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  • Date query with Hibernate on Timestamp Column in PostgreSQL

    - by Shashikant Kore
    A table has timestamp column. A sample value in that could be 2010-03-30 13:42:42. With Hibernate, I am doing a range query Restrictions.between("column-name", fromDate, toDate). The Hibernate mapping for this column is as follows. <property name="orderTimestamp" column="order_timestamp" type="java.util.Date" /> Let's say, I want to find out all the records that have the date 30th March 2010 and 31st March 2010. A range query on this field is done as follows. Date fromDate = new SimpleDateFormat("yyyy-MM-dd").parse("2010-03-30"); Date toDate = new SimpleDateFormat("yyyy-MM-dd").parse("2008-03-31"); Expression.between("orderTimestamp", fromDate, toDate); This doesn't work. The query is converted to respective timestamps as "2010-03-30 00:00:00" and "2010-03-31 00:00:00". So, all the records for the 31st March 2010 are ignored. A simple solution to this problem could be to have the end date as "2010-03-31 23:59:59." But, I would like to know if there is way to match only the date part of the timestamp column. Also, is Expression.between() inclusive of both limits? Documentation doesn't throw any light on this.

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  • Hibernate bit array to entity mapping

    - by teabot
    I am trying to map a normalized Java model to a legacy database schema using Hibernate 3.5. One particular table encodes a foreign keys in a one-to-many relationship as a bit array column. Consider tables 'person' and 'clubs' that describes people's affiliations to clubs: person .----.------. club: .----.---------.---------------------------. | id | name | | id | name | members | binary(members) | |----+------| |----+---------|---------+-----------------| | 1 | Bob | | 10 | Cricket | 0 | 000 | | 2 | Joe | | 11 | Tennis | 5 | 101 | | 3 | Sue | | 12 | Cooking | 7 | 111 | '----'------' | 13 | Golf | 3 | 100 | '----'---------'---------'-----------------' So hopefully it is clear that person.id is used as the bit index in the bit array club.members. In this example the members column tells us that: no one is a member of Cricket, Bob/Sue - Tennis, Bob/Sue/Joe - Cooking and Sue - Golf. In my Java domain I'd like to declare this with entities like so: class Person { private int id; private String name; ... } class Club { private Set<Person> members; private int id; private String name; ... } I am assuming that I must use a UserType implementation but have been unable to find any examples where the items described by the user type are references to entities - not literal field values - or composites thereof. Additionally I am aware that I'll have to consider how the person entities are fetched when a club instance is loaded. Can anyone tell me how I can tame this legacy schema with Hibernate?

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  • Hibernate one-to-one mapping

    - by Andrey Yaskulsky
    I have one-to-one hibernate mapping between class Student and class Points: @Entity @Table(name = "Users") public class Student implements IUser { @Id @Column(name = "id") private int id; @Column(name = "name") private String name; @Column(name = "password") private String password; @OneToOne(fetch = FetchType.EAGER, mappedBy = "student") private Points points; @Column(name = "type") private int type = getType(); //gets and sets... @Entity @Table(name = "Points") public class Points { @GenericGenerator(name = "generator", strategy = "foreign", parameters = @Parameter(name = "property", value = "student")) @Id @GeneratedValue(generator = "generator") @Column(name = "id", unique = true, nullable = false) private int Id; @OneToOne @PrimaryKeyJoinColumn private Student student; //gets and sets And then i do: Student student = new Student(); student.setId(1); student.setName("Andrew"); student.setPassword("Password"); Points points = new Points(); points.setPoints(0.99); student.setPoints(points); points.setStudent(student); Session session = HibernateUtil.getSessionFactory().getCurrentSession(); session.beginTransaction(); session.save(student); session.getTransaction().commit(); And hibernate saves student in the table but not saves corresponding points. Is it OK? Should i save points separately?

