please excuse my bad English...
In my database there are stored article sets. In every article sets there are several different articles in it. Each article has a different demand with a date and a quantity.
In the project there is an enum which looks like this:
public enum PeriodDefinition {
Individual,
Day,
Week,
Month,
Quarter,
HalfYear,
Year
}
The entity of Article is like that:
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Entity;
import javax.persistence.ManyToMany;
#Entity
public class Article extends ArticleContainer {
private float price;
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
}
The entity of Article Container:
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.OneToOne;
#Entity
public class ArticleContainer extends BaseEntity {
#Column(nullable = false, unique = true)
private String number;
#Column(nullable = false)
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
}
The Entity of Article Set:
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Entity;
import javax.persistence.ManyToMany;
import javax.persistence.OneToMany;
#Entity
public class ArticleSet extends ArticleContainer {
private static final long serialVersionUID = 6236522228097421880L;
#ManyToMany
private List<Article> articles = new ArrayList<Article>();
#OneToMany
private List<ArticleSet> children = new ArrayList<ArticleSet>();
public List<Article> getArticles() {
return articles;
}
public void setArticles(List<Article> articles) {
this.articles = articles;
}
public List<ArticleSet> getChildren() {
return children;
}
public void setChildren(List<ArticleSet> children) {
this.children = children;
}
}
And finally the Demand entity
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.ManyToOne;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
#Entity
public class Demand extends BaseEntity {
#ManyToOne(optional = false)
private Article article;
#Temporal(TemporalType.TIMESTAMP)
#Column(nullable = false)
private Date demandTime;
private double quantity;
public Article getArticle() {
return article;
}
public void setArticle(Article article) {
this.article = article;
}
public Date getTimeStamp() {
return demandTime;
}
public void setTimeStamp(Date demandTime) {
this.demandTime = demandTime;
}
public double getQuantity() {
return quantity;
}
public void setQuantity(double quantity) {
this.quantity = quantity;
}
}
For example there exists an article set with the name "ArticleSetOfTwo" and the number 002 and contains the articles "Article 1" and "Article 2" with the numbers 1 and 2.
Article 1 has the following demand: (Left is date and right is quantity)
07-11-2011, 10
08-11-2011, 50
15-11-2011, 200
15-11-2011, 300
16-11-2011, 100
Article 2 has the following demand:
08-11-2011, 20
09-11-2011, 10
14-11-2011, 150
15-11-2011, 150
16-11-2011, 100
Now I want to sum all quantities in the article set divided by a period of our enum, e.g. week. Then this would be for the Articleset:
For the first week starting at 07-11-2011 until 13-11-2011 it would be: 90
For the second week starting at 14-11-2011 until 20-11-2011 it would be: 1000
These values I'd like to store in a ArrayList but I don't know how to do it. Maybe someone can solve it. Thank you very much in advance!
I'm not sure it's doable using a query.
I would just select all the date/quantity pairs for the article set, ordered by date, and then do a loop starting from the start date and ending with the end date, and add the quantities in Java.
The HQL would look like this:
select d.demandTime, d.quantity from Demand d, ArticleSet set
inner join set.articles article
where d.article = article
order by d.demandTime
Then, for each week, loop through the pairs and, if the demand time is between the start and the end of the week, add the quantity of the demand to the week sum.
Related
Today I did some experiments with hibernate. Unfortunately it seems if I’m misunderstanding something about the sessions.
I have three entities (book “buch”, user “benutzer” and rent “leihstellung”).
Each book knows about the rents, it’s concerned by. Each rent knows about the associated book. Furthermore each rent knows about the fitting user and of course each user knows the associated rents.
I explicitly want to have this two way mappings.
Now I wrote a small tester which inserts some data. The insert progress works as expected. After inserting some data I would like to delete a user.
If I do this before the commit, hibernate gives me an error, because the user will be reinserted be the rents it belongs to (that even happens, if I manually delete the user from this rents). Here I don’t really understand why that happens.
Everything works fine, if I do a session.close and open a new session for deleting the user.
I guess, that there is a smarter way to do this within one session. But unfortunately I don’t know how this can be done.
