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  • how to implement inheritance in hibernate ??

    - by user359057
    Hi guys i am working in a web application. I have a entities as BaseEntity --Which contains user login info like createdBy,createdTime,EditedBy,editedTime Employee -- which contains employee information like name,address,etc... RegularEmployee --which contains salary ,bonus tht kind of fields and ContactEmployee -- which contains HourlyRate,contactPeriod etc.... My inheritance structure is BaseEntity <--- Employee <---- RegularEmployee (i.e. Employee extends BaseEntity and RegularEmployee extends Employee ContractEmployee also extend Employee Class ). How to design database structure in this case considering all the tables have id and version fields (all tables should at least have these two fields).

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  • Hibernate reverse engineering

    - by EugeneP
    I have a structure where the main table is USER, other tables include CATEGORY (contains user_id). What I got after the standard reverse engineering procedure was: the class User contained a collection of categories, the class Category didn't contain the foreign key (user_id) but it did contain the User object. Why did it not contain the foreign key as a class property? And how do I join these two tables in HQL without that glue? HQL - please explain this part.

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  • Hibernate Criteria API: get n random rows

    - by hadrien
    I can't figure out how to fetch n random rows from a criteria instance: Criteria criteria = session.createCriteria(Table.class); criteria.add(Restrictions.eq('fieldVariable', anyValue)); ... Then what? I can't find any doc with Criteria API Does it mean I should use HQL instead? Thanx! EDIT: I get the number of rows by: int max = criteria.setProjecxtion(Projections.rowCount()).uniqueResult(); How do I fetch n random rows with indexes between 0 and max? Thx again!

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  • hibernate many to many only save the new object and between table

    - by Joe
    I have the following tables: Student Student_Course Course Now when I create a student I only want to create a user and add a row to student_course. The "problem" I have is that when I set the set of courses in Student to cascade="save-update" that an update is also invoked on course. I was wondering if there was a way to prevent this.

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  • Hibernate violation error

    - by sarah
    Hi All, I am having a designation table with d_name as primary key which i am using in user table as foreign key reference .I am using hbm for mapping in designation hbm i have id defined as d_name mapped to database column .I am getting a error saying "integrity constraint violation(user_designation_fk) parent key not found. " Where am i going wrong /this error is coming while i am tring to add a user selecting a designation reading from designation table.

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  • hibernate proxy ..

    - by abc
    load() just returns a proxy by default and database won’t be hit until the proxy is first invoked. what does it mean by proxy exactly here ?

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  • Hibernate many-to-many relationship

    - by Capitan
    I have two mapped types, related many-to-many. @Entity @Table(name = "students") public class Student{ ... @ManyToMany(fetch = FetchType.EAGER) @JoinTable( name = "students2courses", joinColumns = { @JoinColumn( name = "student_id", referencedColumnName = "_id") }, inverseJoinColumns = { @JoinColumn( name = "course_id", referencedColumnName = "_id") }) public Set<Course> getCourses() { return courses; } public void setCourses(Set<Course> courses) { this.courses = courses; } ... } __ @Entity @Table(name = "courses") public class Course{ ... @ManyToMany(fetch = FetchType.EAGER, mappedBy = "courses") public Set<Student> getStudents() { return students; } public void setStudents(Set<Student> students) { this.students = students; } ... } But if I update/delete Course entity, records are not created/deleted in table students2courses. (with Student entity updating/deleting goes as expected) I wrote abstract class HibObject public abstract class HibObject { public String getRemoveMTMQuery() { return null; } } which is inherited by Student and Course. In DAO I added this code (for delete() method): String query = obj.getRemoveMTMQuery(); if (query != null) { session.createSQLQuery(query).executeUpdate(); } and I ovrerided method getRemoveMTMQuery() for Course @Override @Transient public String getRemoveMTMQuery() { return "delete from students2courses where course_id = " + id + ";"; } Now it works but I think it's a bad code. Is there a best way to solve this problem?

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  • How to make NOT IN statement via Restrictions

    - by slavig
    I used this trick: List statuses = new ArrayList(); Criteria criteria = session.createCriteria(MessageQueue.class); criteria.add(Restrictions.not(Restrictions.in("message_status", statuses))); and this code creates: ...from MESSAGE_QUEUE mq where not (mq.message_status in (?, ?, ?, ?))... but I need: ...from MESSAGE_QUEUE mq where mq.message_status NOT IN (?, ?, ?, ?) Du you think they are equal statements?