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  • Hibernate : Opinions in Composite PK vs Surrogate PK

    - by Albert Kam
    As i understand it, whenever i use @Id and @GeneratedValue on a Long field inside JPA/Hibernate entity, i'm actually using a surrogate key, and i think this is a very nice way to define a primary key considering my not-so-good experiences in using composite primary keys, where : there are more than 1 business-value-columns combination that become a unique PK the composite pk values get duplicated across the table details cannot change the business value inside that composite PK I know hibernate can support both types of PK, but im left wondering by my previous chats with experienced colleagues where they said that composite PK is easier to deal with when doing complex SQL queries and stored procedure processes. They went on saying that when using surrogate keys will complicate things when doing joining and there are several condition when it's impossible to do some stuffs when using surrogate keys. Although im sorry i cant explain the detail here since i was not clear enough when they explain it. Maybe i'll put more details next time. Im currently trying to do a project, and want to try out surrogate keys, since it's not getting duplicated across tables, and we can change the business-column values. And when the need for some business value combination uniqueness, i can use something like : @Table(name="MY_TABLE", uniqueConstraints={ @UniqueConstraint(columnNames={"FIRST_NAME", "LAST_NAME"}) // name + lastName combination must be unique But im still in doubt because of the previous discussion about the composite key. Could you share your experiences in this matter ? Thank you !

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  • Understanding Hibernate saveOrUpdate

    - by Stephano
    The books that I've read regarding hibernate are, at best, reference tomes. They very seldom have good code examples, so I tend to use online resources for those needs. However, I've always had a problem understanding the basic idea of hibernate persistence. I've read the books and understand the concepts, but in practice, I often see results that I don't understand. Perhaps you all can help, as you have in the past. Let's look at a simple example of a dog and a cat that are friends. This isn't a rare occurrence. It also has the benefit of being much more interesting than my business case. We want a function called "saveFriends" that takes a dog name and a cat name. We'll save the Dog and then the Cat. For this example to work, the cat is going to have a reference back to the dog. I understand this isn't an ideal example, but it's cute and works for our purposes. FriendService.java public int saveFriends(String dogName, String catName) { Dog fido = new Dog(); Cat felix = new Cat(); fido.name = dogName; fido = animalDao.saveDog(fido); felix.name = catName; [ex.A]felix.friend = fido; [ex.B]felix.friend = animalDao.getDogByName(dogName); animalDao.saveCat(felix); } AnimalDao.java (extends HibernateDaoSupport) public Dog saveDog(Dog dog) { getHibernateTemplate().saveOrUpdate(dog); return dog } public Cat saveCat(Cat cat) { getHibernateTemplate().saveOrUpdate(cat); return cat; } public Dog getDogByName(String name) { return (Dog) getHibernateTemplate().find("from Dog where name=?", name).get(0); } Now, assume for a minute that I would like to use either example A or example B to save my friend. Is one better than the other to use? I'll understand if neither of those examples work, but please explain why.

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  • Help regarding composite pattern with hibernate

    - by molleman
    Hello, So i am stuck, i am creating a gwt web application, i will be using a tree(gwt Tree and TreeItems) structure to show a list of folders(class Folder) and files(class FileLocation), the folder and filelocation class will all implement a Hierarchy interface basing the classes on the composite pattern. but i am using hibernate to store my data , and i am using annotations for the mapping of the data to the database. my trouble is i do not know how to annotate my interface. have any of you guys used the composite pattern while persisting the data with hibernate public interface Hierarchy(){ // a few abstract methods that will be implemented by the sub classes } @Entity @Table() public class Folder extends Hierarchy implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "folder_id", updatable = false, nullable = false) private int id; @OneToMany(cascade = CascadeType.ALL,fetch = FetchType.EAGER) @JoinTable(name = "FOLDER_FILELOCATION", joinColumns = { @JoinColumn(name = "folder_id") }, inverseJoinColumns = { @JoinColumn(name = "file_information_id") }) private List<Hierarchy> children = new ArrayList<Hierarchy>() ; @Column(name = "folder_name") private String folderName; @Column(name = "tree_item") private TreeItem item; @Column (name = "parent") private Hierarchy parent; @Entity @Table(name = "FILE_INFORMATION_TABLE") public class FileInformation extends Hierarchy implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "file_information_id", updatable = false, nullable = false) private int fiId; @Column (name = "location") private String location; @Column(name = "tree_item") private TreeItem item; @Column (name = "parent") private Hierarchy parent;

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  • Spring configuration of C3P0 with Hibernate?

