org.hibernate.NaturalIdLoadAccess.java Source code

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Here is the source code for org.hibernate.NaturalIdLoadAccess.java

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate;

import java.io.Serializable;
import java.util.Optional;

/**
 * Loads an entity by its natural identifier.
 * 
 * @author Eric Dalquist
 * @author Steve Ebersole
 *
 * @see org.hibernate.annotations.NaturalId
 */
public interface NaturalIdLoadAccess<T> {
    /**
     * Specify the {@link LockOptions} to use when retrieving the entity.
     *
     * @param lockOptions The lock options to use.
     *
     * @return {@code this}, for method chaining
     */
    NaturalIdLoadAccess<T> with(LockOptions lockOptions);

    /**
     * Add a NaturalId attribute value.
     * 
     * @param attributeName The entity attribute name that is marked as a NaturalId
     * @param value The value of the attribute
     *
     * @return {@code this}, for method chaining
     */
    NaturalIdLoadAccess<T> using(String attributeName, Object value);

    /**
     * For entities with mutable natural ids, should Hibernate perform "synchronization" prior to performing
     * lookups?  The default is to perform "synchronization" (for correctness).
     * <p/>
     * "synchronization" here indicates updating the natural-id -> pk cross reference maintained as part of the
     * session.  When enabled, prior to performing the lookup, Hibernate will check all entities of the given
     * type associated with the session to see if its natural-id values have changed and, if so, update the
     * cross reference.  There is a performance impact associated with this, so if application developers are
     * certain the natural-ids in play have not changed, this setting can be disabled to circumvent that impact.
     * However, disabling this setting when natural-ids values have changed can result in incorrect results!
     *
     * @param enabled Should synchronization be performed?  {@code true} indicates synchronization will be performed;
     * {@code false} indicates it will be circumvented.
     *
     * @return {@code this}, for method chaining
     */
    NaturalIdLoadAccess<T> setSynchronizationEnabled(boolean enabled);

    /**
     * Return the persistent instance with the natural id value(s) defined by the call(s) to {@link #using}.  This
     * method might return a proxied instance that is initialized on-demand, when a non-identifier method is accessed.
     *
     * You should not use this method to determine if an instance exists; to check for existence, use {@link #load}
     * instead.  Use this only to retrieve an instance that you assume exists, where non-existence would be an
     * actual error.
     *
     * @return the persistent instance or proxy
     */
    T getReference();

    /**
     * Return the persistent instance with the natural id value(s) defined by the call(s) to {@link #using}, or
     * {@code null} if there is no such persistent instance.  If the instance is already associated with the session,
     * return that instance, initializing it if needed.  This method never returns an uninitialized instance.
     *
     * @return The persistent instance or {@code null} 
     */
    T load();

    /**
     * Same semantic as {@link #load} except that here {@link Optional} is returned to
     * handle nullability.
     *
     * @return The persistent instance, if one, wrapped in Optional
     */
    Optional<T> loadOptional();

}