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Posted to ojb-user@db.apache.org by 蔡博至 <Do...@dsc.com.tw> on 2003/06/12 08:51:00 UTC
Problem of dynamic proxy?
Hi!
I declare a class-descriptor of A. Its proxy property is set dynamic. I try to load it from DB by oql command. The return collection is DList(because the OqlCollectionClass=org.apache.ojb.odmg.collections.DListImpl is set in OJB.properties), but the elements in DList are proxy objects not A. How can I get A from DList except that I must not set A proxy property dynamic?
A class descript:
<class-descriptor class="A" table="A" proxy="dynamic">
:
:
:
</class-descriptor>
oql command : "select o from A"
Using ODMG:
1 String pQueryString = "select o from A";
2 DList tResult = null;
3 try {
4 Transaction tx = this.odmg.currentTransaction();
5 OQLQuery tQuery = this.odmg.newOQLQuery();
6 tQuery.create(pQueryString);
7 tResult = (DList)tQuery.execute();
8 } catch (Exception e) {
9 e.printStackTrace();
10 throw new DBServerException(e.getMessage());
11 }
12 Iterator tIter = tResult.iterator();
13 while (tIter.hasNext()){
14 Ａ tA = (A)tIter.next();
:
:
}
I got a error message :"java.lang.ClassCastException: $Proxy119" on line 14.
Re: Problem of dynamic proxy?
Posted by Marcus Breese <ma...@breese.com>.
Are there any other requirements of this? Because I have a similar
situation, and there isn't any sample code on the website.
I'm trying to use Dynamic proxies, My tables are setup as such:
TableName (derived object for business rules), implements
TableNameInterface
|
|-- TableNameCO ( derived object for collections to be placed in ) ,
implements TableNameCOInterface
|
|-- TableNameBO (base object - all table fields go here) , implements
TableNameBOInterface
|
|-- BaseObject (super object - contains a custom toString that
dynamically prints this object's contents)
TableNameInterface extends TableNameCOInterface
TableNameCOInterface extends TableNameBOInterface
TableNameBOInterface includes all getColumn and setColumn definitions.
Now, I'm attempting to load an object by criteria,
<code>
Criteria crit = new Criteria();
crit.addEqualTo("username",u);
crit.addEqualTo("password",new MD5(p));
Query q = QueryFactory.newQuery(AclUser.class,crit);
AclUserInterface IUser=null;
try {
/* WORKS */
Object obj = broker.getObjectByQuery(q);
/* Throws ClassCastException */
IUser = (AclUserInterface) broker.getObjectByQuery(q);
} catch { .... }
</code>
Now, if I do a System.out.println(obj), I get the full object record as
it should be... complete with the collections (thanks to my toString()
in BaseObject).
But the IUser conversion dies.
Am I just an idiot? I've been playing with this for 2 days and have no
clue... any assistance would be appreciated. I think that there should
be some sample code for this included in the Tutorial, as this is
probably a feature that people will want to use.
===============================
Here are the appropriate snippets from my repository file (for table
AclUser)
<class-descriptor
class="edu.iupui.cmg.labratj.om.AclUserCO"
proxy="dynamic"
>
<extent-class class-ref="edu.iupui.cmg.labratj.om.AclUser"/>
</class-descriptor>
<class-descriptor
class="edu.iupui.cmg.labratj.om.AclUserBO"
>
<extent-class class-ref="edu.iupui.cmg.labratj.om.AclUserCO"/>
</class-descriptor>
<class-descriptor
class="edu.iupui.cmg.labratj.om.AclUser"
proxy="dynamic"
table="acl_user"
>
<field-descriptor
name="id"
column="id"
jdbc-type="INTEGER"
primarykey="true"
nullable="false"
autoincrement="true"
>
</field-descriptor>
<field-descriptor
name="username"
column="username"
jdbc-type="VARCHAR"
nullable="false"
>
</field-descriptor>
<field-descriptor
name="password"
column="password"
jdbc-type="VARCHAR"
nullable="false"
>
</field-descriptor>
<field-descriptor
name="first"
column="first"
jdbc-type="VARCHAR"
nullable="false"
>
</field-descriptor>
<field-descriptor
name="last"
column="last"
jdbc-type="VARCHAR"
nullable="false"
>
</field-descriptor>
<field-descriptor
name="email"
column="email"
jdbc-type="VARCHAR"
nullable="false"
>
</field-descriptor>
</class-descriptor>
On Thursday, June 12, 2003, at 02:18 PM, vinicius.bomfim@globo.com
wrote:
>
> You have to create an interface and your class implement that
> interface.
>
> And then you have to cast whith that interface.
>
> IA tA = (A)tIter.next();
>
> Vinicius Bomfim
>
-=-= -=-= -=-= -=-= -=-= -=-= -=-= -=-= -=-= -=-= -=-=-
Marcus Breese mbreese@iupui.edu
IU School of Medicine marcus@breese.com
Dept. of Biochemistry and Molecular Biology
Center for Medical Genomics / Grow Lab
RE: Problem of dynamic proxy?
Posted by vi...@globo.com.
Hi,
You have to create an interface and your class implement that interface.
And then you have to cast whith that interface.
IA tA = (A)tIter.next();
Vinicius Bomfim
'>'-- Mensagem Original --
'>'Reply-To: "OJB Users List" <oj...@db.apache.org>
'>'Reply-To: ??? <Do...@dsc.com.tw>
'>'From: ??? <Do...@dsc.com.tw>
'>'To: "OJB Users List" <oj...@db.apache.org>
'>'Subject: Problem of dynamic proxy?
'>'Date: Thu, 12 Jun 2003 14:51:00 +0800
'>'
'>'
'>'Hi!
'>' I declare a class-descriptor of A. Its proxy property is set dynamic.
'>'I try to load it from DB by oql command. The return collection is DList(because
'>'the OqlCollectionClass=org.apache.ojb.odmg.collections.DListImpl is
set in
'>'OJB.properties), but the elements in DList are proxy objects not A.
How can
'>'I get A from DList except that I must not set A proxy property dynamic?
'>'
'>'A class descript:
'>' <class-descriptor class="A" table="A" proxy="dynamic">
'>' :
'>' :
'>' :
'>' </class-descriptor>
'>'
'>'oql command : "select o from A"
'>'
'>'Using ODMG:
'>'
'>'1 String pQueryString = "select o from A";
'>'2 DList tResult = null;
'>'3 try {
'>'4 Transaction tx = this.odmg.currentTransaction();
'>'5 OQLQuery tQuery = this.odmg.newOQLQuery();
'>'6 tQuery.create(pQueryString);
'>'7 tResult = (DList)tQuery.execute();
'>'8 } catch (Exception e) {
'>'9 e.printStackTrace();
'>'10 throw new DBServerException(e.getMessage());
'>'11 }
'>'12 Iterator tIter = tResult.iterator();
'>'13 while (tIter.hasNext()){
'>'14 ? tA = (A)tIter.next();
'>' :
'>' :
'>' }
'>'
'>'I got a error message :"java.lang.ClassCastException: $Proxy119" on
line
'>'14.