    - by HDave
    I have a Spring/JPA application with Hibernate as the JPA provider. I've configured a C3P0 data source in Spring via: <bean id="myJdbcDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <!-- Connection properties --> <property name="driverClass" value="$DS{database.class}" /> <property name="jdbcUrl" value="$DS{database.url}" /> <property name="user" value="$DS{database.username}" /> <property name="password" value="$DS{database.password}" /> <!-- Pool properties --> <property name="minPoolSize" value="5" /> <property name="maxPoolSize" value="20" /> <property name="maxStatements" value="50" /> <property name="idleConnectionTestPeriod" value="3000" /> <property name="loginTimeout" value="300" /> I then specified this data source in the Spring entity manager factory as follows: <bean id="myLocalEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="myapp-core" /> <property name="dataSource" ref="myJdbcDataSource" /> </bean> However, I recently noticed while browsing maven artifacts a "hibernate-c3p0". What is this? Is this something I need to use? Or do I already have this configured properly?

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  • Hibernate ManyToMany and superclass mapping problem

    - by Jesus Benito
    Hi all, I need to create a relation in Hibernate, linking three tables: Survey, User and Group. The Survey can be visible to a User or to a Group, and a Group is form of several Users. My idea was to create a superclass for User and Group, and create a ManyToMany relationship between that superclass and Survey. My problem is that Group, is not map to a table, but to a view, so I can't split the fields of Group among several tables -which would happen if I created a common superclass-. I thought about creating a common interface, but mapping to them is not allowed. I will probably end up going for a two relations solution (Survey-User and Survey-Group), but I don't like too much that approach. I thought as well about creating a table that would look like: Survey Id | ElementId | Type ElementId would be the Group or UserId, and the type... the type of it. Does anyone know how to achieve it using hibernate annotations? Any other ideas? Thanks a lot

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  • [hibernate - jpa] @CollectionOfElements without create the apposite table

    - by blow
    Hi all. I have this: Municipality class @Entity public class Municipality implements Serializable { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; private String country; private String province; private String name; @Column(name="cod_catasto") private String codCatastale; private String cap; @CollectionOfElements private List<Address> addressList; public Municipality() { } ... Address class @Embeddable public class Address implements Serializable { @ManyToOne(fetch=FetchType.LAZY) @Cascade(CascadeType.SAVE_UPDATE) private Municipality municipality; @Column(length=45) private String address; public Address() { } ... Address is embedded in another class Person. When i save an instance of Person, hibernate create 3 tables: PERSON, MUNICIPALITY and MUNICIPALITY_ADDRESSLIST. MUNICIPALITY_ADDRESSLIST contains 2 fields: MUNICIPALITY_ID (FK) and STREET. I don't want this table, i only want the ID of table MUNICIPALITY into table PERSON(that embeds Address), what should i do? I tried to add @JoinTable in Municipality entity like this: @CollectionOfElements @JoinTable(name="person") private List<Address> addressList; It partially worked, but i cant choose the column name of table PERSON that contains ID of the table MUNICIPALITY, it is, by hibernate choose, simply "MUNICIPALITY_ID"... Thbaks.

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  • Modeling multiple polymorphic relationships using Hibernate

    - by f-potter
    Ruby on Rails has polymorphic relations which are really useful for implementing functionality such as commenting, tagging and rating to name a few. We can have a comment, tag or rating class which has a many to one polymorphic relationship with a commentable, taggable and rateable object. Also, a given domain object can choose to implement any combination of such relations. So, it can for example be commentable, taggable and rateable at the same time. I couldn't think up of a straightforward way to duplicate this functionality in Hibernate. Ideally, there would be a Comment class which will have a many to one relationship with a Commentable class and a Commentable class will conversely have a one to many relationship with Comments. It will be ideal if the concrete domain classes can inherit from a number of such classes, say Commentable and Taggable. Things seem a little complicated as a Java class can only extend one other class and some code might end up being duplicated across a number of classes. I wanted to know what are the best practices for modeling such relationships neatly and concisely using Hibernate?

