EntityAssist Reactive Skill

EntityAssist Reactive

CRTP-first reactive persistence toolkit for GuicedEE services with Hibernate Reactive 7 and Mutiny.

Core Features

CRTP-shaped entities — BaseEntity<J, Q, I> with self-referencing fluent setters
Fluent query builder DSL — Composable where(), or(), orderBy(), groupBy(), join()
Reactive CRUD with Mutiny — All operations return Uni<T>
Dot-notation path filters — where("roles.name", Equals, "ADMIN")
Pagination — setFirstResults() / setMaxResults()
Aggregate projections — selectMin(), selectMax(), selectSum(), selectAverage(), selectCount()
Join support — INNER, LEFT, RIGHT joins with on-clause builders
Common Table Expressions — Fluent with() / withRecursiveHierarchy() CTEs (Hibernate 7)
Bulk operations — Criteria delete and update with safety guards
Stateless sessions — High-throughput bulk operations
Bean Validation — validateEntity() returns constraint violations

Quick Start

Define a CRTP Entity

@Entity
@Accessors(chain = true)
@Table(name = "entity_class")
public class EntityClass
        extends BaseEntity<EntityClass, EntityClass.EntityClassQueryBuilder, String> {

    @Id
    @Column(name = "id", nullable = false)
    @Getter @Setter
    private String id;

    @Column(name = "name")
    @Getter @Setter
    private String name;

    @Override
    public String getId() { return id; }

    @Override
    public EntityClass setId(String id) {
        this.id = id;
        return this;
    }

    public static class EntityClassQueryBuilder
            extends QueryBuilder<EntityClassQueryBuilder, EntityClass, String> {

        @Override
        public boolean isIdGenerated() {
            return false;
        }
    }
}

Entity with Relationships

@Entity
@Accessors(chain = true)
@Table(name = "entity_class_two")
public class EntityClassTwo
        extends BaseEntity<EntityClassTwo, EntityClassTwo.EntityClassTwoQueryBuilder, String> {

    @Id
    @Getter @Setter
    private String id;

    @Column(name = "value")
    @Getter @Setter
    private Integer value;

    @ManyToOne
    @JoinColumn(name = "entity_class_id")
    @Getter @Setter
    private EntityClass entityClass;

    @Override
    public String getId() { return id; }

    @Override
    public EntityClassTwo setId(String id) {
        this.id = id;
        return this;
    }

    public static class EntityClassTwoQueryBuilder
            extends QueryBuilder<EntityClassTwoQueryBuilder, EntityClassTwo, String> {

        @Override
        public boolean isIdGenerated() {
            return false;
        }
    }
}

Type Hierarchy

IRootEntity                      IQueryBuilderRoot
  └─ IDefaultEntity                └─ IDefaultQueryBuilder
      └─ IBaseEntity                   └─ IQueryBuilder
          ↑                                ↑
 RootEntity<J,Q,I>              QueryBuilderRoot<J,E,I>
   └─ DefaultEntity<J,Q,I>       └─ DefaultQueryBuilder<J,E,I>
       └─ BaseEntity<J,Q,I>          └─ QueryBuilder<J,E,I>
           ↑                              ↑
    Your Entity                    Your QueryBuilder

Every entity binds to its query builder via CRTP generics.

Query Builder DSL

Persist (Create)

sessionFactory.withSession(session ->
    session.withTransaction(tx ->
        entity.builder(session)
              .persist(entity)
    )
).replaceWithVoid();

Find by ID

sessionFactory.withSession(session ->
    new EntityClass()
        .builder(session)
        .find("test1")
        .get()                       // Uni<EntityClass>
);

Where / Or / OrderBy

sessionFactory.withSession(session -> {
    var qb = new EntityClass().builder(session);
    return qb
        .where(qb.getAttribute("name"), Operand.Like, "A%")
        .or(qb.getAttribute("name"), Operand.Equals, "Bob")
        .orderBy(qb.getAttribute("name"), OrderByType.ASC)
        .setMaxResults(50)
        .getAll();                   // Uni<List<EntityClass>>
});

Dot-Notation Path Filters

Traverse relationships without explicit joins:

sessionFactory.withSession(session -> {
    var qb = new EntityClassTwo().builder(session);
    return qb
        .where("entityClass.name", Operand.Equals, "Parent Entity")
        .where("value", Operand.GreaterThan, 10)
        .getAll();
});

where(String path, ...) splits the path on . and walks path.get(segment) for each segment (WhereExpression.buildPath), creating the implicit joins. The filter is applied entirely inside the single criteria query.

