Hi,
I'm designing a java class which is mostly persisted in the database but
that also has a field that need to be 'persisted' using java code. I was
wondering if 'transient="true"' in mapping.xml is the right thing for this
type of field... According to docs "transient" fields neither persist nor
marshal; I want it to marshal / unmarshal, but not persist in DB. I *did*
make it work using 'transient="true"' the way I want it to, but I had to
modify SQLEngine.java and was wondering if it was the right thing to do...
Here is the portion of mapping.xml for my class:
<class name="com.acme.File" identity="id" key-generator="oracle">
<map-to table="docfile" xml="file" />
<field name="id" type="integer">
<sql type="numeric" name="docfile_id" />
<bind-xml node="attribute" name="id" />
</field>
<field name="name" type="string">
<sql type="char" name="docfile_name" />
<bind-xml node="element" name="name" />
</field>
...
<field name="content" type="bytes" transient="true" required="false">
<bind-xml type="xsd:base64Binary" node="element" name="content" />
</field>
</class>
The File class was originally generated using SourceGenerator, using XSD
that looks like this:
<xsd:element name="file">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="name" type="xsd:string" maxOccurs="1" />
<xsd:element name="location" type="xsd:string" maxOccurs="1" />
<xsd:element name="content" type="xsd:base64Binary" minOccurs="0"
maxOccurs="1" />
</xsd:sequence>
<xsd:attribute name="id" type="xsd:integer" minOccurs="1"
maxOccurs="1" />
</xsd:complexType>
</xsd:element>
Now I also wrote event / listner classes that implement CallbackInterceptor
to intercept 'loading' event, so when com.acme.File object is loaded w/
SELECT statement, I can fill the "content" field with the java code (in this
case, I read files from local filesystem). After that castor seems to take
care of marshaling the object to XML very nicely. However in order for that
to work, I first had to fix SQLEngine.java so it doesn't cause
ClassCastException. Apparently, around line1444 it tries and fails to cast
XMLFieldDescriptor to JDOFieldDescriptor, and I had to modify it so that it
doesn't add SQL columns for the "transient" field:
[org.exolab.castor.jdo.engine: 1440]
// primitive field
boolean isJDO = fieldDesc instanceof JDOFieldDescriptor;
this.tableName = classTable;
this.jdoName = fieldDesc.getFieldName();
this.load = true;
this.multi = false;
this.joined = false;
this.joinFields = null;
this.store = !ext && isJDO &&
!((JDOFieldDescriptor)fieldDesc).isReadonly();
this.dirtyCheck = isJDO &&
((JDOFieldDescriptor)fieldDesc).isDirtyCheck();
FieldHandlerImpl fh = (FieldHandlerImpl)
fieldDesc.getHandler();
if(!isJDO)
this.columns = new ColumnInfo[0];
else {
this.columns = new ColumnInfo[1];
String[] sqlNameArray =
((JDOFieldDescriptor)fieldDesc).getSQLName();
String sqlName;
if ( sqlNameArray == null ) {
sqlName = fieldDesc.getFieldName();
} else {
sqlName = sqlNameArray[0];
}
this.columns[0] = new ColumnInfo( sqlName,
((JDOFieldDescriptor)fieldDesc).getSQLType()[0],
fh.getConvertTo(),
fh.getConvertFrom(), fh.getConvertParam() );
}
With this change apparently my code works fine. My question is, is this a
valid fix? Would this cause problems for other things (since I really don't
know what's going on with other parts of castor :-p)? Or is there some other
parameter I should've specified in mapping.xml, etc. for it to work without
modifying SQLEnginge.java?
Thanks,
Tomoki
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