HHH-4940 : Document immutable/read-only entity and immutable collection functionality
git-svn-id: https://svn.jboss.org/repos/hibernate/core/trunk@19108 1b8cb986-b30d-0410-93ca-fae66ebed9b2
This commit is contained in:
Gail Badner
parent
98628c4a0e
commit
039bb48ccf
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<xi:include href="content/inheritance_mapping.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
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<xi:include href="content/session_api.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
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<xi:include href="content/readonly.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
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<xi:include href="content/transactions.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
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<xi:include href="content/events.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
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<xi:include href="content/batch.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
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@ -0,0 +1,858 @@
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<?xml version='1.0' encoding="UTF-8"?>
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<!--
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~ Hibernate, Relational Persistence for Idiomatic Java
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~
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~ Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
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~ indicated by the @author tags or express copyright attribution
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~ statements applied by the authors. All third-party contributions are
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~ distributed under license by Red Hat Middleware LLC.
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~
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~ This copyrighted material is made available to anyone wishing to use, modify,
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~ copy, or redistribute it subject to the terms and conditions of the GNU
|
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~ Lesser General Public License, as published by the Free Software Foundation.
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~
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~ This program is distributed in the hope that it will be useful,
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~ but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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~ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
|
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~ for more details.
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~
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~ You should have received a copy of the GNU Lesser General Public License
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~ along with this distribution; if not, write to:
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~ Free Software Foundation, Inc.
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~ 51 Franklin Street, Fifth Floor
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~ Boston, MA 02110-1301 USA
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-->
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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY % BOOK_ENTITIES SYSTEM "../HIBERNATE_-_Relational_Persistence_for_Idiomatic_Java.ent">
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%BOOK_ENTITIES;
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]>
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<chapter id="readonly">
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<title>Read-only entities</title>
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<important>
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<para>
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Hibernate's treatment of <emphasis>read-only</emphasis> entities may
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differ from what you may have encountered elsewhere. Incorrect usage
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may cause unexpected results.
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</para>
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</important>
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<para>
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When an entity is read-only:
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<itemizedlist>
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<listitem>
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<para>
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Hibernate does not dirty-check the entity's simple
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properties or single-ended associations;
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</para>
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</listitem>
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<listitem>
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<para>
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Hibernate will not update simple properties or updatable
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single-ended associations;
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</para>
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</listitem>
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<listitem>
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<para>
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Hibernate will not update the version of the read-only
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entity if only simple properties or single-ended
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updatable associations are changed;
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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In some ways, Hibernate treats read-only entities the same as entities that are
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not read-only:
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<itemizedlist>
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<listitem>
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<para>
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Hibernate cascades operations to associations as
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defined in the entity mapping.
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</para>
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</listitem>
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<listitem>
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<para>
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Hibernate updates the version if the entity has a
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collection with changes that dirties the entity;
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</para>
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</listitem>
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<listitem>
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<para>
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A read-only entity can be deleted.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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Even if an entity is not read-only, its collection association can
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be affected if it contains a read-only entity.
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</para>
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<para>
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For details about the affect of read-only entities on different
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property and association types, see
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<xref linkend="readonly-proptypes"/>.
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</para>
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<para>
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For details about how to make entities read-only, see
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<xref linkend="readonly-api"/>
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</para>
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<para>
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Hibernate does some optimizing for read-only entities:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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It saves execution time by not dirty-checking simple properties or
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single-ended associations.
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</para>
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</listitem>
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<listitem>
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<para>
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It saves memory by deleting database snapshots.
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</para>
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</listitem>
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</itemizedlist>
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<section id="readonly-api">
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<title>Making persistent entities read-only</title>
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<para>
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Only persistent entities can be made read-only. Transient and
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detached entities must be put in persistent state before they
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can be made read-only.
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</para>
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<para>
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Hibernate provides the following ways to make persistent entities read-only:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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you can map an entity class as <emphasis>immutable</emphasis>;
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when an entity of an immutable class is made persistent,
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Hibernate automatically makes it read-only.
