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Flash5/flash-extensions/flash-ext-data-hibernate/docs/README.md
T
Zakaria El OrcheandClaude Opus 5 c5179146c0 docs(data): write the data-layer docs in English
The three data modules' docs were in Italian, so the synchronization contract
added in the previous commit went in as Italian too, to match its file. English
is the project's language for docs, comments and READMEs alike, and a file half
in each is worse than either — so all three are translated, not just the new
section.

Content is otherwise unchanged, except the "synchronizations run on
commit/rollback" line in the two backend READMEs, which was vague before and is
now accurate about which hook sees the session/connection still bound, pointing
at flash-ext-data-core's README for the full contract.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-12 23:36:11 +00:00

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2.9 KiB
Markdown

# flash-ext-data-hibernate
Hibernate backend for `flash-ext-data-core`.
## Purpose
This module implements `TxManager` on top of a `SessionFactory` and provides a Hibernate-centric
repository base class.
## How to use it
### 1. Create the manager
```java
SessionFactory sessionFactory = ...;
HibernateTxManager txManager = new HibernateTxManager(sessionFactory);
DataExtension extension = new DataExtension(txManager);
```
### 2. Install the extension in Flash
The extension registers `Tx` and `TxManager` in the `FlashContext`. Class-based handlers annotated
with `@Transactional` are wrapped automatically.
### 3. Define a repository
```java
public final class UserRepository extends HibernateRepository<User, Long> {
public UserRepository(Tx tx) {
super(tx, User.class);
}
}
```
With the query/spec model you can expose reusable fields as constants:
```java
public final class UserRepository extends HibernateRepository<User, Long> {
public static final SpecBuilder.FieldSpec<User, String> EMAIL = SpecBuilder.field("u.email");
public static final SpecBuilder.FieldSpec<User, Boolean> ACTIVE = SpecBuilder.field("u.active");
public UserRepository(Tx tx) {
super(tx, User.class);
}
public Optional<User> findByEmail(String email) {
return findOne(EMAIL.eq(email));
}
}
```
Domain-specific queries can use the base class helpers:
```java
public List<User> findByEmailDomain(String domain) {
return findMany("from User u where u.email like :email", q ->
q.setParameter("email", "%@" + domain)
);
}
```
## How it works underneath
- The current transaction is represented by `HibernateTxStatus`.
- The resource exposed to the core is a `Session`.
- `Tx.resource(Session.class)` retrieves the `Session` from the current context.
- `REQUIRES_NEW` suspends the active status and opens a new `Session`.
- `NOT_SUPPORTED` suspends the active transaction and continues with no session bound.
## Repository base class
`HibernateRepository` provides:
- `findById`, `findAll`, `findPage`, `findOne`
- `save`, `update`, `delete`, `saveAll`
- bulk `deleteAll(Spec<T>)` and `updateAll(Spec<T>, T)`
- HQL helpers: `hql(...)`, `hqlMutate(...)`
Concrete classes only have to implement domain queries, never the transactional plumbing.
## Transactional semantics
- `REQUIRED`: join, or open a new transaction.
- `REQUIRES_NEW`: suspend the current context.
- `SUPPORTS`: join if a transaction exists, otherwise no-op.
- `NOT_SUPPORTED`: suspend and continue without a transaction.
- `MANDATORY`: fail if there is no transaction.
## Notes
- The `Session` is closed when a new transaction ends.
- Synchronizations registered in a transaction fire when *that* transaction completes:
`beforeCommit` while it is still active and the `Session` still bound, the post-completion hooks
once it is unbound. See `flash-ext-data-core/docs/README.md` for the full contract.
- This backend is meant to be used through the base class, not directly.