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  • Confused about distinct/aggregate queries with (N)Hibernate

    - by nw
    I'm not sure how to approach queries that don't map 1:1 to my persistent entities - in other words, distinct and aggregate queries. For example, I need to retrieve a distinct list of property values for populating a drop-down list. Should I write a class and a mapping for the "entities" that are returned by this query? Or should I just use the native DB provider and work with native data sets instead?

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  • hibernate validationQuery.. proper way to use it

    - by cometta
    sometime the connection from application to database will drop and i get SQLState: 08006 error Code: 17002. Below is my configuration for database pooling <prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.use_sql_comments">true</prop> <prop key="hibernate.cglib.use_reflection_optimizer">true</prop> <!-- true ==start up slower, but performacen on runtime good--> <prop key="hibernate.hbm2ddl.auto">update</prop> <prop key="hibernate.c3p0.min_size">5</prop> <prop key="hibernate.c3p0.max_size">20</prop> <prop key="hibernate.c3p0.timeout">1800</prop> <prop key="hibernate.c3p0.max_statements">100</prop> <!-- c3p0's PreparedStatement cache. Zero means statement caching is turned off. --> Can anyone advise, should i use validationQuery, onBorrow.. and why need to use it? what other properties should i use to enhance stability of the connection from my application to oracle10g?

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  • Technology Selection for a dynamic product

    - by Kuntal Shah
    We are building a product for Procurement Domain in JAVA. Following are the main technical requirements. Platform Independent Database Independent Browser Independent In functional requirements the product is very dynamic in nature. The main reason being the procurement process around the world is different from client to client. Briefly we need to have a dynamic workflow engine and a dynamic template engine. The workflow engine by which we can define any kind of workflows and the template engine allows us to define any kind of data structures and based on definition it can get the user input through workflow. We have been developing this product for almost 2 years. It has been a long time till we can get down with the dynamics of requirements. Till now we have developed a basic workflow and template engine and which is in use at one of the client. We have been using following technologies. GWT-Ext (Front End Framework) Hibernate (Database Layer) In between we have faced some issues with GWT-Ext (mainly browser compatibility) and database optimization due to sub classing in hibernate. For resolving GWT-Ext issue, which a dying community so we decided to move to SmartGWT. In SmartGWT we faced issues related to loading and now we are able to finalize that GWT 2.3 will be the way to go as the library is rich and performance is upto the mark. We are able to almost finalize GWT-Spring based front and middle layer. In hibernate, we found main issues with sub-classing due to that it was throwing astronomical queries and sometimes it would stop firing any queries for 5-10 seconds or may be around 30 seconds and then resume again. Few days back I came to one article related to ORM. I am a traditional .Net SQL developer and I have always worked with relational database. Reading through this article, I also found it relating to the issues I face. I am still not completely convinced of using hibernate and this article just supported my opinion. Following are the questions for which I am looking for an answer. Should we be going with Hibernate in case of dynamic database requirements and the load of the data will be heavy in future? How can we partition the data, how we can efficiently join the data, how we can optimize the queries? If the answer is no then how do we achieve database independence? Is our choice related to GWT and Spring proper or do we need to change that too? Should we use any other key value pair database if the data is dynamic in nature and it is very difficult to make it relational?

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  • Hibernate: Perform criteria query with Sub-Select AND Left-Outer join?

    - by Markos Fragkakis
    Can I perform a Criteria query with Sub-Select AND Left-Outer join? For example, I have A 1-many B 1-many C. With Criteria.createAlias ("b", "b", Criteria.LEFT_JOIN) I can perform Left Outer join. With Criteria.setFetchMode ("b", org.hibernate.FetchMode.DEFAULT) I can perform Join with the default fetching strategy. I assume that having set @org.hibernate.annotations.FetchMode.SUBSELECT in both A.B and B.C is enough (is it?). Question 1: Why does org.hibernate.FetchMode not have SUBSELECT option, whereas the org.hibernate.annotations.FetchMode does? Question 2: Can I perform a Criteria query with Sub-Select AND Left-Outer join?

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  • Cascading updates with business key equality: Hibernate best practices?