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see <xref linkend="readonly-api-immutable"/> for details
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</para>
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</listitem>
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<listitem>
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<para>
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you can change a default so that entities loaded
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into the session by Hibernate are automatically
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made read-only; see <xref linkend="readonly-api-loaddefault"/> for details
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</para>
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</listitem>
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<listitem>
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<para>
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you can make an HQL query or criteria read-only so
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that entities loaded when the query or criteria executes,
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scrolls, or iterates, are automatically
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made read-only; see <xref linkend="readonly-api-querycriteria"/> for details
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</para>
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</listitem>
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<listitem>
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<para>
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you can make a persistent entity that is already in the
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in the session read-only; see
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<xref linkend="readonly-api-entity"/> for details
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</para>
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</listitem>
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</itemizedlist>
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<section id="readonly-api-immutable">
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<title>Entities of immutable classes</title>
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<para>
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When an entity instance of an immutable class is made
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persistent, Hibernate automatically makes it read-only.
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</para>
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<para>
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An entity of an immutable class can created
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and deleted the same as an entity of a mutable class.
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</para>
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<para>
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Hibernate treats a persistent entity of an immutable
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class the same way as a read-only persistent entity
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of a mutable class. The only exception is that
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Hibernate will not allow an entity of an immutable
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class to be changed so it is not read-only.
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</para>
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</section>
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<section id="readonly-api-loaddefault">
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<title>Loading persistent entities as read-only</title>
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<note>
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<para>
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Entities of immutable classes are automatically loaded
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as read-only.
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</para>
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</note>
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<para>
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To change the default behavior so Hibernate loads entity
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instances of mutable classes into the session and automatically
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makes them read-only, call:
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</para>
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<programlisting role="Java">Session.setDefaultReadOnly( true );</programlisting>
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<para>
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To change the default back so entities loaded by Hibernate are not
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made read-only, call:
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</para>
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<programlisting role="Java">Session.setDefaultReadOnly( false );</programlisting>
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<para>
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You can determine the current setting by calling:
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</para>
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<programlisting role="Java">Session.isDefaultReadOnly();</programlisting>
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<para>
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If Session.isDefaultReadOnly() returns true, entities loaded by
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the following are automatically made read-only:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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Session.load()
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</para>
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</listitem>
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<listitem>
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<para>
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Session.get()
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</para>
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</listitem>
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<listitem>
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<para>
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Session.merge()
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</para>
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</listitem>
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<listitem>
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<para>
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executing, scrolling, or iterating HQL queries and
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criteria; to override this setting for a particular
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HQL query or criteria see
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<xref linkend="readonly-api-querycriteria"/>
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</para>
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</listitem>
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</itemizedlist>
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<para>
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Changing this default has no effect on:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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persistent entities already in the session when the
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default was changed
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</para>
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</listitem>
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<listitem>
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<para>
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persistent entities that are refreshed via
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Session.refresh(); a refreshed persistent
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entity will only be read-only if it was
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read-only before refreshing
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</para>
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</listitem>
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<listitem>
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<para>
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persistent entities added by the application via
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Session.persist(), Session.save(), and Session.update()
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Session.saveOrUpdate()
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</para>
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</listitem>
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</itemizedlist>
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</section>
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<section id="readonly-api-querycriteria">
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<title>Loading read-only entities from an HQL query/criteria</title>
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<note>
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<para>
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Entities of immutable classes are automatically loaded
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as read-only.
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</para>
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</note>
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<para>
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If Session.isDefaultReadOnly() returns false (the default)
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when an HQL query or criteria executes, then entities
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and proxies of mutable classes loaded by the query will
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not be read-only.
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</para>
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<para>
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You can override this behavior so that entities and proxies loaded
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by an HQL query or criteria are automatically made read-only.
