hi atipon, thomas,
does this solution interfere with path expressions and joins ?
given you have an attribute named 'audit.createdBy' in a selection criteria.
when building the sql, ojb will try to find a relationship called 'audit'
because of the dot-notation.
this problem coud eventually be solved by using another notation
(audit#createdBy, audit->createdBy).
just my CHF 0.02
jakob
----- Original Message -----
From: "Thomas Mahler" <[EMAIL PROTECTED]>
To: "OJB Users List" <[EMAIL PROTECTED]>
Sent: Sunday, October 20, 2002 12:12 PM
Subject: Re: Need PersistentField impl suggestion
> Hi Atipon,
>
> atipon pongpat wrote:
> > 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.
>
> Hey, this is a cool idea! I've never thought of this solution.
> I think we should integrate it into the main distribution. As it will
> solve a lot of problems.
>
> > <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 ?
>
> No, no problems to be expected.
>
> > I'm afraid that it cannot be
> > used with odmg or jdo api.
>
> I don't see any problems.
>
> cheers,
> Thomas
>
> >
> > 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#getF-
> > ieldRecursive(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; }
> >
> > }
> >
> >
> >
> >
> > --------------------------------- Do you Yahoo!? Y! Web Hosting - Let
> > the expert host your web site
>
>
>
>
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