Any explanation is welcome.
public class Worker implements Iworker{
private Sessiongetter sg;
private MainMenu mm;
public void work(File datei)
{
sg = new Sessiongetter();
Session session = sg.getSesseion();
WlBuchart wlBuchart = new WlBuchart(1, "Sachbuch");
Buch buch = new Buch("test", "ich", 1);
buch.setWlBuchart(wlBuchart);
Buch buch2 = new Buch("versuch", "du",2);
buch2.setWlBuchart(wlBuchart);
session.beginTransaction();
session.save(wlBuchart);
session.save(buch);
session.save(buch2);
Benutzer benutzer = new Benutzer("hans", "dampf", "Lehrer", "versuch");
session.save(benutzer);
Leihstellung leihstellung = new Leihstellung(benutzer, buch);
Leihstellung leihstellung2 = new Leihstellung(benutzer, buch2);
session.save(leihstellung);
session.save(leihstellung2);
benutzer.addLeihstellung(leihstellung);
benutzer.addLeihstellung(leihstellung2);
session.update(benutzer);
buch.addLeihstellung(leihstellung);
buch2.addLeihstellung(leihstellung2);
session.update(buch);
session.update(buch2);
session.remove(benutzer);
session.flush();
session.getTransaction().commit();
session.close();
System.out.println("fertig");
}
package code.logik;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.Session;
#Entity
#Table(name="benutzer")
public class Benutzer {
#Column(nullable=false)
private String vorname, nachname, gruppe;
#Id
private String kennung;
private boolean admin;
#Column(nullable=true)
private String kennwort;
#OneToMany(cascade=CascadeType.ALL, mappedBy="benutzer")
private List<Leihstellung>leihstellungs;
public String getKennwort() {
return kennwort;
}
public void setKennwort(String kennwort) {
this.kennwort = kennwort;
}
public Benutzer(String vorname, String nachname, String gruppe, String kennung) {
this.vorname=vorname;
this.nachname=nachname;
this.gruppe=gruppe;
this.kennung=kennung;
this.leihstellungs= new ArrayList<>();
}
public Benutzer() {
// TODO Auto-generated constructor stub
}
public String getVorname() {
return vorname;
}
public String getNachname() {
return nachname;
}
public String getGruppe() {
return gruppe;
}
public String getKennung() {
return kennung;
}
public boolean isAdmin() {
return admin;
}
public void setAdmin(boolean admin) {
this.admin = admin;
}
public List<Leihstellung> getLeihstellungs() {
return leihstellungs;
}
public void addLeihstellung(Leihstellung leihstellung)
{
leihstellungs.add(leihstellung);
}
public int compare(Benutzer other)
{
if (this.getNachname().compareTo(other.getNachname())!=0)
{
return this.getNachname().compareTo(other.getNachname());
}
return this.getVorname().compareTo(other.getVorname());
}
}
package code.logik;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.annotations.ManyToAny;
#Entity
#Table(name="buch")
public class Buch {
#Column(nullable=false)
private String titel;
private String autor;
#ManyToOne
private WlBuchart wlBuchart;
#OneToMany(cascade=CascadeType.ALL, mappedBy="buch")
private List<Leihstellung>leihstellungs;
public WlBuchart getWlBuchart() {
return wlBuchart;
}
public void setWlBuchart(WlBuchart wlBuchart) {
this.wlBuchart = wlBuchart;
}
#Id
private int nummer;
public Buch(String titel, String autor,int nummer) {
this.titel=titel;
this.autor=autor;
this.nummer=nummer;
leihstellungs = new ArrayList<>();
}
public Buch() {
// TODO Auto-generated constructor stub
}
public String getTitel() {
return titel;
}
public String getAutor() {
return autor;
}
public int getNummer() {
return nummer;
}
public List<Leihstellung> getLeihstellungs() {
return leihstellungs;
}
public void addLeihstellung(Leihstellung leihstellung)
{
leihstellungs.add(leihstellung);
}
}
package code.logik;
import java.time.LocalDate;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
#Entity
#Table(name="leihstellung")
public class Leihstellung {
#ManyToOne
private Benutzer benutzer;
#Id #GeneratedValue
private int id;
#Column(nullable=false)
private LocalDate von;
private LocalDate bis;
#ManyToOne
private Buch buch;
public Leihstellung(Benutzer benutzer, Buch buch) {
this.benutzer=benutzer;
this.buch=buch;
this.von = LocalDate.now();
}
public Leihstellung() {
// TODO Auto-generated constructor stub
}
public void setAbgegeben()
{
bis = LocalDate.now();
}
public Benutzer getBenutzer() {
return benutzer;
}
public int getId() {
return id;
}
public LocalDate getVon() {
return von;
}
public LocalDate getBis() {
return bis;
}
public Buch getBuch() {
return buch;
}
}
Found the solution myself. I had to delete the references from the connected rents and books.