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  • Hibernate query for multiple items in a collection

    - by aarestad
    I have a data model that looks something like this: public class Item { private List<ItemAttribute> attributes; // other stuff } public class ItemAttribute { private String name; private String value; } (this obviously simplifies away a lot of the extraneous stuff) What I want to do is create a query to ask for all Items with one OR MORE particular attributes, ideally joined with arbitrary ANDs and ORs. Right now I'm keeping it simple and just trying to implement the AND case. In pseudo-SQL (or pseudo-HQL if you would), it would be something like: select all items where attributes contains(ItemAttribute(name="foo1", value="bar1")) AND attributes contains(ItemAttribute(name="foo2", value="bar2")) The examples in the Hibernate docs didn't seem to address this particular use case, but it seems like a fairly common one. The disjunction case would also be useful, especially so I could specify a list of possible values, i.e. where attributes contains(ItemAttribute(name="foo", value="bar1")) OR attributes contains(ItemAttribute(name="foo", value="bar2")) -- etc. Here's an example that works OK for a single attribute: return getSession().createCriteria(Item.class) .createAlias("itemAttributes", "ia") .add(Restrictions.conjunction() .add(Restrictions.eq("ia.name", "foo")) .add(Restrictions.eq("ia.attributeValue", "bar"))) .list(); Learning how to do this would go a long ways towards expanding my understanding of Hibernate's potential. :)

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  • Saving owned/child objects in Hibernate

    - by maxdj
    I'm having a hard time wrapping my head around the way hibernate objects work. Here's a little chunk of what my model looks like: JobOpening: @ManyToMany(fetch=FetchType.EAGER,cascade=CascadeType.ALL) @JoinTable( name="jobOpening_questionSet", joinColumns=@JoinColumn(name="jobOpenings_id"), inverseJoinColumns=@JoinColumn(name="questionSets_id") ) @IndexColumn(name="question_sets_idx",base=0,nullable=false) public List<QuestionSet> getQuestionSets() { return questionSets; } QuestionSet: @ManyToMany(mappedBy="questionSets",fetch=FetchType.EAGER) public Set<JobOpening> getJobOpenings() { return jobOpenings; } @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.EAGER) @IndexColumn(name="questions_idx",base=0) @JoinColumn(name="questionset_id",nullable=false) public List<FormQuestion> getQuestions() { return questions; } FormQuestion: @ManyToOne @JoinColumn(name="questionset_id", insertable=false, updatable=false, nullable=false) @OnDelete(action=OnDeleteAction.CASCADE) public QuestionSet getQuestionSet() { return questionSet; } Now how would I go about, say, modifying a question in the question set, or changing which jobs a questionset is associated with? For example, to edit a question in a questionset, I imagine I should be able to just get the question via its id, change some values, and merge() it back in, but this doesn't work. I'm using Hibernate from Spring (appfuse), usually as detached objects.

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  • Spring MVC + Hibernate encoding problem

    - by Bar
    I work on Spring MVC + Hibernate application, use MySQL (ver. 5.0.51a) with the InnoDB engine. The problem appears when I am sending a form with cyrillic characters. As the result, database contains senseless chars in unknown encoding. All the JSP pages, database (+ tables and fields) created using UTF-8. Hibernate config also contains property which sets encoding to UTF-8. I had solved this by creating filter which encodes request content with UTF-8. Exemplary code: … encoding = "UTF-8"; request.setCharacterEncoding(encoding); chain.doFilter(request, response); … But it visibly slows down the app. The interesting thing is that executing insert query directly from the app (i.e. running from Eclipse as Java Application) works perfect. Any suggestions are welcome. TIA, Michael.

