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Hibernate ORM
Domain model persistence for relational databases

Hibernate Search
Full-text search for your domain model

Hibernate Validator
Annotation based constraints for your domain model

Hibernate OGM
Domain model persistence for NoSQL datastores

Hibernate Tools
Command line tools and IDE plugins for your Hibernate usages

Others
We like the symmetry, everything else is here

Here are some Hibernate Annotations related FAQs.
Hibernate Annotations FAQ
I have migrated to a newer version and something went wrong
I can't EAGER more than one collection !?
I get an exception when I load more than one collection !?
I use @org.hibernate.annotations.Entity and get an Unknown entity exception
I have AnnotationException: No identifier specified for entity
I'm having NoSuchMethodException(s)
How to make the reverse engineering tools create an appropriate annotated composite id?
Where can I see the hbm.xml files generated from the Annotations?
I have issues with the schema creation with Derby
@Serialized was working for me, and now that I use @Lob it fails
How can I set inverse="true"?
How do I persist my superclass properties?
My Annotated class will not load

Hibernate définit et prend en charge les états d'objets suivants :

Éphémère (transient) - un objet est éphémère s'il a juste été instancié en utilisant l'opérateur new. Il n'a aucune représentation persistante dans la base de données et aucune valeur d'identifiant n'a été assignée. Les instances éphémères seront détruites par le ramasse-miettes si l'application n'en conserve aucune référence. Utilisez la Session d'Hibernate pour rendre un objet persistant (et laisser Hibernate s'occuper des expressions SQL qui ont besoin d'être exécutées pour cette transistion).
Persistant - une instance persistante a une représentation dans la base de données et une valeur d'identifiant. Elle pourrait avoir juste été sauvegardée ou chargée, pourtant, elle est par définition dans la portée d'une Session. Hibernate détectera tout changement effectué sur un objet dans l'état persistant et synchronisera l'état avec la base de données lors de la fin de l'unité de travail. Les développeurs n'exécutent pas d'expressions UPDATE ou DELETE manuelles lorsqu'un objet devrait être rendu éphémère.
Détaché - une instance détachée est un objet qui a été persistant, mais dont la Session a été fermée. La référence à l'objet est encore valide, bien sûr, et l'instance détachée pourrait même être modifiée dans cet état. Une instance détachée peut être rattachée à une nouvelle Session ultérieurement, la rendant (et toutes les modifications avec) de nouveau persistante. Cette fonctionnalité rend possible un modèle de programmation pour de longues unités de travail qui requièrent un temps de réflexion de l'utilisateur. Nous les appelons des conversations, c'est-à-dire une unité de travail du point de vue de l'utilisateur.

Enable full-text search capabilities on your Entities
To achieve this you have to add a few annotations

Last week I was implementing a new report using MySQL, and some of the data was stored in JSON format. MySQL has lots of built-in string functions, but none of them work for JSON. My first idea was to use the mysql_json UDF, but then I remembered that common_schema recently added JSON parsing. Since I have common_schema 1.3 installed on all of my databases already, I tried that first.

This FAQ covers basic issues you can get when using Hibernate. For more advanced topics, see XXXXX
 