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</para>
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<para>
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For an HQL query, call:
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</para>
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<programlisting role="Java">Query.setReadOnly( true );</programlisting>
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<para>
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<literal>Query.setReadOnly( true )</literal> must be called before
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<literal>Query.list()</literal>, <literal>Query.uniqueResult()</literal>,
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<literal>Query.scroll()</literal>, or <literal>Query.iterate()</literal>
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</para>
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<para>
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For an HQL criteria, call:
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</para>
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<programlisting role="Java">Criteria.setReadOnly( true );</programlisting>
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<para>
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<literal>Criteria.setReadOnly( true )</literal> must be called before
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<literal>Criteria.list()</literal>, <literal>Criteria.uniqueResult()</literal>,
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or <literal>Criteria.scroll()</literal>
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</para>
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<para>
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Entities and proxies that exist in the session before being returned
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by an HQL query or criteria are not affected.
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</para>
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<para>
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Uninitialized persistent collections returned by the query are
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not affected. Later, when the collection is initialized,
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entities loaded into the session will be read-only if
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Session.isDefaultReadOnly() returns true.
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</para>
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<para>
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Using <literal>Query.setReadOnly( true )</literal> or
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<literal>Criteria.setReadOnly( true )</literal> works well
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when a single HQL query or criteria loads all the entities and
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intializes all the proxies and collections that the application
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needs to be read-only.
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</para>
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<para>
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When it is not possible to load and initialize all
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necessary entities in a single query or criteria,
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you can temporarily change the session default to load
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entities as read-only before the query is executed.
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Then you can explicitly initialize proxies and collections
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before restoring the session default.
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</para>
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<programlisting role="Java">
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Session session = factory.openSession();
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Transaction tx = session.beginTransaction();
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setDefaultReadOnly( true );
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Contract contract =
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( Contract ) session.createQuery(
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"from Contract where customerName = 'Sherman'" )
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.uniqueResult();
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Hibernate.initialize( contract.getPlan() );
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Hibernate.initialize( contract.getVariations() );
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Hibernate.initialize( contract.getNotes() );
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setDefaultReadOnly( false );
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...
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tx.commit();
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session.close();
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</programlisting>
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<para>
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If Session.isDefaultReadOnly() returns true, then you can
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use Query.setReadOnly( false ) and Criteria.setReadOnly( false )
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to override this session setting and load entities that are
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not read-only.
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</para>
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</section>
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<section id="readonly-api-entity">
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<title>Making a persistent entity read-only</title>
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<note>
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<para>
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Persistent entities of immutable classes are automatically
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made read-only.
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</para>
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</note>
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<para>
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To make a persistent entity or proxy read-only, call:
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</para>
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<programlisting>Session.setReadOnly(entityOrProxy, true)</programlisting>
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<para>
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To change a read-only entity or proxy of a mutable class so
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it is no longer read-only, call:
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</para>
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<programlisting>Session.setReadOnly(entityOrProxy, false)</programlisting>
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<important>
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<para>
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When a read-only entity or proxy is changed so it is no longer
|
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read-only, Hibernate assumes that the current state of the
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read-only entity is consistent with its database representation.
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If this is not true, then any non-flushed changes made before
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or while the entity was read-only, will be ignored.
|
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</para>
|
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</important>
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|
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<para>
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To throw away non-flushed changes and make the persistent entity
|
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consistent with its database representation, call:
</para>
|
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<programlisting role="Java">session.refresh( entity );</programlisting>
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|
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<para>
|
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To flush changes made before or while the entity
|
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was read-only and make the database representation
|
||||
consistent with the current state of the persistent
|
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entity:
|
||||
</para>
|
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<programlisting role="Java">
|
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// evict the read-only entity so it is detached
|
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session.evict( entity );
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|
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// make the detached entity (with the non-flushed changes) persistent
|
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session.update( entity );
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|
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// now entity is no longer read-only and its changes can be flushed
|
||||
s.flush();
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||||
</programlisting>
|
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</section>
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</section>
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<section id="readonly-proptypes">
|
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<title>Read-only affect on property type</title>
|
||||
|
||||
<para>
|
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The following table summarizes how different property types are
|
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affected by making an entity read-only.