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  • Reverse search in Hibernate Search

    - by Javi
    Hello, I'm using Hibernate Search (which uses Lucene) for searching some Data I have indexed in a directory. It works fine but I need to do a reverse search. By reverse search I mean that I have a list of queries stored in my database I need to check which one of these queries match with a Data object each time Data Object is created. I need it to alert the user when a Data Object matches with a Query he has created. So I need to index this single Data Object which has just been created and see which queries of my list has this object as a result. I've seen Lucene MemoryIndex Class to create an index in memory so I can do something like this example for every query in a list (though iterating in a Java list of queries would not be very efficient): //Iterating over my list<Query> MemoryIndex index = new MemoryIndex(); //Add all fields index.addField("myField", "myFieldData", analyzer); ... QueryParser parser = new QueryParser("myField", analyzer); float score = index.search(query); if (score > 0.0f) { System.out.println("it's a match"); } else { System.out.println("no match found"); } The problem here is that this Data Class has several Hibernate Search Annotations @Field,@IndexedEmbedded,... which indicated how fields should be indexed, so when I invoke index() method on the FullTextEntityManager instance it uses this information to index the object in the directory. Is there a similar way to index it in memory using this information? Is there a more efficient way of doing this reverse search? Thanks

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  • Maven Java Source Code Generation for Hibernate

    - by Adam
    Hi, I´m busy converting an existing project from an Ant build to one using Maven. Part of this build includes using the hibernate hbm2java tool to convert a collection of .hbm.xml files into Java. Here's a snippet of the Ant script used to do this: <target name="dbcodegen" depends="cleangen" description="Generate Java source from Hibernate XML"> <hibernatetool destdir="${src.generated}"> <configuration> <fileset dir="${src.config}"> <include name="**/*.hbm.xml"/> </fileset> </configuration> <hbm2java jdk5="true"/> </hibernatetool> </target> I've had a look around on the internet and some people seem to do this (I think) using Ant within Maven and others with the Maven plugin. I'd prefer to avoid mixing Ant and Maven. Can anyone suggest a way to do this so that all of the .hbm.xml files are picked up and the code generation takes place as part of the Maven code generation build phase? Thanks! Adam.

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  • JPA 2.0 Provider Hibernate

    - by Rooh
    I have very strange problem we are using jpa 2.0 with hibernate annotations based Database generated through JPA DDL is true and MySQL as Database; i will provide some reference classes and then my porblem. @MappedSuperclass public abstract class Common implements serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; @ManyToOne @JoinColumn private Address address; //with all getter and setters //as well equal and hashCode } @Entity public class Parent extends Common{ private String name; @OneToMany(cascade = {CascadeType.MERGE,CascadeType.PERSIST}, mappedBy = "parent") private List<Child> child; //setters and rest of class } @Entity public class Child extends Common{ //some properties with getter/setters } @Entity public class Address implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; private String street; //rest of class with get/setter } as in code you can see that parents and child classes extends Common class so both have address property and id , the problem occurs when change the address refference in parent class it reflect same change in all child objects in list and if change address refference in child class then on merge it will change address refference of parent as well i am not able to figure out is it is problem of jpa or hibernate

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  • Hibernate collection mapping challenge

    - by Geln Yang
    Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two character of its code : class Item{ string code; string name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <!--====================================== --> <many-to-one name="parent" class="Item" not-found="ignore"></many-to-one> <bag name="children"></bag> <!--====================================== --> </class> </hibernate-mapping> How to definition the mapping relationship? Thanks!

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  • What is best practice about having one-many hibernate

    - by Patrick
    Hi all, I believe this is a common scenario. Say I have a one-many mapping in hibernate Category has many Item Category: @OneToMany( cascade = {CascadeType.ALL},fetch = FetchType.LAZY) @JoinColumn(name="category_id") @Cascade( value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN ) private List<Item> items; Item: @ManyToOne(targetEntity=Category.class,fetch=FetchType.EAGER) @JoinColumn(name="category_id",insertable=false,updatable=false) private Category category; All works fine. I use Category to fully control Item's life cycle. But, when I am writing code to update Category, first I get Category out from DB. Then pass it to UI. User fill in altered values for Category and pass back. Here comes the problem. Because I only pass around Category information not Item. Therefore the Item collection will be empty. When I call saveOrUpdate, it will clean out all associations. Any suggestion on what's best to address this? I think the advantage of having Category controls Item is to easily main the order of Item and not to confuse bi-directly. But what about situation that you do want to just update Category it self? Load it first and merge? Thank you.