Now everything works find.
I want to establish one to many relation between table vendor detail and product detail. like one vendor can have multiple products. but when i am inserting data into table its inserting all the four fields but not mapping vendorid into ProductDetail Table
and query generated is this.
Hibernate: insert into ProductInfo (productCategory, productDetails, productPrice, VendorId) values (?, ?, ?, ?) It shuld map vendor ID also but in table its empty.
VendorDetail.java
package com.cts.entity;
import javax.persistence.*;
#Entity
#Table(name = "VendorInfo")
public class VendorDetails {
#Id
#Column
private Long VendorId;
#OneToMany
private ProductDetails productdetail;
#Column
private String VendorName;
#Column
private String Password;
public String getVendorName() {
return VendorName;
}
public void setVendorName(String vendorName) {
VendorName = vendorName;
}
public Long getVendorId() {
return VendorId;
}
public void setVendorId(Long vendorId) {
VendorId = vendorId;
}
public String getPassword() {
return Password;
}
public void setPassword(String password) {
Password = password;
}
}
ProductDetails.java
package com.cts.entity;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;
import javax.persistence.Table;
#Entity#Table(name = "ProductInfo")
public class ProductDetails {
#ManyToOne(cascade = CascadeType.ALL)#JoinColumn(name = "VendorId")
private VendorDetails vendordetails;
public ProductDetails() {
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private int productId;
#Column
private String productCategory;
#Column
private String productDetails;
#Column
private String productPrice;
public VendorDetails getVendordetails() {
return vendordetails;
}
public void setVendordetails(VendorDetails vendordetails) {
this.vendordetails = vendordetails;
}
public int getProductId() {
return productId;
}
public void setProductId(int productId) {
this.productId = productId;
}
public String getProductCategory() {
return productCategory;
}
public void setProductCategory(String productCategory) {
this.productCategory = productCategory;
}
public String getProductDetails() {
return productDetails;
}
public void setProductDetails(String productDetails) {
this.productDetails = productDetails;
}
public String getProductPrice() {
return productPrice;
}
public void setProductPrice(String productPrice) {
this.productPrice = productPrice;
}
}
DAO class ProductDetailDaoImpl.java
package com.cts.Dao;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import com.cts.entity.ProductDetails;
import com.cts.entity.to.ProductDetailsTo;
#Repository
public class ProductDetailDaoImpl implements ProductDetailDao {
#Autowired
SessionFactory sessionFactory;
#Transactional
public boolean saveProductInfo(ProductDetailsTo productTo) {
System.out.println("M in Registration DAO");
System.out.println(productTo.getProductCategory());
System.out.println(productTo.getProductDetails());
System.out.println(productTo.getProductId());
System.out.println(productTo.getProductPrice());
//getting productTo data to entity class
ProductDetails prodet = productTo.getEntity();
System.out.println("Value of product details is:" + prodet.getProductDetails());
sessionFactory.getCurrentSession().save(prodet);
return false;
}
}
VendorDetails has many ProductDetails so you need to make one to many annotation like this:-
#OneToMany(mappedBy="vendordetails") //mappedBy value will be what you declared //in ProductDetails class.
private Collection<ProductDetails> productdetail=new ArrayList<ProductDetails>;
and create the setter and getter of this.
Now in ProductDetails class you need to annotate many to one like this:-
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "VendorId")
private VendorDetails vendordetails;
Then a new column named 'VendorId' will be create in table 'ProductInfo' and since declare mappedBy value="vendordetails" so each vendor id would be insert.
I think you should replace the code
#OneToMany
private ProductDetails productdetail;
to
#OneToMany
private Set productdetailSet;
And create setter and getter for this.
You can visit the blog http://gaurav1216.blogspot.in/2014/01/hibernate-tutorial-day-5.html for one to many using annotation.
This is my annotation class and i want userId and groupId column both as primary key.
I have found more questions (Question) about this, but didn't found relevant answer.
I have less reputation, so I am not able to comment on posts, So I am putting my question here.
This is my code..
