brj 2005/01/15 05:08:36
Modified: src/doc/forrest/src/documentation/content/xdocs/docu/guides
basic-technique.xml
Log:
added description of non-pk-based relationships
Revision Changes Path
1.3 +146 -16
db-ojb/src/doc/forrest/src/documentation/content/xdocs/docu/guides/basic-technique.xml
Index: basic-technique.xml
===================================================================
RCS file:
/home/cvs/db-ojb/src/doc/forrest/src/documentation/content/xdocs/docu/guides/basic-technique.xml,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- basic-technique.xml 30 Jun 2004 15:36:50 -0000 1.2
+++ basic-technique.xml 15 Jan 2005 13:08:36 -0000 1.3
@@ -22,7 +22,7 @@
<title>Basic Technique</title>
<authors>
<person name="Thomas Mahler" email="[EMAIL PROTECTED]"/>
- <person name="Jakob Braeuchli" email="[EMAIL PROTECTED]"/>
+ <person name="Jakob Braeuchi" email="[EMAIL PROTECTED]"/>
<person name="Armin Waibel" email="[EMAIL PROTECTED]"/>
</authors>
</header>
@@ -100,18 +100,24 @@
These elements define foreign key attributes.
The element
<source><![CDATA[
- <foreignkey field-ref="productGroupId"/>]]></source>
- contains the name of the field-descriptor describing the
- foreignkey fields.
+<foreignkey field-ref="productGroupId"/>]]></source>
+ contains the name of the field-descriptor describing the
foreignkey fields.
The FieldDescriptor with the name "productGroupId"
describes the foreignkey attribute
productGroupId:
<source><![CDATA[
- <field-descriptor
- name="productGroupId"
- column="Kategorie_Nr"
- jdbc-type="INTEGER"
- />]]></source>
- </li>
+<field-descriptor
+ name="productGroupId"
+ column="Kategorie_Nr"
+ jdbc-type="INTEGER"
+/>]]></source>
+ OJB assumes that field used in
field-ref references the <em>primary-key</em> field
+ of the referenced type
"org.apache.ojb.broker.ProductGroup".
+ If field-ref should point to another field use the
<em>target-field-ref</em>:
+ <source><![CDATA[
+<foreignkey field-ref="productGroupName"
target-field-ref="groupName"/>]]></source>
+ An example of a 1:1 relationship using a non-primary-key
field can be
+ found <link href="#non-pk-1:1">here</link>.
+ </li>
</ul>
<p>
See the following extract from the repository.xml file
containing
@@ -205,11 +211,66 @@
>
<foreignkey field-ref="sampleArticleId""/>
</reference-descriptor>]]></source>
+
<note>
When using primitive primary key fields, please pay
attention on
<link href="site:faq/primitive-null">how OJB manage
<code>null</code> for primitive PK/FK</link>
</note>
+ <anchor id="non-pk-1:1"/>
+ <section>
+ <title>1:1 using non-primary-key field</title>
+ <p>
+ This example shows a relationship based on the field
"productGroupName" referencing a non-primary-key-field.
+ This field of the class
"org.apache.ojb.broker.NoPkReferenceTest$Article_2" is pointing to the
+ field "groupName" of the referenced class.
+ </p>
+ <source><![CDATA[
+<class-descriptor
+ class="org.apache.ojb.broker.NoPkReferenceTest$Article_2"
+ table="Artikel_2" >
+ <field-descriptor
+ name="articleId"
+ column="Artikel_Nr"
+ jdbc-type="INTEGER"
+ primarykey="true"
+ autoincrement="true"
+ />
+ ...
+ <field-descriptor
+ name="productGroupName"
+ column="KatName"
+ jdbc-type="VARCHAR"
+ />
+ ...
+ <reference-descriptor
+ name="productGroup"
+ class-ref="org.apache.ojb.broker.NoPkReferenceTest$ProductGroup_2"
+ >
+ <foreignkey field-ref="productGroupName" target-field-ref="groupName"/>
+ </reference-descriptor>
+</class-descriptor>
+
+<class-descriptor
+ class="org.apache.ojb.broker.NoPkReferenceTest$ProductGroup_2"
+ table="Kategorien_2" >
+ <field-descriptor
+ name="groupId"
+ column="Kategorie_Nr"
+ jdbc-type="INTEGER"
+ primarykey="true"
+ autoincrement="true"
+ />
+ <field-descriptor
+ name="groupName"
+ column="Kategorie_Name"
+ jdbc-type="VARCHAR"
+ />
+ ...