|
||||
</para>
|
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|
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<table frame="topbot" id="readonly-proptype-summary">
|
||||
<title>Affect of read-only entity on property types</title>
|
||||
<tgroup cols="2">
|
||||
<colspec colwidth="1*"/>
|
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<colspec colwidth="1*"/>
|
||||
<thead>
|
||||
<row>
|
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<entry>Property/Association Type</entry>
|
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<entry>Changes flushed to DB?</entry>
|
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</row>
|
||||
</thead>
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>
|
||||
Simple
|
||||
<para>
|
||||
(<xref linkend="readonly-proptypes-simple"/>)
|
||||
</para>
|
||||
</entry>
|
||||
<entry>no*</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>
|
||||
<para>Unidirectional one-to-one</para>
|
||||
<para>Unidirectional many-to-one</para>
|
||||
<para>
|
||||
(<xref linkend="readonly-proptypes-singleended-unidir"/>)
|
||||
</para>
|
||||
</entry>
|
||||
|
||||
<entry>
|
||||
<para>no*</para>
|
||||
<para>no*</para>
|
||||
</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>
|
||||
<para>Unidirectional one-to-many</para>
|
||||
<para>Unidirectional many-to-many</para>
|
||||
<para>
|
||||
(<xref linkend="readonly-proptypes-manyended-unidir"/>)
|
||||
</para>
|
||||
</entry>
|
||||
<entry>
|
||||
<para>yes</para>
|
||||
<para>yes</para>
|
||||
</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>
|
||||
<para>Bidirectional one-to-one</para>
|
||||
<para>
|
||||
(<xref linkend="readonly-proptypes-onetoone-bidir"/>)
|
||||
</para>
|
||||
</entry>
|
||||
<entry>only if the owning entity is not read-only*</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>
|
||||
<para>Bidirectional one-to-many/many-to-one</para>
|
||||
<para>inverse collection</para>
|
||||
<para>non-inverse collection</para>
|
||||
<para>
|
||||
(<xref linkend="readonly-proptypes-onetomany-manytoone"/>)
|
||||
</para>
|
||||
</entry>
|
||||
<entry>
|
||||
<para> </para>
|
||||
<para>only added/removed entities that are not read-only*</para>
|
||||
<para>yes</para>
|
||||
</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>
|
||||
<para>Bidirectional many-to-many</para>
|
||||
<para>
|
||||
(<xref linkend="readonly-proptypes-manytomany-bidir"/>)
|
||||
</para>
|
||||
</entry>
|
||||
<entry>yes</entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</table>
|
||||
|
||||
<para>
|
||||
* Behavior is different when the entity having the property/association
|
||||
is read-only, compared to when it is not read-only.
|
||||
</para>
|
||||
|
||||
<section id="readonly-proptypes-simple">
|
||||
<title>Simple properties</title>
|
||||
|
||||
<para>
|
||||
When a persistent object is read-only, Hibernate does not
|
||||
dirty-check simple properties.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Hibernate will not synchronize simple property state changes
|
||||
to the database. If you have automatic versioning, Hibernate
|
||||
will not increment the version if any simple properties change.
|
||||
</para>
|
||||
|
||||
<programlisting role="Java">
|
||||
Session session = factory.openSession();
|
||||
Transaction tx = session.beginTransaction();
|
||||
|
||||
// get a contract and make it read-only
|
||||
Contract contract = ( Contract ) session.get( Contract.class, contractId );
|
||||
session.setReadOnly( contract, true );
|
||||
|
||||
// contract.getCustomerName() is "Sherman"
|
||||
contract.setCustomerName( "Yogi" );
|
||||
tx.commit();
|
||||
|
||||
tx = session.beginTransaction();
|
||||
|
||||
contract = ( Contract ) session.get( Contract.class, contractId );
|
||||
// contract.getCustomerName() is still "Sherman"
|
||||
...
