Author: hardy.ferentschik Date: 2010-06-22 12:36:45 -0400 (Tue, 22 Jun 2010) New Revision: 19782 Modified: core/trunk/documentation/manual/src/main/docbook/en-US/content/basic_mapping.xml core/trunk/documentation/manual/src/main/docbook/en-US/content/collection_mapping.xml Log: HHH-5149 Modified: core/trunk/documentation/manual/src/main/docbook/en-US/content/basic_mapping.xml =================================================================== --- core/trunk/documentation/manual/src/main/docbook/en-US/content/basic_mapping.xml 2010-06-22 16:30:24 UTC (rev 19781) +++ core/trunk/documentation/manual/src/main/docbook/en-US/content/basic_mapping.xml 2010-06-22 16:36:45 UTC (rev 19782) @@ -5198,7 +5198,7 @@ </section> <section id="mapping-declaration-key"> - <title>Key</title> + <title id="section.key">Key</title> <para>The <literal>&lt;key&gt;</literal> element is featured a few times within this guide. It appears anywhere the parent mapping Modified: core/trunk/documentation/manual/src/main/docbook/en-US/content/collection_mapping.xml =================================================================== --- core/trunk/documentation/manual/src/main/docbook/en-US/content/collection_mapping.xml 2010-06-22 16:30:24 UTC (rev 19781) +++ core/trunk/documentation/manual/src/main/docbook/en-US/content/collection_mapping.xml 2010-06-22 16:36:45 UTC (rev 19782) @@ -33,34 +33,20 @@ <section id="collections-persistent" revision="3"> <title>Persistent collections</title> - <para>Of course Hibernate also allows to persist collections. These + <para>Naturally Hibernate also allows to persist collections. These persistent collections can contain almost any other Hibernate type, including: basic types, custom types, components and references to other - entities. This is an important distinction. An object in a collection - might be handled with "value" semantics (its life cycle fully depends on - the collection owner), or it might be a reference to another entity with - its own life cycle. In the latter case, only the "link" between the two - objects is considered to be a state held by the collection.</para> + entities. The distinction between value and reference semantics is in this + context very important. An object in a collection might be handled with + "value" semantics (its life cycle fully depends on the collection owner), + or it might be a reference to another entity with its own life cycle. In + the latter case, only the "link" between the two objects is considered to + be a state held by the collection.</para> <para>As a requirement persistent collection-valued fields must be - declared as an interface type. For example:</para> - - <example id="example-collection-values-field"> - <title>Persistent collection-valued fields must be interfaces</title> - - <programlisting role="JAVA">public class Product { - private String serialNumber; - private Set parts = new HashSet(); - - public Set getParts() { return parts; } - void setParts(Set parts) { this.parts = parts; } - - public String getSerialNumber() { return serialNumber; } - void setSerialNumber(String sn) { serialNumber = sn; } -}</programlisting> - </example> - - <para>The actual interface might be <literal>java.util.Set</literal>, + declared as an interface type (see <xref + linkend="example.collection.mapping.annotations" />). The actual interface + might be <literal>java.util.Set</literal>, <literal>java.util.Collection</literal>, <literal>java.util.List</literal>, <literal>java.util.Map</literal>, <literal>java.util.SortedSet</literal>, @@ -68,15 +54,15 @@ like" means you will have to write an implementation of <literal>org.hibernate.usertype.UserCollectionType</literal>).</para> - <para>Notice how in <xref linkend="example-collection-values-field" /> the - instance variable <literal>parts</literal> was initialized with an - instance of <literal>HashSet</literal>. This is the best way to initialize - collection valued properties of newly instantiated (non-persistent) - instances. When you make the instance persistent, by calling - <literal>persist()</literal>, Hibernate will actually replace the - <literal>HashSet</literal> with an instance of Hibernate's own - implementation of <literal>Set</literal>. Be aware of the following - error:</para> + <para>Notice how in <xref + linkend="example.collection.mapping.annotations" /> the instance variable + <literal>parts</literal> was initialized with an instance of + <literal>HashSet</literal>. This is the best way to initialize collection + valued properties of newly instantiated (non-persistent) instances. When + you make the instance persistent, by calling <literal>persist()</literal>, + Hibernate will actually replace the <literal>HashSet</literal> with an + instance of Hibernate's own implementation of <literal>Set</literal>. Be + aware of the following error:</para> <example> <title>Hibernate uses its own collection implementations</title> @@ -108,23 +94,25 @@ Hibernate does not distinguish between a null collection reference and an empty collection.