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import org.hibernate.annotations.NaturalId;
#Entity
#Table(name="user_group")
public class user_group {
#Column(name="serviceProvider")
private String serviceProvider;
#Column(name="enterpriseId")
private String enterpriseId;
#Column(name="department")
private String department;
#Column(name="trunkGroupName")
private String trunkGroupName;
#Id
#Column(name="userId")
private String userId;
#Column(name="groupId")
private String group;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getGroup() {
return group;
}
public void setGroup(String group) {
this.group = group;
}
public String getServiceProvider() {
return serviceProvider;
}
public void setServiceProvider(String serviceProvider) {
this.serviceProvider = serviceProvider;
}
public String getEnterpriseId() {
return enterpriseId;
}
public void setEnterpriseId(String enterpriseId) {
this.enterpriseId = enterpriseId;
}
public String getDepartment() {
return department;
}
public void setDepartment(String department) {
this.department = department;
}
public String getTrunkGroupName() {
return trunkGroupName;
}
public void setTrunkGroupName(String trunkGroupName) {
this.trunkGroupName = trunkGroupName;
}
}
You should create a new #Embeddable class containing the PK fields:
#Embeddable
public class user_groupId implements Serializable {
#Column(name="userId")
private String userId;
#Column(name="groupId")
private String group;
}
And use it in the #Entity as an #EmbeddedId:
#Entity
public class user_group {
#EmbeddedId
user_groupId id;
...
}
You could also use the #IdClass annotation to that effect.
This excellent answer by Pascal Thivent elaborates on the details. You can also take a look at this other answer I posted to a almost identical question some time ago.
As a side note, if you've got control over the DB structure, you might also consider avoiding composite keys. There are some reasons to do so.
you can create a composite primary key in hibernate using #UniqueConstraint annotation.
#Table(name="user_group",uniqueConstraints=#UniqueConstraint(columnNames= {"userId","groupId"}))
public class user_group
{
#Column(name="userId")
private String userId;
#Column(name="groupId")
private String group;
}
above method is not feasible if we use spring because for creating composite primary key we have to create a class is not a good thing.
in hibernate and spring you only have to create POJO classes which are available as an entity on your system.
I am having some problems getting a larger application with many table relationships working with Struts2 and Hibernate, so I decided to create a much smaller-scale example to figure it out and I cannot get that working either. My main problem is that I cannot get the two to work together at all when there are any lazy instantiation sets involved. I am trying to figure out how to make it work with and without loading the lazy data, but in this case I have loaded the lazy data and I am getting a "java.lang.StackOverflowError." I have two tables, "Departments," with two entries and "Employees," with three; I am using the Struts2 "xslt" result type. Here are the two persistence classes:
Departments:
package com.test.model;
// Generated Apr 7, 2012 7:10:28 PM by Hibernate Tools 3.4.0.CR1
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
/**
* Departments generated by hbm2java
*/
#Entity
#Table(name="Departments"
,catalog="test"
)
public class Departments implements java.io.Serializable {
private Integer id;
private String name;
private Set<Employees> employeeses = new HashSet(0);
public Departments() {
}
public Departments(String name) {
this.name = name;
}
public Departments(String name, Set employeeses) {
this.name = name;
this.employeeses = employeeses;
}
#Id #GeneratedValue(strategy=IDENTITY)
#Column(name="Id", unique=true, nullable=false)
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
#Column(name="Name", nullable=false)
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
#OneToMany(fetch=FetchType.LAZY, mappedBy="departments")
public Set<Employees> getEmployeeses() {
return this.employeeses;
}
public void setEmployeeses(Set employeeses) {
this.employeeses = employeeses;
}
}
Employees:
package com.test.model;
// Generated Apr 7, 2012 7:10:28 PM by Hibernate Tools 3.4.0.CR1
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
/**
* Employees generated by hbm2java
*/
#Entity
#Table(name="Employees"
,catalog="test"
)
public class Employees implements java.io.Serializable {
private Integer id;
private Departments departments;
private String firstName;
private String lastName;
public Employees() {
}
public Employees(Departments departments, String firstName, String lastName) {
this.departments = departments;
this.firstName = firstName;
this.lastName = lastName;
}
#Id #GeneratedValue(strategy=IDENTITY)
#Column(name="Id", unique=true, nullable=false)
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="DepartmentsId", nullable=false)
public Departments getDepartments() {
return this.departments;
}
public void setDepartments(Departments departments) {
this.departments = departments;
}
#Column(name="FirstName", nullable=false)
public String getFirstName() {
return this.firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
#Column(name="LastName", nullable=false)
public String getLastName() {
return this.lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
The HQL query I am using in the DepartmentsManager class is: "from Departments d left join fetch d.employeeses".