|
||||
tx.commit();
|
||||
session.close();
|
||||
</programlisting>
|
||||
|
||||
</section>
|
||||
|
||||
<section id="readonly-prop-types-unidir">
|
||||
<title>Unidirectional associations</title>
|
||||
|
||||
<section id="readonly-proptypes-singleended-unidir">
|
||||
<title>Unidirectional one-to-one and many-to-one</title>
|
||||
|
||||
<para>
|
||||
Hibernate treats unidirectional one-to-one and many-to-one
|
||||
associations in the same way when the owning entity is
|
||||
read-only.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
We use the term <emphasis>unidirectional single-ended
|
||||
association</emphasis> when referring to functionality
|
||||
that is common to unidirectional one-to-one and many-to-one
|
||||
associations.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Hibernate does not dirty-check unidirectional single-ended
|
||||
associations when the owning entity is read-only.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
If you change a read-only entity's reference to a
|
||||
unidirectional single-ended association to null,
|
||||
or to refer to a different entity, that change
|
||||
will not be flushed to the database.
|
||||
</para>
|
||||
|
||||
<note>
|
||||
<para>
|
||||
If an entity is of an immutable class,
|
||||
then its references to unidirectional single-ended
|
||||
associations must be assigned when that
|
||||
entity is first created. Because the entity is
|
||||
automatically made read-only, these references can
|
||||
not be updated.
|
||||
</para>
|
||||
</note>
|
||||
|
||||
<para>
|
||||
If automatic versioning is used, Hibernate will not
|
||||
increment the version due to local changes to
|
||||
unidirectional single-ended associations.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
In the following examples, Contract has a unidirectional
|
||||
many-to-one association with Plan. Contract cascades save and
|
||||
update operations to the association.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The following shows that changing a read-only entity's
|
||||
many-to-one association reference to null has no effect
|
||||
on the entity's database representation.
|
||||
</para>
|
||||
|
||||
<programlisting role="Java">// get a contract with an existing plan;
|
||||
// make the contract read-only and set its plan to null
|
||||
tx = session.beginTransaction();
|
||||
Contract contract = ( Contract ) session.get( Contract.class, contractId );
|
||||
session.setReadOnly( contract, true );
|
||||
contract.setPlan( null );
|
||||
tx.commit();
|
||||
|
||||
// get the same contract
|
||||
tx = session.beginTransaction();
|
||||
contract = ( Contract ) session.get( Contract.class, contractId );
|
||||
|
||||
// contract.getPlan() still refers to the original plan;
|
||||
|
||||
tx.commit();
|
||||
session.close();</programlisting>
|
||||
|
||||
<para>
|
||||
The following shows that, even though
|
||||
an update to a read-only entity's many-to-one
|
||||
association has no affect on the entity's
|
||||
database representation, flush still cascades
|
||||
the save-update operation to the locally
|
||||
changed association.
|
||||
</para>
|
||||
|
||||
<programlisting role="Java">// get a contract with an existing plan;
|
||||
// make the contract read-only and change to a new plan
|
||||
tx = session.beginTransaction();
|
||||
Contract contract = ( Contract ) session.get( Contract.class, contractId );
|
||||
session.setReadOnly( contract, true );
|
||||
Plan newPlan = new Plan( "new plan"
|
||||
contract.setPlan( newPlan);
|
||||
tx.commit();
|
||||
|
||||
// get the same contract
|
||||
tx = session.beginTransaction();
|
||||
contract = ( Contract ) session.get( Contract.class, contractId );
|
||||
newPlan = ( Contract ) session.get( Plan.class, newPlan.getId() );
|
||||
|
||||
// contract.getPlan() still refers to the original plan;
|
||||
// newPlan is non-null because it was persisted when
|
||||
// the previous transaction was committed;
|
||||
|
||||
tx.commit();
|
||||
session.close();</programlisting>
|
||||
|
||||
</section>
|
||||
|
||||
<section id="readonly-proptypes-manyended-unidir">
|
||||
<title>Unidirectional one-to-many and many-to-many</title>
|
||||
|
||||
<para>
|
||||
Hibernate treats unidirectional one-to-many
|
||||
and many-to-many associations owned by a read-only
|
||||
entity the same as when owned by an entity that is not
|
||||
read-only.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Hibernate dirty-checks unidirectional one-to-many and
|
||||
many-to-many associations;
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The collection can contain entities that
|
||||
are read-only, as well as entities
|
||||
that are not read-only.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Entities can be added and removed from the
|
||||
collection; changes are flushed to the database.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
If automatic versioning is used, Hibernate will
|
||||
update the version due to changes in the collection
|
||||
if they dirty the owning entity.