Common problems
I get a ClassNotFoundException or NoClassDefFoundError
I get a ObjectNotFoundException: No row with the given identifier exists
I get InvalidObjectException: Could not find a SessionFactory named: null
I get org.hibernate.HibernateException: CGLIB Enhancement failed: ?
I saved / deleted / updated an object / collection but I can't see the changes in the database!
I saved a parent object but its associated objects weren't saved to the database.
I called saveOrUpdate() or update() and got a NonUniqueObjectException!
I'm using a one-to-many association with a NOT NULL constraint on the key column and Hibernate causes constraint violations.
I'm having trouble with a bidirectional association.
Can't I have a bidirectional association using a List or Map?
I get a log message: Parsing XML: unknown system id
I get a log message: reflection optimizer disabled
Hibernate keeps deleting and recreating my collection!
Hibernate throws a PropertyAccessException or NullPointerException when I load or query an object!
I removed an object from a collection mapped with cascade="all" but the object was not deleted!
Hibernate updates an object in the database, when I didn't change anything!
How can I get Hibernate to persist an instance variable that does not have property accessors, or simply bypass the property accessors?
Hibernate is nontransparent because it requires me to have a default constructor which breaks the API of my class!
I'm confused about the semantics of saveOrUpdate().
I don't know if I should use save() or persist().
How does inverse="true" affect the semantics of cascade="all"?
I get a ClassCastException when using a composite identifier
I get a ClassCastException when I specify a collection sort attribute.
I have some other kind of wierd bugs.....
Does Hibernate support database views?
I'm using Hibernate in a CMT session bean or BMP entity bean and I recieve an exception whenever I try to commit() the Transaction or JDBC Connection.
How do I use Hibernate with CMT?
How do a write a query that returns objects based upon a WHERE clause condition applied to their collection elements?
I want to retrieve query results, one page at a time
I see a java.lang.AbstractMethodError: net/sf/hibernate/persister/AbstractEntityPersister.... at startup!
I am getting a PropertyAccessException, and the error trace suggests to turn off the reflection optimizer. Howerver, it doesn't seem that I can set this in hibernate.cfg.xml.
Hibernate tries to connect to http://hibernate.sourceforge.net at startup!
I've enabled the second-level cache and my queries are not being cached!
Hibernate returns java.sql.Date instead of java.util.Date!
What is the lifecycle of a Hibernate Session?
I'm having trouble configuring association fetching strategies...

Advanced Problems Here are the solutions to some frequent advanced problems. 

