This page describes functionality provided by the Tapestry-hibernate-core module, but the descriptions apply equally to the Tapestry-jpa module.{
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Entity value encoding
The Tapestry-hibernate-core module provides Value Encoder automatically for all mapped Hibernate entity types. This is done by encoding the entity as it's id (coerced to a String) and decoding the entity by looking it up in the Hibernate Session using the encoded id. Consider the following example:
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Accessing the page as /viewperson/152 would load the Person entity with id 152 and use that as the page context.
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If you prefer to use annotations, you may let Tapestry generate the page activation context handlers for you. Relying on an existing ValueEncoder for the corresponding property you can use the @PageActivationContext annotation. The disadvantage is that you can't access the handlers in a unit test.
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Using @Persist with entities
If you wish to persist an entity in the session, you may use the "entity" persistence strategy:
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This persistence strategy works with any Hibernate entity that is associated with a valid Hibernate Session by persisting only the id of the entity. Notice that no onPassivate() method is needed; when the page renders the entity is loaded by the id stored in the session.
Using @SessionState with entities
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The default strategy for persisting Session State Objects is "session". Storing a Hibernate entity into a <HttpSession> is problematic because the stored entity is detached from the Hibernate session. Similar to @Persist("entity") you may use the "entity" persistence strategy to persist Hibernate entities as SSOs:
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For this purpose you need to set the value of the symbol <HibernateSymbols.ENTITY_SESSION_STATE_PERSISTENCE_STRATEGY_ENABLED> to <true>:
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Alternatively you can apply the "entity" persistence strategy to a single Hibernate entity:
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Committing Changes
All Hibernate operations occur in a transaction, but that transaction is aborted at the end of each request; thus any changes you make will be lost unless the transaction is committed.
The correct way to commit the transaction is via the @CommitAfter annotation:
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In this example, the Person object may be updated by a form; the form's success event handler method, onSuccess() has the @CommitAfter annotation.
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First definine your DAO's service interface:
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Next, define your service in your application's Module class:
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Finally, you should use the HibernateTransactionAdvisor to add transaction advice:
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This advice method is configured to match against any service whose id ends with "DAO", such as "PersonDAO".
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