Reactive gotcha — filter on a joined column instead of resolving the related entity. In a reactive (Hibernate Reactive / Mutiny) codebase you must never resolve a related entity synchronously just to use it in a where(...). Calling another find(...) returns a Uni, and casting that Uni to the entity type throws ClassCastException at runtime (UniOnItemTransformToUni cannot be cast to <Entity>); awaiting/blocking it on the event loop is equally forbidden. Filter on the join path instead:
// ❌ BAD — blocks/casts a Uni to an entity to use it in where(...)
ClassificationDataConcept dc = (ClassificationDataConcept) service.find(em, concept, system); // Uni!
builder.where(Classification_.concept, Operand.Equals, dc);

// ✅ GOOD — fully non-blocking: filter on the joined column directly
builder.where("concept.name", Operand.Equals, concept.classificationValue());
When the join key has a stable natural value (here the concept's persisted name equals EnterpriseClassificationDataConcepts.classificationValue()), the dot-notation filter is exactly equivalent to the entity-equality filter and stays on the reactive pipeline. This pattern fixed a real ClassCastException in ClassificationQueryBuilder.withConcept.

Pagination

sessionFactory.withSession(session -> {
    var qb = new EntityClass().builder(session);
    return qb
        .where(qb.getAttribute("name"), Operand.Like, "A%")
        .orderBy(qb.getAttribute("name"), OrderByType.ASC)
        .setFirstResults(0)
        .setMaxResults(20)
        .getAll();
});

Count

sessionFactory.withSession(session -> {
    var qb = new EntityClass().builder(session);
    return qb
        .where(qb.getAttribute("name"), Operand.Like, "A%")
        .getCount();                 // Uni<Long>
});

Aggregate Projections

sessionFactory.withSession(session -> {
    var qb = new EntityClassTwo().builder(session);
    return qb
        .selectMax(qb.getAttribute("value"))
        .get(Integer.class);         // Uni<Integer>
});

Available aggregates:

selectMin()
selectMax()
selectSum()
selectSumAsDouble()
selectSumAsLong()
selectAverage()
selectCount()
selectCountDistinct()
selectColumn()

Joins

sessionFactory.withSession(session -> {
    var parent = new EntityClass().builder(session);
    var child = new EntityClassTwo().builder(session);
    return child
        .join(child.getAttribute("entityClass"), parent, JoinType.INNER)
        .where(parent.getAttribute("name"), Operand.Equals, "Parent Entity")
        .getAll();
});

Common Table Expressions (CTEs)

CTEs compose in the same fluent builder pattern. A CTE is described by a normal builder (its where(...) filters), registered with with(...), and the outer query is constrained to the CTE's rows via an id IN (SELECT id FROM cte) predicate — so results are real managed entities and the entire DSL (where, orderBy, groupBy, projections, getAll, getCount) keeps working.

Requires Hibernate ORM 7 (the builder uses HibernateCriteriaBuilder / JpaCriteriaQuery under the hood). In this Hibernate version a CTE is materialised as a tuple, so EntityAssist projects the entity @Id into the CTE and filters the outer entity query by membership rather than re-rooting it.