Table of Contents

Preface
1. Tutorial
1.1. Part 1 - The first Hibernate Application
1.1.1. Setup
1.1.2. The first class
1.1.3. The mapping file
1.1.4. Hibernate configuration
1.1.5. Building with Maven
1.1.6. Startup and helpers
1.1.7. Loading and storing objects
1.2. Part 2 - Mapping associations
1.2.1. Mapping the Person class
1.2.2. A unidirectional Set-based association
1.2.3. Working the association
1.2.4. Collection of values
1.2.5. Bi-directional associations
1.2.6. Working bi-directional links
1.3. Part 3 - The EventManager web application
1.3.1. Writing the basic servlet
1.3.2. Processing and rendering
1.3.3. Deploying and testing
1.4. Summary
2. Architecture
2.1. Overview
2.1.1. Minimal architecture
2.1.2. Comprehensive architecture
2.1.3. Basic APIs
2.2. Contextual sessions
3. Configuration
3.1. Programmatic configuration
3.2. Obtaining a SessionFactory
3.3. JDBC connections
3.4. Optional configuration properties
3.4.1. SQL Dialects
3.4.2. Outer Join Fetching
3.4.3. Binary Streams
3.4.4. Second-level and query cache
3.4.5. Query Language Substitution
3.4.6. Hibernate statistics
3.5. Logging
3.6. Implementing a NamingStrategy
3.7. Implementing a PersisterClassProvider
3.8. XML configuration file
3.9. Java EE Application Server integration
3.9.1. Transaction strategy configuration
3.9.2. JNDI-bound SessionFactory
3.9.3. Current Session context management with JTA
4. Persistent Classes
4.1. A simple POJO example
4.1.1. Implement a no-argument constructor
4.1.2. Provide an identifier property
4.1.3. Prefer non-final classes (semi-optional)
4.1.4. Declare accessors and mutators for persistent fields (optional)
4.2. Implementing inheritance
4.3. Implementing equals() and hashCode()
4.4. Dynamic models
4.5. Tuplizers
4.6. EntityNameResolvers
5. Basic O/R Mapping
5.1. Mapping declaration
5.1.1. Entity
5.1.2. Identifiers
5.1.3. Optimistic locking properties (optional)
5.1.4. Property
5.1.5. Embedded objects (aka components)
5.1.6. Inheritance strategy
5.1.7. Mapping one to one and one to many associations
5.1.8. Natural-id
5.1.9. Any
5.1.10. Properties
5.1.11. Some hbm.xml specificities
5.2. Hibernate types
5.2.1. Entities and values
5.2.2. Basic value types
5.2.3. Custom value types
5.3. Mapping a class more than once
5.4. SQL quoted identifiers
5.5. Generated properties
5.6. Column transformers: read and write expressions
5.7. Auxiliary database objects
6. Types
6.1. Value types
6.1.1. Basic value types
6.1.2. Composite types
6.1.3. Collection types
6.2. Entity types
6.3. Significance of type categories
6.4. Custom types
6.4.1. Custom types using org.hibernate.type.Type
6.4.2. Custom types using org.hibernate.usertype.UserType
6.4.3. Custom types using org.hibernate.usertype.CompositeUserType
6.5. Type registry
7. Collection mapping
7.1. Persistent collections
7.2. How to map collections
7.2.1. Collection foreign keys
7.2.2. Indexed collections
7.2.3. Collections of basic types and embeddable objects
7.3. Advanced collection mappings
7.3.1. Sorted collections
7.3.2. Bidirectional associations
7.3.3. Bidirectional associations with indexed collections
7.3.4. Ternary associations
7.3.5. Using an
7.4. Collection examples
8. Association Mappings
8.1. Introduction
8.2. Unidirectional associations
8.2.1. Many-to-one
8.2.2. One-to-one
8.2.3. One-to-many
8.3. Unidirectional associations with join tables
8.3.1. One-to-many
8.3.2. Many-to-one
8.3.3. One-to-one
8.3.4. Many-to-many
8.4. Bidirectional associations
8.4.1. one-to-many / many-to-one
8.4.2. One-to-one
8.5. Bidirectional associations with join tables
8.5.1. one-to-many / many-to-one
8.5.2. one to one
8.5.3. Many-to-many
8.6. More complex association mappings
9. Component Mapping
9.1. Dependent objects
9.2. Collections of dependent objects
9.3. Components as Map indices
9.4. Components as composite identifiers
9.5. Dynamic components
10. Inheritance mapping
10.1. The three strategies
10.1.1. Table per class hierarchy
10.1.2. Table per subclass
10.1.3. Table per subclass: using a discriminator
10.1.4. Mixing table per class hierarchy with table per subclass
10.1.5. Table per concrete class
10.1.6. Table per concrete class using implicit polymorphism
10.1.7. Mixing implicit polymorphism with other inheritance mappings
10.2. Limitations
11. Working with objects
11.1. Hibernate object states
11.2. Making objects persistent
11.3. Loading an object
11.4. Querying
11.4.1. Executing queries
11.4.2. Filtering collections
11.4.3. Criteria queries
11.4.4. Queries in native SQL
11.5. Modifying persistent objects
11.6. Modifying detached objects
11.7. Automatic state detection
11.8. Deleting persistent objects
11.9. Replicating object between two different datastores
11.10. Flushing the Session
11.11. Transitive persistence
11.12. Using metadata
12. Read-only entities
12.1. Making persistent entities read-only
12.1.1. Entities of immutable classes
12.1.2. Loading persistent entities as read-only
12.1.3. Loading read-only entities from an HQL query/criteria
12.1.4. Making a persistent entity read-only
12.2. Read-only affect on property type
12.2.1. Simple properties
12.2.2. Unidirectional associations
12.2.3. Bidirectional associations
13. Transactions and Concurrency