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  • Hibernate collection mapping Problem

    - by Geln Yang
    Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two characters of its code : class Item{ String code; String name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <many-to-one name="parent" class="Item" not-found="ignore"> <formula> <![CDATA[ (select i.code,r.name from Item i where (case length(code) when 4 then i.code=SUBSTRING(code,1,2) else false end)) ]]> </formula> </many-to-one> <bag name="children"></bag> </class> </hibernate-mapping> I try to use formula to define the many-to-one relationship,but it doesn't work!Is there something wrong?Or is there other method? Thanks! ps,I use mysql database.

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  • Understanding Hibernate saveOrUpdate and the Persistence Life Cycle

    - by Stephano
    The books that I've read regarding hibernate are, at best, reference tomes. They very seldom have good code examples, so I tend to use online resources for those needs. However, I've always had a problem understanding the basic idea of hibernate persistence. I've read the books and understand the concepts, but in practice, I often see results that I don't understand. Perhaps you all can help, as you have in the past. Let's look at a simple example of a dog and a cat that are friends. This isn't a rare occurrence. It also has the benefit of being much more interesting than my business case. We want a function called "saveFriends" that takes a dog name and a cat name. We'll save the Dog and then the Cat. For this example to work, the cat is going to have a reference back to the dog. I understand this isn't an ideal example, but it's cute and works for our purposes. FriendService.java public int saveFriends(String dogName, String catName) { Dog fido = new Dog(); Cat felix = new Cat(); fido.name = dogName; fido = animalDao.saveDog(fido); felix.name = catName; [ex.A]felix.friend = fido; [ex.B]felix.friend = animalDao.getDogByName(dogName); animalDao.saveCat(felix); } AnimalDao.java (extends HibernateDaoSupport) public Dog saveDog(Dog dog) { getHibernateTemplate().saveOrUpdate(dog); return dog } public Cat saveCat(Cat cat) { getHibernateTemplate().saveOrUpdate(cat); return cat; } public Dog getDogByName(String name) { return (Dog) getHibernateTemplate().find("from Dog where name=?", name).get(0); } Now, assume for a minute that I would like to use either example A or example B to save my friend. Is one better than the other to use? I'll understand if neither of those examples work, but please explain why.

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  • Hibernate collection multiple types

    - by CaptainAwesomePants
    I have a class Player that contains a list of Accessory objects. There are two kinds of Accessories. SocketedAccessories have a list of SocketJewels, and MagicAccessories have a list of MagicEnchantments. At the database level, there is a players table that represents the player, and an accessories table that contains a list of accessories. Accessories have a type field that indicates whether they are socketed or magical, and the columns that are only used by one type are just left blank by entries of the other type. There are socket_jewels and magic_enchantments tables, representing the socket jewels or the magic enchantments on each accessory. I am trying to figure out the correct way to map this with Hibernate. One way would be for the player to have two lists of accessories, one for SocketedAccessories and one for MagicAccessories. That seems undesirable, though. What I want is a way to specify that player should have a field List<Accessory> accessories that contains both types of thing. Is there a way to tell Hibernate, in either hbm.xml or annotations, to do this?

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  • Object equality in context of hibernate / webapp

    - by bert
    How do you handle object equality for java objects managed by hibernate? In the 'hibernate in action' book they say that one should favor business keys over surrogate keys. Most of the time, i do not have a business key. Think of addresses mapped to a person. The addresses are keeped in a Set and displayed in a Wicket RefreshingView (with a ReuseIfEquals strategy). I could either use the surrogate id or use all fields in the equals() and hashCode() functions. The problem is that those fields change during the lifetime ob the object. Either because the user entered some data or the id changes due to JPA merge() being called inside the OSIV (Open Session in View) filter. My understanding of the equals() and hashCode() contract is that those should not change during the lifetime of an object. What i have tried so far: equals() based on hashCode() which uses the database id (or super.hashCode() if id is null). Problem: new addresses start with an null id but get an id when attached to a person and this person gets merged() (re-attached) in the osiv-filter. lazy compute the hashcode when hashCode() is first called and make that hashcode @Transitional. Does not work, as merge() returns a new object and the hashcode does not get copied over. What i would need is an ID that gets assigned during object creation I think. What would be my options here? I don't want to introduce some additional persistent property. Is there a way to explicitly tell JPA to assign an ID to an object? Regards

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  • Hibernate mapping Problem

    - by Geln Yang
    Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two characters of its code : class Item{ String code; String name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <many-to-one name="parent" class="Item" not-found="ignore"> <formula> <![CDATA[ (select i.code,r.name from Item i where (case length(code) when 4 then i.code=SUBSTRING(code,1,2) else false end)) ]]> </formula> </many-to-one> <bag name="children"></bag> </class> </hibernate-mapping> I try to use formula to define the many-to-one relationship,but it doesn't work!Is there something wrong?Or is there other method? Thanks! ps,I use mysql database.