Non-recursive CTE

sessionFactory.withSession(session -> {
    // CTE body — just another builder with its own filters
    var activeOnly = new EntityClass().builder(session)
            .where("description", Operand.Equals, "ACTIVE");

    // Outer entity query constrained by the CTE, then filtered normally
    return new EntityClass().builder(session)
            .with("active_entities", activeOnly)   // WITH active_entities AS (SELECT id ...)
            .where("name", Operand.Like, "A%")
            .getAll();                             // Uni<List<EntityClass>>
});

Generated SQL:

WITH active_entities (active_entities_id) AS (
    SELECT e.id FROM entity_class e WHERE e.description = ?
)
SELECT m.* FROM entity_class m
WHERE m.id IN (SELECT active_entities_id FROM active_entities)
  AND m.name LIKE ?

Recursive CTE (adjacency-list hierarchy)

withRecursiveHierarchy(name, anchor, parentAttribute) walks a self-referencing hierarchy and returns the anchor row plus every descendant. parentAttribute is the self-referencing attribute holding the parent identifier (a scalar FK column; dot-paths such as "parent.id" are supported for associations).

@Entity
@Table(name = "category_node")
public class CategoryNode
        extends BaseEntity<CategoryNode, CategoryNode.CategoryNodeQueryBuilder, String> {
    @Id private String id;
    private String name;
    @Column(name = "parent_id") private String parentId;   // self-reference
    // getters/setters + builder ...
}

sessionFactory.withSession(session -> {
    var anchor = new CategoryNode().builder(session)
            .where("id", Operand.Equals, "1");           // start at node 1

    return new CategoryNode().builder(session)
            .withRecursiveHierarchy("subtree", anchor, "parentId")
            .getAll();                                   // node 1 + all descendants
});

Generated SQL:

WITH RECURSIVE subtree (subtree_id) AS (
    SELECT e.id FROM category_node e WHERE e.id = ?          -- anchor member
    UNION ALL
    SELECT c.id FROM category_node c, subtree                -- recursive member
    WHERE c.parent_id = subtree.subtree_id
)
SELECT m.* FROM category_node m
WHERE m.id IN (SELECT subtree_id FROM subtree)

Low-level recursive CTE

For non-hierarchy recursion, withRecursive(name, anchor, recursiveProducer, unionAll) exposes Hibernate's recursive member directly as Function<JpaCteCriteria<Object>, AbstractQuery<Object>> (the CTE projects the entity id; unionAll = false switches to UNION DISTINCT).

Notes:

Call with(...) / withRecursiveHierarchy(...) once per CTE; multiple CTEs accumulate.
A unique CTE name is generated when name is null/blank.
The CTE body builder must target the same entity type as the outer builder.
The entity must expose a single @Id field.

Recursion over a link / join table (not just self-FK adjacency)

withRecursiveHierarchy(...) only fits an adjacency list on one entity (a self-referencing FK: child.parent_id = tree.id). When the hierarchy is stored in a separate link table — a many-to-many / association entity such as ParentXChild(parentId, childId) — withRecursiveHierarchy cannot express it (its recursive member always re-roots on the same entity). Use the low-level withRecursive(...) instead: its recursiveProducer is raw Hibernate criteria, so the recursive member may root on a different mapped entity (the link table) and project a column back as the outer entity's id.

Requirements / shape:

The outer builder and the anchor builder are rooted on the target entity E (the CTE projects E's @Id, and the outer query is trimmed by id IN (SELECT … FROM cte)).
The link table must be a mapped EntityAssist entity (it needs a query builder / metamodel).
The recursive member selects the link column that yields the next E id (e.g. select x.parentId from ParentXChild x, cte a where x.childId = a.<cteIdAlias> + any edge filters), aliased to the CTE id alias and typed as E's id type.