    - by Traphicone
    I'm new to Hibernate, and while there are literally tons of examples to look at, there seems to be so much flexibility here that it's sometimes very hard to narrow all the options down the best way of doing things. I've been working on a project for a little while now, and despite reading through a lot of books, articles, and forums, I'm still left with a bit of a head scratcher. Any veteran advice would be very appreciated. So, I have a model involving two classes with a one-to-many relationship from parent to child. Each class has a surrogate primary key and a uniquely constrained composite business key. <class name="Container"> <id name="id" type="java.lang.Long"> <generator class="identity"/> </id> <properties name="containerBusinessKey" unique="true" update="false"> <property name="name" not-null="true"/> <property name="owner" not-null="true"/> </properties> <set name="items" inverse="true" cascade="all-delete-orphan"> <key column="container" not-null="true"/> <one-to-many class="Item"/> </set> </class> <class name="Item"> <id name="id" type="java.lang.Long"> <generator class="identity"/> </id> <properties name="itemBusinessKey" unique="true" update="false"> <property name="type" not-null="true"/> <property name="color" not-null="true"/> </properties> <many-to-one name="container" not-null="true" update="false" class="Container"/> </class> The beans behind these mappings are as boring as you can possibly imagine--nothing fancy going on. With that in mind, consider the following code: Container c = new Container("Things", "Me"); c.addItem(new Item("String", "Blue")); c.addItem(new Item("Wax", "Red")); Transaction t = session.beginTransaction(); session.saveOrUpdate(c); t.commit(); Everything works fine the first time, and both the Container and its Items are persisted. If the above code block is executed again, however, Hibernate throws a ConstraintViolationException--duplicate values for the "name" and "owner" columns. Because the new Container instance has a null identifier, Hibernate assumes it is an unsaved transient instance. This is expected but not desired. Since the persistent and transient Container objects have the same business key values, what we really want is to issue an update. It is easy enough to convince Hibernate that our new Container instance is the same as our old one. With a quick query we can get the identifier of the Container we'd like to update, and set our transient object's identifier to match. Container c = new Container("Things", "Me"); c.addItem(new Item("String", "Blue")); c.addItem(new Item("Wax", "Red")); Query query = session.createSQLQuery("SELECT id FROM Container" + "WHERE name = ? AND owner = ?"); query.setString(0, c.getName()); query.setString(1, c.getOwner()); BigInteger id = (BigInteger)query.uniqueResult(); if (id != null) { c.setId(id.longValue()); } Transaction t = session.beginTransaction(); session.saveOrUpdate(c); t.commit(); This almost satisfies Hibernate, but because the one-to-many relationship from Container to Item cascades, the same ConstraintViolationException is also thrown for the child Item objects. My question is: what is the best practice in this situation? It is highly recommended to use surrogate primary keys, and it is also recommended to use business key equality. When you put these two recommendations in to practice together, however, two of the greatest conveniences of Hibernate--saveOrUpdate and cascading operations--seem to be rendered almost completely useless. As I see it, I have only two options: Manually fetch and set the identifier for each object in the mapping. This clearly works, but for even a moderately sized schema this is a lot of extra work which it seems Hibernate could easily be doing. Write a custom interceptor to fetch and set object identifiers on each operation. This looks cleaner than the first option but is rather heavy-handed, and it seems wrong to me that you should be expected to write a plug-in which overrides Hibernate's default behavior for a mapping which follows the recommended design. Is there a better way? Am I making completely the wrong assumptions? I'm hoping that I'm just missing something. Thanks.

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  • Why does Hibernate ignore the JPA2 standardized properties in my persistence.xml?

    - by Ophidian
    I have an extremely simple web application running in Tomcat using Spring 3.0.1, Hibernate 3.5.1, JPA 2, and Derby. I am defining all of my database connectivity in persistence.xml and merely using Spring for dependency injection. I am using embedded Derby as my database. Everything works correctly when I define the driver and url properties in persistence.xml in the classic Hibernate manner as thus: <property name="hibernate.connection.driver_class" value="org.apache.derby.jdbc.EmbeddedDriver"/> <property name="hibernate.connection.url" value="jdbc:derby:webdb;create=true"/> The problems occur when I switch my configuration to the JPA2 standardized properties as thus: <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver"/> <property name="javax.persistence.jdbc.url" value="jdbc:derby:webdb;create=true"/> When using the JPA2 property keys, the application bails hard with the following exception: java.lang.UnsupportedOperationException: The user must supply a JDBC connection Does anyone know why this is failing? NOTE: I have copied the javax... property strings straight from the Hibernate reference documentation, so a typo is extremely unlikely.