Here is the stacktrace of the error:
Exception in thread "http-bio-8080-exec-4" java.lang.StackOverflowError
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.commons.logging.LogFactory.getContextClassLoaderInternal(LogFactory.java:859)
at org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:423)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
at com.opensymphony.xwork2.util.logging.commons.CommonsLoggerFactory.getLoggerImpl(CommonsLoggerFactory.java:29)
at com.opensymphony.xwork2.util.logging.LoggerFactory.getLogger(LoggerFactory.java:42)
at org.apache.struts2.views.xslt.AbstractAdapterNode.(AbstractAdapterNode.java:85)
at org.apache.struts2.views.xslt.AbstractAdapterElement.(AbstractAdapterElement.java:41)
at org.apache.struts2.views.xslt.BeanAdapter.(BeanAdapter.java:73)
at sun.reflect.GeneratedConstructorAccessor14.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at java.lang.Class.newInstance0(Class.java:372)
at java.lang.Class.newInstance(Class.java:325)
at org.apache.struts2.views.xslt.AdapterFactory.constructAdapterInstance(AdapterFactory.java:209)
at org.apache.struts2.views.xslt.AdapterFactory.adaptNode(AdapterFactory.java:159)
at org.apache.struts2.views.xslt.BeanAdapter.buildChildAdapters(BeanAdapter.java:135)
at org.apache.struts2.views.xslt.AbstractAdapterNode.getChildAdapters(AbstractAdapterNode.java:128)
at org.apache.struts2.views.xslt.AbstractAdapterNode.getChildNodes(AbstractAdapterNode.java:186)
at org.apache.struts2.views.xslt.BeanAdapter.getChildNodes(BeanAdapter.java:88)
at org.apache.struts2.views.xslt.AbstractAdapterNode.getFirstChild(AbstractAdapterNode.java:194)
at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2SAX.parse(DOM2SAX.java:300)
at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2SAX.parse(DOM2SAX.java:302)...[this line repeats ad nauseam]
Would someone please point me in the right direction?
Thanks!
Yes, here's a thought:
You have a Departments class (bad naming - use the singular Department). It has a Set of Employee instances. It's a one to many relationship: a Department can have one or more Employees. So far, so good.
Your Employees class (more bad naming - use the singular Employee) has a reference to its parent Department.
You see the problem? Every time you call the Employee constructor, you can the Department constructor, which creates a Set of Employees. The instance of the original Employee is in that Set, which again calls the Department constructor, ad nauseum.
You need to break the cycle: it's a bidirectional one-to-many:
http://docs.jboss.org/hibernate/orm/3.3/reference/en/html/example-parentchild.html#example-parentchild-bidir
I am creating a website that will have articles; each article will have comments. These comments will be stored in a "comment" table with a field called "parent_id" that is a foreign key to the field "id" in the same table.
I am hoping to use Hibernate to recursively grab all of the comments for a specific article.
Here is my Entity:
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import org.hibernate.annotations.IndexColumn;
#Entity
public class Comment implements Serializable {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
#ManyToOne
#JoinColumn(name="user_id")
private User user;
#OneToMany(targetEntity=Comment.class)
#JoinColumn(name="parent_id")
#IndexColumn(name="id", base=0)
private List<Comment> comments = new ArrayList<Comment>();
#Column(name="article_id", length=10)
private int articleId;
#Column(name="text", length=8192)
private String text;
public int getArticleId() {
return articleId;
}
public void setArticleId(int articleId) {
this.articleId = articleId;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
#Override
public String toString() {
return "Comment [" + "articleId " + articleId + " " + "id " + id + " " + "text " + text + " " + "]";
}
}
The code is "kinda" working, however, when all of the comments are retrieved the "child" list of comments contains the same number of elements as there are total comments (if that makes sense. For instance, assume I have only three comments in the table for article with id number 1... this article with 2 comments, and one of the comments has a child comment.. the array with the child comment has 3 entries, the first 2 are null and the last is the child comment.
Is this code correct?
I wonder if the problem is not coming from the fact that you are using the PK column as index column. I'd recommend to use a dedicated column for the index column. Something like this:
#OneToMany
#JoinColumn(name="parent_id")
#IndexColumn(name="comments_index", base=0)
private List<Comment> comments = new ArrayList<Comment>();
Could you give this a try?