// Climb a parent/child hierarchy stored in a link table (childId → parentId), seeded from an anchor.
var anchor = new SecurityToken().builder(session)
        .where("securityToken", Operand.InList, tokenStrings)
        .where("enterpriseId", Operand.Equals, enterpriseId);

return new SecurityToken().builder(session)
        .withRecursive("applicable", anchor, cteRef -> {
            var cb        = (HibernateCriteriaBuilder) builder.getCriteriaBuilder();
            var recursive = cb.createQuery(UUID.class);
            var x         = recursive.from(SecurityTokenXSecurityToken.class);  // the LINK entity
            var a         = recursive.from(cteRef);
            var parentId  = x.get("parentSecurityTokenId");
            parentId.alias("applicable_id");
            recursive.select(parentId);
            recursive.where(cb.and(
                    cb.equal(x.get("childSecurityTokenId"), a.get("applicable_id")),
                    /* edge filters: enterprise, SCD in-range, active-flag visible … */));
            return recursive;
        }, /* unionAll */ false)            // UNION DISTINCT dedupes diamond hierarchies
        .getAll();                          // every SecurityToken reachable by climbing parents

Why this matters (CTE fusion). Because the climb constrains a real E builder via id IN (SELECT … FROM cte), it composes with the rest of the DSL in the same statement — so a recursive expansion and a downstream membership/security trim (e.g. an id IN (readableIds) / canRead(...) filter) run as one CTE-backed query instead of: native recursive query → collect a Set<UUID> → second IN (…) query. It is also fully portable (no vendor SQL string) and goes through Hibernate Reactive, which auto-flushes before the query — removing any "pin :now to a logical clock because the native query doesn't flush" visibility workarounds. Trade-off: the recursiveProducer is raw criteria (more verbose than fluent where(...)), so the win is portability + composition/fusion, not fewer lines.

Bulk Delete

sessionFactory.withSession(session ->
    session.withTransaction(tx -> {
        var qb = new EntityClass().builder(session);
        return qb
            .where(qb.getAttribute("name"), Operand.Equals, "obsolete")
            .delete();               // Uni<Integer> — rows affected
    })
);

Safety guard: Bulk delete() requires at least one filter. Use truncate() to remove all rows.

Entity Delete

sessionFactory.withSession(session ->
    session.withTransaction(tx ->
        entity.builder(session)
              .delete(entity)        // Uni<EntityClass>
    )
);

Update (Merge)

entity.setName("Updated Name");
sessionFactory.withSession(session ->
    session.withTransaction(tx ->
        entity.builder(session)
              .update()              // Uni<EntityClass>
    )
);

Stateless Sessions

For high-throughput bulk operations:

sessionFactory.withStatelessSession(session ->
    entity.builder(session)           // uses Mutiny.StatelessSession
          .persist(entity)
);

Bulk-insert pattern (resolve-once + one stateless transaction). When securing/post-processing many just-created rows, do NOT loop a per-row operation that re-resolves shared references and round-trips for every row. Resolve the shared values once on the live session, then write all rows in a single withStatelessTransaction so the persistence context never grows and inserts can be JDBC-batched:

// ❌ BAD — per row: N × (re-resolve shared refs + find + persist) round-trips
for (var row : rows) row.createSecurity(session, ...).await()...;

// ✅ GOOD — resolve shared refs once, batch all inserts in ONE stateless tx
return resolveSharedRefs(session, system)                 // 1 pass on the live session
    .chain(refs -> sessionFactory.withStatelessTransaction(st -> {
        Uni<Long> chain = Uni.createFrom().item(0L);
        for (var row : rows)
            chain = chain.chain(n -> row.persistDerived(st, refs).map(k -> n + k));
        return chain;                                     // pure inserts, no growing context
    }));

For just-created rows skip any per-row existence gate entirely (the caller already knows they are new); only use a count == 0 gate when the pass must be idempotent over a whole table (re-installs).