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  • What are the hibernate annotations used to persist a value typed Map with an enumerated type as a ke

    - by Jason Novak
    I am having trouble getting the right hibernate annotations to use on a value typed Map with an enumerated class as a key. Here is a simplified (and extremely contrived) example. public class Thing { public String id; public Letter startLetter; public Map<Letter,Double> letterCounts = new HashMap<Letter, Double>(); } public enum Letter { A, B, C, D } Here are my current annotations on Thing @Entity public class Thing { @Id public String id; @Enumerated(EnumType.STRING) public Letter startLetter; @CollectionOfElements @JoinTable(name = "Thing_letterFrequencies", joinColumns = @JoinColumn(name = "thingId")) @MapKey(columns = @Column(name = "letter", nullable = false)) @Column(name = "count") public Map<Letter,Double> letterCounts = new HashMap<Letter, Double>(); } Hibernate generates the following DDL to create the tables for my MySql database create table Thing (id varchar(255) not null, startLetter varchar(255), primary key (id)) type=InnoDB; create table Thing_letterFrequencies (thingId varchar(255) not null, count double precision, letter tinyblob not null, primary key (thingId, letter)) type=InnoDB; Notice that hibernate tries to define letter (my map key) as a tinyblob, however it defines startLetter as a varchar(255) even though both are of the enumerated type Letter. When I try to create the tables I see the following error BLOB/TEXT column 'letter' used in key specification without a key length I googled this error and it appears that MySql has issues when you try to make a tinyblob column part of a primary key, which is what hibernate needs to do with the Thing_letterFrequencies table. So I would rather have letter mapped to a varchar(255) the way startLetter is. Unfortunately, I've been fussing with the MapKey annotation for a while now and haven't been able to make this work. I've also tried @MapKeyManyToMany(targetEntity=Product.class) without success. Can anyone tell me what are the correct annotations for my letterCounts map so that hibernate will treat the letterCounts map key the same way it does startLetter?

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  • How to use Hibernate SchemaUpdate class with a JPA persistence.xml?

    - by John Rizzo
    I've a main method using SchemaUpdate to display at the console what tables to alter/create and it works fine in my Hibernate project: public static void main(String[] args) throws IOException { //first we prepare the configuration Properties hibProps = new Properties(); hibProps.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("jbbconfigs.properties")); Configuration cfg = new AnnotationConfiguration(); cfg.configure("/hibernate.cfg.xml").addProperties(hibProps); //We create the SchemaUpdate thanks to the configs SchemaUpdate schemaUpdate = new SchemaUpdate(cfg); //The update is executed in script mode only schemaUpdate.execute(true, false); ... I'd like to reuse this code in a JPA project, having no hibernate.cfg.xml file (and no .properties file), but a persistence.xml file (autodetected in the META-INF directory as specified by the JPA spec). I tried this too simple adaptation, Configuration cfg = new AnnotationConfiguration(); cfg.configure(); but it failed with that exception. Exception in thread "main" org.hibernate.HibernateException: /hibernate.cfg.xml not found Has anybody done that? Thanks.

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  • Does Hibernate support one-to-one associations as pkeys?

    - by Andrzej Doyle
    Hi all, Can anyone tell me whether Hibernate supports associations as the pkey of an entity? I thought that this would be supported but I am having a lot of trouble getting any kind of mapping that represents this to work. In particular, with the straight mapping below: @Entity public class EntityBar { @Id @OneToOne(optional = false, mappedBy = "bar") EntityFoo foo // other stuff } I get an org.hibernate.MappingException: "Could not determine type for: EntityFoo, at table: ENTITY_BAR, for columns: [org.hibernate.mapping.Column(foo)]" Diving into the code it seems the ID is always considered a Value type; i.e. "anything that is persisted by value, instead of by reference. It is essentially a Hibernate Type, together with zero or more columns." I could make my EntityFoo a value type by declaring it serializable, but I wouldn't expect this would lead to the right outcome either. I would have thought that Hibernate would consider the type of the column to be integer (or whatever the actual type of the parent's ID is), just like it would with a normal one-to-one link, but this doesn't appear to kick in when I also declare it an ID. Am I going beyond what is possible by trying to combine @OneToOne with @Id? And if so, how could one model this relationship sensibly?

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