org.lenskit.data.dao

Class AbstractDataAccessObject

java.lang.Object

org.lenskit.data.dao.AbstractDataAccessObject

All Implemented Interfaces:

DataAccessObject

Direct Known Subclasses:

EntityCollectionDAO

public abstract class AbstractDataAccessObject
extends java.lang.Object
implements DataAccessObject

Helper class to make it easier to create DAOs. This base class implements several of the DAO convenience methods in terms of the master DataAccessObject.streamEntities(EntityQuery) method, so that DAO implementers only need to translate EntityQuery objects into their underlying query framework (collection predicates, Jooq queries, HQL, or whatever).

Constructor Summary

Constructors

Constructor and Description
AbstractDataAccessObject()

Method Summary

Modifier and Type	Method and Description
<V extends Entity> Query<V>	query(java.lang.Class<V> type) Start a query for a particular type using the fluent query interface.
Query<Entity>	query(EntityType type) Start a query using the fluent query interface.
ObjectStream<Entity>	streamEntities(EntityType type) Stream all entities of a particular type.
<E extends Entity> ObjectStream<IdBox<java.util.List<E>>>	streamEntityGroups(EntityQuery<E> query, TypedName<java.lang.Long> grpCol) Stream entities in response to a query, grouping them by a long ID.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.lenskit.data.dao.DataAccessObject

getEntityIds, getEntityTypes, lookupEntity, lookupEntity, streamEntities

Constructor Detail

AbstractDataAccessObject

public AbstractDataAccessObject()

Method Detail

query

public Query<Entity> query(EntityType type)

Description copied from interface: DataAccessObject

Start a query using the fluent query interface.

Specified by:

query in interface DataAccessObject

Parameters:

type - The type of entity to retrieve.

Returns:

The query.

query

public <V extends Entity> Query<V> query(java.lang.Class<V> type)

Start a query for a particular type using the fluent query interface. This method looks up the entity type using the DefaultEntityType annotation on the view class.

This implementation uses an internal Query implementation to prepare queries for DataAccessObject.streamEntities(EntityQuery) and streamEntityGroups(EntityQuery, TypedName).

Specified by:

query in interface DataAccessObject

Parameters:

type - The view class type.

Returns:

The query.

streamEntities

public ObjectStream<Entity> streamEntities(EntityType type)

Stream all entities of a particular type.

This implementation delegates to DataAccessObject.streamEntities(EntityQuery)

Specified by:

streamEntities in interface DataAccessObject

Parameters:

type - The entity type.

Returns:

The stream of the entities.

streamEntityGroups

public <E extends Entity> ObjectStream<IdBox<java.util.List<E>>> streamEntityGroups(EntityQuery<E> query,
                                                                                    TypedName<java.lang.Long> grpCol)

Stream entities in response to a query, grouping them by a long ID.

This implementation delegates to streamEntities(EntityType) and groups the result.

Specified by:

streamEntityGroups in interface DataAccessObject

Parameters:

query - The query.

grpCol - The column to group by.

Returns:

The stream of the entities.