Transactions with Mutiny

sessionFactory.withSession(session ->
    session.withTransaction(tx ->
        new EntityClass().builder(session)
            .persist(new EntityClass().setId("b1").setName("Bob"))
            .chain(() ->
                new EntityClass().builder(session)
                    .find("b1")
                    .get()
            )
            .invoke(found -> log.info("Created and retrieved: {}", found.getName()))
    )
);

Configuration

Database Module

Create a DatabaseModule subclass annotated with @EntityManager:

@EntityManager(value = "entityAssistReactive", defaultEm = true)
public class EntityAssistReactiveDBModule
        extends DatabaseModule<EntityAssistReactiveDBModule>
        implements IGuiceModule<EntityAssistReactiveDBModule> {

    @Override
    protected String getPersistenceUnitName() {
        return "entityAssistReactive";
    }

    @Override
    protected ConnectionBaseInfo getConnectionBaseInfo(
            PersistenceUnitDescriptor unit, Properties filteredProperties) {
        PostgresConnectionBaseInfo connectionInfo = new PostgresConnectionBaseInfo();
        connectionInfo.setServerName("localhost");
        connectionInfo.setPort("5432");
        connectionInfo.setDatabaseName("mydb");
        connectionInfo.setUsername(System.getenv("DB_USER"));
        connectionInfo.setPassword(System.getenv("DB_PASSWORD"));
        connectionInfo.setDefaultConnection(true);
        connectionInfo.setReactive(true);
        return connectionInfo;
    }

    @Override
    protected String getJndiMapping() {
        return "jdbc:entityAssistReactive";
    }
}

JPMS Registration

module my.app {
    requires com.entityassist;
    requires com.guicedee.persistence;

    opens my.app.entities to org.hibernate.orm.core, com.google.guice, com.entityassist;

    provides com.guicedee.client.services.lifecycle.IGuiceModule
        with my.app.MyDatabaseModule;
}

Environment Variables

| Variable | Purpose | Default | |---|---|---| | DB_HOST | Database hostname | localhost | | DB_PORT | Database port | 5432 | | DB_NAME | Database name | — | | DB_USER | Database username | — | | DB_PASSWORD | Database password | — | | ENVIRONMENT | Runtime environment | dev |

Operands

See references/operands.md for complete list.

Common operands:

Equals, NotEquals
Like, NotLike
LessThan, LessThanEqualTo
GreaterThan, GreaterThanEqualTo
Null, NotNull
InList, NotInList

Key Classes

Entities:

RootEntity<J,Q,I> — Root CRTP entity with builder(), persist(), update()
DefaultEntity<J,Q,I> — Intermediate extension point
BaseEntity<J,Q,I> — Primary superclass for user entities

Query Builders:

QueryBuilderRoot<J,E,I> — Root builder with session management
DefaultQueryBuilder<J,E,I> — Fluent DSL methods
QueryBuilder<J,E,I> — Primary superclass for user builders

Expressions:

WhereExpression — Single where predicate
GroupedExpression — AND/OR predicate grouping
JoinExpression — Join definition
CteExpression — Common Table Expression definition (name, body builder, recursion)
SelectExpression — Column selection with aggregates
OrderByExpression — Column + direction
GroupByExpression — Column grouping

ActiveFlag Lifecycle Enum

Rich status model with ranged queries:

public enum ActiveFlag {
    Unknown,
    Deleted,
    Active,
    Permanent
}

Helpers:

getActiveRange() — Active to Permanent
getVisibleRangeAndUp() — Active and above
And more status range helpers

Converters

Built-in JPA attribute converters:

LocalDateAttributeConverter — LocalDate ↔ java.sql.Date
LocalDateTimeAttributeConverter — LocalDateTime ↔ java.sql.Timestamp
LocalDateTimestampAttributeConverter — LocalDate ↔ java.sql.Timestamp

Testing with Testcontainers

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class EntityAssistReactiveTest {

    private Mutiny.SessionFactory sessionFactory;

    @BeforeAll
    public void setup() {
        IGuiceContext.instance();
        JtaPersistService ps = (JtaPersistService) IGuiceContext.get(
            Key.get(PersistService.class, Names.named("entityAssistReactive")));
        ps.start();

        sessionFactory = IGuiceContext.get(
            Key.get(Mutiny.SessionFactory.class, Names.named("entityAssistReactive")));
    }

