;
public Builder setName(String name){this.name=name;}
public Builder setId(String id){this.id=id;}
public EmployeeDTO build(){
EmployeeDTO employeeDTO = new EmployeeDTO();
employeeDTO.setName(this.name);
employeeDTO.setId(this.id);
return employeeDTO;
}
}
}
//Target Object
public class Employee{
private String id;
private String name;
private void setName(String name){this.name=name;}
private void setId(String id){this.id=id;}
public static class Builder{
public String id;
public String name;
public Builder setName(String name){this.name=name;}
public Builder setId(String id){this.id=id;}
public Employee build(){
Employee employee = new Employee();
employee.setName(this.name);
employee.setId(this.id);
return employee;
}
}
}
I want to convert these two structures interchangeably. I have little idea that I can create custommapper to perform this task. Please help me if it is possible with Dozzer/Orika in easy way.
public class SourceObjectClass implements T{
private final String name;
private final int id;
public sourceObjectClass(final String name, final int id){
this.name = name;
this.id = id;
}
public String getName(){
return name;
}
public String getId(){
return id;
}
}
//Destination Object
public class DestinationObjectClass implements T{
private final String name;
private final int id;
public sourceObjectClass(final String name, final int id){
this.name = name;
this.id = id;
}
public String getName(){
return name;
}
public String getId(){
return id;
}
}
//Converter
//Converter
public class MyConverter{
public static T convert(SourceObjectClass sourceObject, Class<T> destinationClass){
Class definition = Class.forName(destinationClass);
return definition.newInstance(sourceObject.getName(),sourceObject.getId());
}
}
public class MyTestClass{
public static void main(String args[]){
//Create an immutable object
SourceClasssObject sourceObject = new SourceClassObject("Guest",100);
//convert the above object into another immutable Object
final DestinationObjectClass destination = MyConverter.convert(sourceObject,DestinationObjectClass.class);
}
}
I have a class like this...
#Entity
public class User{
private String userId;
#Id
public String getUserId(){
return userId;
}
public void setUserId(String userId){
this.userId = userId;
}
}
#Embeddible
public class RegPk{
private String serial;
private String userId;
....
}
#Entity
#IdClass(RegPk.class)
public class Registration {
private String userId, serial;
private User user
#Id
#Column(name="SRL_C")
public String getSerial() {return serial;}
public void setSerial(String serial) {this.serial = serial;}
#ManyToOne(cascade={CascadeType.REFRESH})
#JoinColumn(name="USERID", referencedColumnName="USERID", nullable = false)
public User getUser() {return user;}
public void setUser(User user) {this.user = user;}
#Id
#Column(name="USERID", nullable = false)
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
}
RegPk pk = new RegPk();
pk.setSerial(dr.getSerial());
pk.setUserId(dr.getUserId());
Registration userOld = em.find(Registration.class, pk);
But when I try to run it I get null back. I swear I thought I had it working so...
1.) is this kind of thing even possible?
2.) what am I doing wrong?
Yes, it's possible, provided you use the MapsId annotation. Otherwise, you have two different fields mapped to the same column, which is invalid.
The javadoc provides an example which almost matches exactly with your situation.
I want to copy the entity's UUID, generated at run time to another field.
The entity id is generated via the code described bellow:
package eclipselink.example;
public class UUIDSequence extends Sequence implements SessionCustomizer {
public UUIDSequence() {
super();
}
public UUIDSequence(String name) {
super(name);
}
#Override
public Object getGeneratedValue(Accessor accessor,
AbstractSession writeSession, String seqName) {
return UUID.randomUUID().toString().toUpperCase();
}
...
public void customize(Session session) throws Exception {
UUIDSequence sequence = new UUIDSequence("system-uuid");
session.getLogin().addSequence(sequence);
}
}
Persitence.xml:
property name="eclipselink.session.customizer" value="eclipselink.example.UUIDSequence"
The entity:
public abstract class MyEntity{
private String id;
private String idCopy;
#Id
#Basic(optional = false)
#GeneratedValue(generator="system-uuid")
#XmlElement(name = "ID")
public String getId() {
return id;
}
}
How can I instruct JPA (Eclipse-link) to copy the UUID generated at runtime to idCopy field as well?
I'm not 100% sure this will work (I don't know if EclipseLink calls the setter or assigns the field directly), but give this a try:
public abstract class MyEntity{
private String id;
private String idCopy;
#Id
#Basic(optional = false)
#GeneratedValue(generator="system-uuid")
#XmlElement(name = "ID")
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
this.idCopy = id;
// or
// this.setIdCopy(id);
}
}