hi atipon,
fyi there has been a discussion about subfields before
http://nagoya.apache.org/eyebrowse/ReadMsg?listName=ojb-dev@;jakarta.apache.o
rg&msgId=432969
hth
jakob
----- Original Message -----
From: "atipon pongpat" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, October 20, 2002 9:15 AM
Subject: Need PersistentField impl suggestion
>
> Hi,
> My company currently uses Toplink for o/r mapping, so I want to write an
ojb mapping without any modification to existing domain object. The problem
arises when I try to map nested object on the same table of parent object.
My first solution is rowreader + field conversion.(Thanks to Thomas Mahler
for his response to my friend, Sumeth Chittaprawat) It works fine but I just
don't want to write a rowreader for every class that has a nested object.
> I decided to extend ojb provided PersistentField impl to supports using
of nested attribute. My repository looks something like this.
> <field-descriptor id="2"
> name="name"
> column="SUPP_NAME"
> jdbc-type="CHAR"
> />
>
> <field-descriptor id="3"
> name="audit.createdBy"
> column="CREATED_BY"
> jdbc-type="CHAR"
> />
> Is there something I have to concern when I create my own PersistentField
impl ? I'm afraid that it cannot be used with odmg or jdo api.
>
>
> Thanks in advance,
> Atipon Pongpat
>
> P.S. This my code. Any comments or suggestions are welcome.
> package testojb;
>
> import java.lang.reflect.Field;
>
> import org.apache.ojb.broker.metadata.MetadataException;
> import org.apache.ojb.broker.metadata.PersistentFieldMaxPerformanceImpl;
> import org.apache.ojb.broker.util.logging.Logger;
> import org.apache.ojb.broker.util.logging.LoggerFactory;
>
> /**
> *
> * This class supports using of nested attribute.
> * @author Atipon Pongpat
> */
> public class PersistentNestedFieldMaxPerformanceImpl
> extends PersistentFieldMaxPerformanceImpl {
>
> private String fieldName;
>
> private Logger logger = LoggerFactory.getLogger(this.getClass());
>
> public PersistentNestedFieldMaxPerformanceImpl(Field f) {
> super(f);
> }
>
> public PersistentNestedFieldMaxPerformanceImpl(Class c, String fieldname)
{
> super(c, fieldname);
> this.fieldName = fieldname;
> }
>
> /**
> * @see
org.apache.ojb.broker.metadata.PersistentFieldMaxPerformanceImpl#getFieldRec
ursive(Class, String)
> */
> protected Field getFieldRecursive(Class c, String fieldname)
> throws NoSuchFieldException {
> //thanks for the original implementation of
PersistentFieldMaxPerformanceImpl
> try {
> Field f = null;
> int index = fieldname.indexOf(".");
> if (index >= 0) {
> String name = fieldname.substring(0, index);
> Field field = c.getDeclaredField(name);
> Class nestedClass = field.getType();
> //
> String nestedName = fieldname.substring(index + 1);
> f = getFieldRecursive(nestedClass, nestedName);
> } else {
> f = c.getDeclaredField(fieldname);
> }
> return f;
> } catch (NoSuchFieldException e) {
> // if field could not be found in the inheritance hierarchy, signal
error
> if (c == Object.class) {
> throw e;
> }
> // if field could not be found in class c try in superclass
> else {
> return getFieldRecursive(c.getSuperclass(), fieldname);
> }
> }
> }
>
> /**
> * @see org.apache.ojb.broker.metadata.PersistentField#get(Object)
> */
> public Object get(Object anObject) throws MetadataException {
> return getNestedObject(anObject, fieldName);
> }
>
> /**
> * @see org.apache.ojb.broker.metadata.PersistentField#set(Object,
Object)
> */
> public void set(Object obj, Object value) throws MetadataException {
> setNestedObject(obj, fieldName, value);
> }
>
>
> /**
> * Set nested attribute with given value.
> * @param obj the object whose field should be modified
> * @param fieldName nested attribute name
> * @param value the new value for the field of obj being modified
> */
> protected void setNestedObject(Object obj, String fieldName, Object
value) {
>
> int index = fieldName.indexOf(".");
> if (index >= 0) {
> String name = fieldName.substring(0, index);
> PersistentFieldMaxPerformanceImpl pField =
> new PersistentFieldMaxPerformanceImpl(obj.getClass(), name);
> Object attrib = pField.get(obj);
>
> if (attrib == null) {
> try {
> attrib = pField.getType().newInstance();
> } catch (InstantiationException e) {
> throw new MetadataException(
> "Error instantiate field:"
> + name
> + " in object:"
> + obj.getClass().getName(),
> e);
> } catch (IllegalAccessException e) {
> throw new MetadataException(
> "Error getting field:"
> + name
> + " in object:"
> + obj.getClass().getName(),
> e);
> }
>
> pField.set(obj, attrib);
> }
> //
> String nestedName = fieldName.substring(index + 1);
>
> setNestedObject(attrib, nestedName, value);
> } else {
>
> PersistentFieldMaxPerformanceImpl pField =
> new PersistentFieldMaxPerformanceImpl(
> obj.getClass(),
> fieldName);
> pField.set(obj, value);
> }
>
> }
>
> /**
> * Get nested attribute with given field name.
> * @param obj object from which the represented field's value is to be
extracted
> * @param fieldName nested attribute name
> * @return Object the value of the represented field in object obj
> */
> protected Object getNestedObject(Object obj, String fieldName) {
>
> Object result = null;
> int index = fieldName.indexOf(".");
> if (index >= 0) {
> String name = fieldName.substring(0, index);
> PersistentFieldMaxPerformanceImpl pField =
> new PersistentFieldMaxPerformanceImpl(obj.getClass(), name);
> Object attrib = pField.get(obj);
>
> if (attrib != null) {
> //
> String nestedName = fieldName.substring(index + 1);
> result = getNestedObject(attrib, nestedName);
> }
> } else {
>
> PersistentFieldMaxPerformanceImpl pField =
> new PersistentFieldMaxPerformanceImpl(
> obj.getClass(),
> fieldName);
> result = pField.get(obj);
> }
>
> return result;
> }
>
> }
>
>
>
>
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