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  • JPA/Hibernate Parent/Child relationship

    - by NubieJ
    Hi I am quite new to JPA/Hibernate (Java in general) so my question is as follows (note, I have searched far and wide and have not come across an answer to this): I have two entities: Parent and Child (naming changed). Parent contains a list of Children and Children refers back to parent. e.g. @Entity public class Parent { @Id @Basic @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "PARENT_ID", insertable = false, updatable = false) private int id; /* ..... */ @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.LAZY) @JoinColumn(name = "PARENT_ID", referencedColumnName = "PARENT_ID", nullable = true) private Set<child> children; /* ..... */ } @Entity public class Child { @Id @Basic @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "CHILD_ID", insertable = false, updatable = false) private int id; /* ..... */ @ManyToOne(cascade = { CascadeType.REFRESH }, fetch = FetchType.EAGER, optional = false) @JoinColumn(name = "PARENT_ID", referencedColumnName = "PARENT_ID") private Parent parent; /* ..... */ } I want to be able to do the following: Retrieve a Parent entity which would contain a list of all its children (List), however, when listing Parent (getting List, it of course should omit the children from the results, therefore setting FetchType.LAZY. Retrieve a Child entity which would contain an instance of the Parent entity. Using the code above (or similar) results in two exceptions: Retrieving Parent: A cycle is detected in the object graph. This will cause infinitely deep XML... Retrieving Child: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: xxxxxxxxxxx, no session or session was closed When retrieving the Parent entity, I am using a named query (i.e. calling it specifically) @NamedQuery(name = "Parent.findByParentId", query = "SELECT p FROM Parent AS p LEFT JOIN FETCH p.children where p.id = :id") Code to get Parent (i.e. service layer): public Parent findByParentId(int parentId) { Query query = em.createNamedQuery("Parent.findByParentId"); query.setParameter("id", parentId); return (Parent) query.getSingleResult(); } Why am I getting a LazyInitializationException event though the List property on the Parent entity is set as Lazy (when retrieving the Child entity)?

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  • Java-Hibernate: How can I translate these tables to hibernate annotations?

    - by penas
    I need to create a simple application using these tables: http://stackoverflow.com/questions/2612848/are-these-tables-respect-the-3nf-database-normalization I have created the application using simple old JDBC, but I would like to see how the application would look like using Hibernate, but I don't know how to put the sql code in java. I have found LOTS of examples, but I'm pretty much confused about using Hibernate and I don't know If I made such a good joob. For example, for the first three tables: AUTHOR table * Author_ID, PK * First_Name * Last_Name TITLES table * TITLE_ID, PK * NAME * Author_ID, FK DOMAIN table * DOMAIN_ID, PK * NAME * TITLE_ID, FK The code in java: Table 1 @Entity @Table(name = "AUTHORS", schema = "LIBRARY") public class Author{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "Author_ID") private int authorId; @Column(name = "First_Name", nullable = false, length = 50) private String firstName; @Column(name = "Last_Name", nullable = false, length = 40) private String lastName; @OneToMany @JoinColumn(name = "Title_ID") private List<Title> titles; Table 2 @Entity @Table(name = "TITLES") public class Title{ @Id @Column(name = "Title_ID") private int titleID; @Column(name = "Name", nullable = false, length = 50) private String name; @ManyToOne @JoinColumn(name = "Domain_ID") private Domain domains; Table 3 @Entity @Table(name = "DOMAINS") public class Domain{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "Domain_ID") private int Domain_ID; @Column(name = "Name", nullable = false, length = 50) private String name; @OneToOne(mappedBy = "domains") private Title title; } Any good? :)

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