    @Test
    void roundTrip() {
        EntityClass entity = new EntityClass()
            .setId("test1")
            .setName("Test Entity");

        sessionFactory.withSession(session ->
            session.withTransaction(tx ->
                entity.builder(session).persist(entity)
            ).chain(() ->
                new EntityClass().builder(session)
                    .find("test1").get()
            ).invoke(found -> {
                assertNotNull(found);
                assertEquals("test1", found.getId());
            })
        ).replaceWithVoid();
    }
}

Best Practices

Never use await().indefinitely() in service flows; return Uni and keep composition with chain(...) / invoke(...)
Always run in Vert.x context (event loop or worker)
Prefer projections for read-heavy paths
Use setFirstResults() / setMaxResults() for pagination
Keep transactions short; chain Uni calls
Bulk delete() requires filters — use truncate() for all rows
Use stateless sessions for bulk inserts
Validate entities before persistence with validateEntity()
Filter associations with a JOIN in the WHERE clause, not session.fetch(). To restrict a result set by a related row, add the join/predicate to the builder (where(...), dot-notation path filters, or the domain helpers like withConcept(...) / withEnterprise(...) / inActiveRange()). Reserve session.fetch(...) for loading a lazy association you actually need to read — never to filter on the heap. The join keeps the predicate in a single SQL statement, avoids materialising unneeded rows, and sidesteps lazy-init hazards on the reactive session.
```
// ✅ Good — predicate pushed into SQL via a join on the WHERE clause
var qb = new Classification().builder(session);
return qb.where(qb.getAttribute("concepts.name"), Operand.Equals, conceptName)
         .inActiveRange()
         .getCount();                         // existence check, no rows materialised

// ❌ Bad — fetch the association then filter in Java
return entityService.find(session, id)
    .chain(e -> session.fetch(e.getConcepts()))
    .map(concepts -> concepts.stream().anyMatch(...));
```
Prefer getCount() over get() + null-check for existence tests — it avoids selecting and hydrating a full entity just to discover whether a row exists.
Operate on the caller's Mutiny.Session. Library/builder code must accept and use the session/transaction it is handed; never open a nested session (e.g. a second withSession/withTransaction) inside a method that already received one. Nesting sessions on the same Vert.x context triggers HR000069 (wrong-thread) and "Illegal pop()" errors and violates one-action-per-session. Establish the unit of work at the entry point.

JPMS Module

module com.entityassist {
    requires transitive com.guicedee.persistence;
    requires transitive jakarta.persistence;
    requires transitive org.hibernate.reactive;
    requires transitive io.smallrye.mutiny;

    exports com.entityassist.entities;
    exports com.entityassist.querybuilder;
    exports com.entityassist.enumerations;

    opens com.entityassist.entities to org.hibernate.orm.core, com.google.guice;
}

Required JVM module flags (runtime / jlink)

Hibernate ORM core reflectively reaches into EntityAssist's classes when bootstrapping the metamodel, but org.hibernate.orm.core does not (and must not) statically requires com.entityassist. The reverse read edge therefore has to be added at launch time. Add this flag to the application launcher (and to any jlink --add-reads/launcher options, surefire argLine, and IDE run configs):

--add-reads
org.hibernate.orm.core=com.entityassist

Without it, metamodel/attribute resolution for EntityAssist entities fails at runtime with an IllegalAccessError / does not read module error. This edge belongs to EntityAssist (it is required by any application that persists EntityAssist entities), independent of which downstream domain (e.g. ActivityMaster) is in use.

Installation

<dependency>
  <groupId>com.entityassist</groupId>
  <artifactId>entity-assist-reactive</artifactId>
</dependency>

Module Graph

com.entityassist
 ├── com.guicedee.persistence
 ├── com.guicedee.client
 ├── jakarta.persistence
 ├── org.hibernate.reactive
 ├── org.hibernate.orm.core
 ├── io.smallrye.mutiny
 ├── io.vertx.sql.client.pg
 └── jakarta.xml.bind

References

Module: com.entityassist
Hibernate Reactive: 7.x
Mutiny: 1.x
Vert.x: 5.x
Java: 25+
License: Apache 2.0

Agent Skills: EntityAssist Reactive

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