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Posted to ojb-dev@db.apache.org by ar...@apache.org on 2004/04/05 19:21:24 UTC
cvs commit: db-ojb/xdocs tutorial3.xml
arminw 2004/04/05 10:21:24
Modified: xdocs tutorial3.xml
Log:
- add note in m:n relation section NOT to use a removal aware collection
Revision Changes Path
1.35 +23 -5 db-ojb/xdocs/tutorial3.xml
Index: tutorial3.xml
===================================================================
RCS file: /home/cvs/db-ojb/xdocs/tutorial3.xml,v
retrieving revision 1.34
retrieving revision 1.35
diff -u -r1.34 -r1.35
--- tutorial3.xml 5 Apr 2004 13:59:01 -0000 1.34
+++ tutorial3.xml 5 Apr 2004 17:21:24 -0000 1.35
@@ -598,7 +598,7 @@
<b>none</b> On updating or inserting of the main object with <code>PersistenceBroker.store(...)</code>,
the referenced objects are NOT updated by default. The referenced objects will not be <i>inserted</i> or
<i>updated</i>, the referenced objects will not be linked (foreign key assignment on referenced objects)
- to the main object automatically.
+ to the main object automatically.
The user has to link and to store the referenced objects <i>after</i> storing the main object
to avoid violation of referential integrity.
</li>
@@ -627,7 +627,7 @@
<li>
<b>none</b>
On deleting an object with <code>PersistenceBroker.delete(...)</code> the referenced objects are
- NOT touched. This may lead to violation of referential integrity if the referenced objects
+ NOT touched. This may lead to violation of referential integrity if the referenced objects
are childs of the main object. In this case the referenced objects have to be deleted manually first.
</li>
<li>
@@ -863,6 +863,24 @@
table:
</p>
+ <p>
+ <strong>NOTE:</strong> OJB supports a multiplicity of collection implementations,
+ inter alia <code>org.apache.ojb.broker.util.collections.RemovalAwareCollection</code>
+ and <code>org.apache.ojb.broker.util.collections.RemovalAwareList</code>. By default the
+ removal aware collection was used. This cause problems in m:n relations when
+ <code>auto-update="true"</code> and <code>auto-delete="false"</code> is set, because objects
+ deleted in the collection will be deleted on update of main object. Thus it is recommended to
+ use a NOT removal aware collection class in m:n relations by setting e.g.
+ </p>
+ <source>
+collection-class="org.apache.ojb.broker.util.collections.ManageableArrayList"
+ </source>
+ <p>
+ in the collection-descriptor.
+ </p>
+ <p>
+ An example for a m:n relation looks like:
+ </p>
<source><![CDATA[
<class-descriptor
class="org.apache.ojb.broker.Person"
@@ -970,7 +988,7 @@
the referenced objects are NOT updated by default. The referenced objects will not be <i>inserted</i> or
<i>updated</i>, but the m:n relation will be linked automatically (creation of FK entries in the indirection table).
<br/>
- NOTE: Make sure that the referenced objects exist in database before storing the main object
+ NOTE: Make sure that the referenced objects exist in database before storing the main object
to avoid violation of referential integrity.
</li>
<li>
@@ -1124,7 +1142,7 @@
<p>If in <code>reference-descriptor</code> or <code>collection-descriptor</code> the <i>auto-update</i> or
<i>auto-delete</i> attributes are set to <i>none</i>, OJB does not touch the referenced objects on insert,
update or delete operations of the main object. The user has to take care of the correct handling of
- referenced objects.
+ referenced objects.
When using referential integrity (who does not ?) it's essential that insert and delete operations are done
in the correct sequence.
</p>
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