</para> - <para>Use persistent collections the same way you use ordinary Java - collections. However, please ensure you understand the semantics of - bidirectional associations (see <xref - linkend="collections-bidirectional" />).</para> + <note> + <para>Use persistent collections the same way you use ordinary Java + collections. However, ensure you understand the semantics of + bidirectional associations (see <xref + linkend="collections-bidirectional" />).</para> + </note> </section> <section id="collections-mapping" revision="4"> - <title>Collection mappings</title> + <title>How to map collections</title> <para>Using annotations you can map <classname>Collection</classname>s, - <classname>Lists</classname>, <classname>Maps</classname> and - <classname>Sets</classname> of associated entities using @OneToMany and + <classname>List</classname>s, <classname>Map</classname>s and + <classname>Set</classname>s of associated entities using @OneToMany and @ManyToMany. For collections of a basic or embeddable type use @ElementCollection. In the simplest case a collection mapping looks like this:</para> - <example> + <example id="example.collection.mapping.annotations"> <title>Collection mapping using annotations</title> <programlisting role="JAVA">@Entity @@ -149,14 +137,11 @@ }</programlisting> </example> - <para>The <literal>@OneToMany</literal> and <literal>@ManyToOne</literal> - annotations have several options and there are other annotations which can - be used in in combination with these annotations. But lets first see how - collections are mapped using Hibernate mapping files. Here the situation - is more complex than in the annotation case, since the mapping element - used for mapping a collection depends upon the type of interface. For - example, a <literal>&lt;set&gt;</literal> element is used for mapping - properties of type <literal>Set</literal>.</para> + <para>Lets have a look how collections are mapped using Hibernate mapping + files. Here the first step is to chose the right mapping element, because + it depends on the type of interface. For example, a + <literal>&lt;set&gt;</literal> element is used for mapping properties of + type <literal>Set</literal>.</para> <example floatstyle="" id="example.collections.set"> <title>Mapping a Set using &lt;set&gt;</title> @@ -189,11 +174,11 @@ </listitem> </itemizedlist> - <para>The <literal>&lt;one-to-many&gt;</literal> tag has the following - options.</para> + <para>Looking closer at the used <literal>&lt;one-to-many&gt;</literal> + tag we see that it has the following options.</para> <example> - <title>options of &lt;one-to-many&gt; tag</title> + <title>options of &lt;one-to-many&gt; element</title> <programlistingco role="XML"> <areaspec> @@ -246,8 +231,8 @@ <literal>&lt;key&gt;</literal> mapping <literal>not-null="true"</literal> or <emphasis>use a bidirectional association</emphasis> with the collection mapping marked - <literal>inverse="true"</literal>. See the discussion of bidirectional - associations later in this chapter for more information.</para> + <literal>inverse="true"</literal>. See <xref + linkend="collections-bidirectional" />.</para> </warning> <para>Apart from the <literal>&lt;set&gt; </literal>tag as shown in <xref @@ -411,12 +396,16 @@ </programlistingco> </example> + <para>After exploring the basic mapping of collections in the preceding + paragraphs we will now focus details like physical mapping considerations, + indexed collections and collections of value types.</para> + <section id="collections-foreignkeys"> <title>Collection foreign keys</title> - <para>Collection instances are distinguished in the database by the - foreign key of the entity that owns the collection. This foreign key is - referred to as the <emphasis>collection key column</emphasis>, or + <para>On the database level collection instances are distinguished by + the foreign key of the entity that owns the collection. This foreign key + is referred to as the <emphasis>collection key column</emphasis>, or columns, of the collection table. The collection key column is mapped by the <literal>@JoinColumn</literal> annotation respectively the <literal>&lt;key&gt;</literal> XML element.</para> @@ -442,8 +431,8 @@ <programlisting role=&quot;Java&quot;&gt;(a)OnDelete(action=OnDeleteAction.CASCADE)&lt;/programlisting&gt; - <para>See <xref linkend="section-key" /> for more information about the - <literal>&lt;key&gt;</literal> element.</para> + <para>See <xref lang="" linkend="section.key" /> for more information + about the <literal>&lt;key&gt;</literal> element.</para> </section> <section id="collections-indexed">