13.1. Session and transaction scopes
13.1.1. Unit of work
13.1.2. Long conversations
13.1.3. Considering object identity
13.1.4. Common issues
13.2. Database transaction demarcation
13.2.1. Non-managed environment
13.2.2. Using JTA
13.2.3. Exception handling
13.2.4. Transaction timeout
13.3. Optimistic concurrency control
13.3.1. Application version checking
13.3.2. Extended session and automatic versioning
13.3.3. Detached objects and automatic versioning
13.3.4. Customizing automatic versioning
13.4. Pessimistic locking
13.5. Connection release modes
14. Interceptors and events
14.1. Interceptors
14.2. Event system
14.3. Hibernate declarative security
15. Batch processing
15.1. Batch inserts
15.2. Batch updates
15.3. The StatelessSession interface
15.4. DML-style operations
16. HQL: The Hibernate Query Language
16.1. Case Sensitivity
16.2. The from clause
16.3. Associations and joins
16.4. Forms of join syntax
16.5. Referring to identifier property
16.6. The select clause
16.7. Aggregate functions
16.8. Polymorphic queries
16.9. The where clause
16.10. Expressions
16.11. The order by clause
16.12. The group by clause
16.13. Subqueries
16.14. HQL examples
16.15. Bulk update and delete
16.16. Tips & Tricks
16.17. Components
16.18. Row value constructor syntax
17. Criteria Queries
17.1. Creating a Criteria instance
17.2. Narrowing the result set
17.3. Ordering the results
17.4. Associations
17.5. Dynamic association fetching
17.6. Components
17.7. Collections
17.8. Example queries
17.9. Projections, aggregation and grouping
17.10. Detached queries and subqueries
17.11. Queries by natural identifier
18. Native SQL
18.1. Using a SQLQuery
18.1.1. Scalar queries
18.1.2. Entity queries
18.1.3. Handling associations and collections
18.1.4. Returning multiple entities
18.1.5. Returning non-managed entities
18.1.6. Handling inheritance
18.1.7. Parameters
18.2. Named SQL queries
18.2.1. Using return-property to explicitly specify column/alias names
18.2.2. Using stored procedures for querying
18.3. Custom SQL for create, update and delete
18.4. Custom SQL for loading
19. Filtering data
19.1. Hibernate filters
20. Improving performance
20.1. Fetching strategies
20.1.1. Working with lazy associations
20.1.2. Tuning fetch strategies
20.1.3. Single-ended association proxies
20.1.4. Initializing collections and proxies
20.1.5. Using batch fetching
20.1.6. Using subselect fetching
20.1.7. Fetch profiles
20.1.8. Using lazy property fetching
20.2. The Second Level Cache
20.2.1. Cache mappings
20.2.2. Strategy: read only
20.2.3. Strategy: read/write
20.2.4. Strategy: nonstrict read/write
20.2.5. Strategy: transactional
20.2.6. Cache-provider/concurrency-strategy compatibility
20.3. Managing the caches
20.4. The Query Cache
20.4.1. Enabling query caching
20.4.2. Query cache regions
20.5. Bytecode Enhancement
20.5.1. Implementing org.hibernate.engine.spi.ManagedEntity interface
20.5.2. Runtime instrument
20.5.3. Build-time instrument
20.6. Understanding Collection performance
20.6.1. Taxonomy
20.6.2. Lists, maps, idbags and sets are the most efficient collections to update
20.6.3. Bags and lists are the most efficient inverse collections
20.6.4. One shot delete
20.7. Monitoring performance
20.7.1. Monitoring a SessionFactory
20.7.2. Metrics
21. Toolset Guide
21.1. Automatic schema generation
21.1.1. Customizing the schema
21.1.2. Running the tool
21.1.3. Properties
21.1.4. Using Ant
21.1.5. Incremental schema updates
21.1.6. Using Ant for incremental schema updates
21.1.7. Schema validation
21.1.8. Using Ant for schema validation
22. Additional modules
22.1. Bean Validation
22.1.1. Adding Bean Validation
22.1.2. Configuration
22.1.3. Catching violations
22.1.4. Database schema
22.2. Hibernate Search
22.2.1. Description
22.2.2. Integration with Hibernate Annotations
23. Example: Parent/Child
23.1. A note about collections
23.2. Bidirectional one-to-many
23.3. Cascading life cycle
23.4. Cascades and unsaved-value
23.5. Conclusion
24. Example: Weblog Application
24.1. Persistent Classes
24.2. Hibernate Mappings
24.3. Hibernate Code
25. Example: Various Mappings
25.1. Employer/Employee
25.2. Author/Work
25.3. Customer/Order/Product
25.4. Miscellaneous example mappings
25.4.1. "Typed" one-to-one association
25.4.2. Composite key example
25.4.3. Many-to-many with shared composite key attribute
25.4.4. Content based discrimination
25.4.5. Associations on alternate keys
26. Best Practices
27. Database Portability Considerations
27.1. Portability Basics
27.2. Dialect
27.3. Dialect resolution
27.4. Identifier generation
27.5. Database functions
27.6. Type mappings
References

20.34.MySQL
20.34.1. Get a MySQL Connection from the Driver Manager
20.34.2. JDBC Mysql Connection String
20.34.3. MySQL Connection Properties: Passing Additional Properties Using a Database URL
20.34.4. Keep the Connection Alive for MySQL
20.34.5. MySQL Data type to Java Data type Conversion Table
20.34.6. Create a MySQL Table to Store Java Types (Using Statement Objects)?
20.34.7. Retrieve Automatically Generated Keys Using a Statement (MySQL)?
20.34.8. Creating a MySQL Table to Store Java Types
20.34.9. Loading a Flat File to a MySQL Table, file is comma-separated