+</class-descriptor>]]></source>
+
+ </section>
+
<section>
<title>1:1 auto-xxx setting</title>
<p>
@@ -334,7 +395,7 @@
<p>
To declare the foreign key mechanics of this collection
attribute
we must add a CollectionDescriptor to the ClassDescriptor of
the
- ProductGoup class. This descriptor contains the following
+ ProductGroup class. This descriptor contains the following
information:
</p>
<ol>
@@ -350,10 +411,18 @@
<li>
The name of field-descriptor of the element class
used as foreign key attributes are defined in
inverse-foreignkey elements:
- <source><![CDATA[
+ <source><![CDATA[
<inverse-foreignkey field-ref="productGroupId"/>]]></source>
This is again pointing to the field-descriptor for the
attribute
<code>productGoupId</code> in class Article.
+
+ OJB assumes that field used in
field-ref references the <em>primary-key</em> field
+ of the referenced type
"org.apache.ojb.broker.Article".
+ If field-ref should point to another field use the
<em>target-field-ref</em>:
+ <source><![CDATA[
+<inverse-foreignkey field-ref="productGroupName"
target-field-ref="groupName"/>]]></source>
+ An example of a 1:n relationship using a non-primary-key
field can be
+ found <link href="#non-pk-1:n">here</link>.
</li>
<li>
optional attributes to define the sort order of the
retrieved collection:
@@ -364,7 +433,7 @@
the ProductGoup ClassDescriptor:</p>
<source><![CDATA[
<!-- Definitions for org.apache.ojb.broker.ProductGroup -->
- <class-descriptor
+<class-descriptor
class="org.apache.ojb.broker.ProductGroup"
table="Kategorien"
>
@@ -393,7 +462,8 @@
>
<inverse-foreignkey field-ref="productGroupId"/>
</collection-descriptor>
- </class-descriptor>]]></source>
+</class-descriptor>]]></source>
+
<p>
With the mapping shown above OJB has two possibilities to
load the Articles belonging
to a ProductGroup:
@@ -447,6 +517,66 @@
<link href="site:faq/primitive-null">how OJB manage
<code>null</code> for primitive PK/FK</link>
</note>
+ <anchor id="non-pk-1:n"/>
+ <section>
+ <title>1:n using non-primary-key field</title>
+ <p>
+ This example shows a relationship based on the field
"productGroupName" referencing a non-primary-key-field.
+ This field of the class
"org.apache.ojb.broker.NoPkReferenceTest$Article_2" is pointing to the
+ field "groupName" of the referenced class.
+ </p>
+ <source><![CDATA[
+<class-descriptor
+ class="org.apache.ojb.broker.NoPkReferenceTest$Article_2"
+ table="Artikel_2" >
+ <field-descriptor
+ name="articleId"
+ column="Artikel_Nr"
+ jdbc-type="INTEGER"
+ primarykey="true"
+ autoincrement="true"
+ />
+ ...
+ <field-descriptor
+ name="productGroupName"
+ column="KatName"
+ jdbc-type="VARCHAR"
+ />
+ ...
+</class-descriptor>
+
+<class-descriptor
+ class="org.apache.ojb.broker.NoPkReferenceTest$ProductGroup_2"
+ table="Kategorien_2" >
+ <field-descriptor
+ name="groupId"
+ column="Kategorie_Nr"
+ jdbc-type="INTEGER"
+ primarykey="true"
+ autoincrement="true"
+ />
+ <field-descriptor
+ name="groupName"
+ column="Kategorie_Name"
+ jdbc-type="VARCHAR"
+ />
+ <field-descriptor
+ name="description"
+ column="Beschreibung"
+ jdbc-type="VARCHAR"
+ />
+ <collection-descriptor
+ name="allArticlesInGroup"
+ element-class-ref="org.apache.ojb.broker.NoPkReferenceTest$Article_2"
+ auto-retrieve="true"
+ auto-update="true"
+ auto-delete="false"
+ >
+ <inverse-foreignkey field-ref="productGroupName"
target-field-ref="groupName"/>
+ </collection-descriptor>
+</class-descriptor>]]></source>
+ </section>
+
<section>
<title>1:n auto-xxx setting</title>
<p>
@@ -867,7 +997,7 @@
<link href="site:faq/primitive-null">how OJB manage
<code>null</code> for primitive PK/FK</link>
</note>
-
+
<section>
<title>m:n auto-xxx setting</title>
<p>
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