|
||||
</para>
|
||||
|
||||
</section>
|
||||
|
||||
</section>
|
||||
|
||||
<section id="readonly-proptypes-bidir">
|
||||
<title>Bidirectional associations</title>
|
||||
|
||||
<section id="readonly-proptypes-onetoone-bidir">
|
||||
<title>Bidirectional one-to-one</title>
|
||||
|
||||
<para>
|
||||
If a read-only entity owns a bidirectional
|
||||
one-to-one association:
|
||||
</para>
|
||||
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>
|
||||
Hibernate does not dirty-check the association.
|
||||
</para>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<para>
|
||||
updates that change the association reference
|
||||
to null or to refer to a different entity
|
||||
will not be flushed to the database.
|
||||
</para>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<para>
|
||||
If automatic versioning is used, Hibernate will not
|
||||
increment the version due to local changes to
|
||||
the association.
|
||||
</para>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
|
||||
<note>
|
||||
<para>
|
||||
If an entity is of an immutable class,
|
||||
and it owns a bidirectional one-to-one
|
||||
association, then its reference must be
|
||||
assigned when that entity is first created.
|
||||
Because the entity is automatically made
|
||||
read-only, these references cannot be updated.
|
||||
</para>
|
||||
</note>
|
||||
|
||||
<para>
|
||||
When the owner is not read-only, Hibernate treats
|
||||
an association with a read-only entity the same
|
||||
as when the association is with an entity that is
|
||||
not read-only.
|
||||
</para>
|
||||
|
||||
</section>
|
||||
|
||||
<section id="readonly-proptypes-onetomany-manytoone">
|
||||
<title>Bidirectional one-to-many/many-to-one</title>
|
||||
|
||||
<para>
|
||||
A read-only entity has no impact on a bidirectional
|
||||
one-to-many/many-to-one association if:
|
||||
</para>
|
||||
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>
|
||||
the read-only entity is on the one-to-many side
|
||||
using an inverse collection;
|
||||
</para>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<para>
|
||||
the read-only entity is on the one-to-many side
|
||||
using a non-inverse collection;
|
||||
</para>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<para>
|
||||
the one-to-many side uses a non-inverse collection
|
||||
that contains the read-only entity
|
||||
</para>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
|
||||
<para>
|
||||
When the one-to-many side uses an inverse collection:
|
||||
</para>
|
||||
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>
|
||||
a read-only entity can only be added to the collection
|
||||
when it is created;
|
||||
</para>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<para>
|
||||
a read-only entity can only be removed from the
|
||||
collection by an orphan delete or by explicitly
|
||||
deleting the entity.
|
||||
</para>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
|
||||
</section>
|
||||
|
||||
<section id="readonly-proptypes-manytomany-bidir">
|
||||
<title>Bidirectional many-to-many</title>
|
||||
<para>
|
||||
Hibernate treats bidirectional many-to-many
|
||||
associations owned by a read-only entity the
|
||||
same as when owned by an entity that is not
|
||||
read-only.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Hibernate dirty-checks bidirectional many-to-many
|
||||
associations.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The collection on either side of the association
|
||||
can contain entities that are read-only, as well
|
||||
as entities that are not read-only.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Entities are added and removed from both sides
|
||||
of the collection; changes are flushed to the
|
||||
database.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
If automatic versioning is used, Hibernate will
|
||||
update the version due to changes in both sides of
|
||||
the collection if they dirty the entity owning the
|
||||
respective collections.
|
||||
</para>
|
||||
|
||||
</section>
|
||||
|
||||
</section>
|
||||
</section>
|
||||
</chapter>
|
||||
Loading…
Reference in New Issue