Andreas,
Out of curiosity, how would one go about storing an array of values in a varchar field
anyhow ?
Werner
On Fri, 5 Nov 2004 08:47:00 -0500, Nick Stuart wrote:
>
>Andreas, I misunderstood your first post. This type of setup will not
>work unfortunately. When storing collections/arrays they need to be
>stored if a separate table and be linked by some kind of key back to
>the parent object.
>
>For now there is no way to store an array of objects directly in a
>field of a database.
>
>-Nick
>
>
>On Fri, 05 Nov 2004 14:38:18 +0100, Andreas Vombach
><[EMAIL PROTECTED]> wrote:
>>
>> Hi Werner,
>>
>> thank you very much for your reply. No, it shall be only one one table like
>>
>> create table test (ID integer PRIMARY KEY NOT NULL, MYARRAY varchar(255));
>>
>> As said it works for the first element to be inserted and the MYARRAY
>> column looks like [Ljava.lang.String;@f42ad0 in the db
>> which appears to be the serialized form of new String[] {"1", "2", "3",
>> "4", "5"} and it is retrievable after insert.
>> Inserting a second row causes the exception on retrieve. Here the test
>> program: (the "mydb.xml" is as usual, engine is MySQL in my case)
>>
>> import java.util.*;
>> import org.exolab.castor.jdo.*;
>> import org.exolab.castor.mapping.*;
>>
>> public class jdotest
>> {
>> static JDO jdo;
>> static Database db;
>>
>> public static void main (String[] args)
>> {
>> jdo = new JDO("mydb");
>> try
>> {
>> jdo.loadConfiguration("mydb.xml");
>> }
>> catch (Exception ex)
>> {
>> System.out.println("JDO load Exception: " + ex);
>> }
>> try
>> {
>> db = jdo.getDatabase();
>> test t = new test();
>> t.setId(new Integer(1));
>> t.setMyarray(new String[] {"1", "2", "3", "4", "5"});
>> db.create(t);
>> db.commit();
>> db.close();
>> System.out.println("store ok, id: " + t.getId());
>> db = jdo.getDatabase();
>> db.begin();
>> OQLQuery query = db.getOQLQuery("SELECT a FROM test a WHERE id=$1");
>> query.bind(new Integer(1));
>> QueryResults results = query.execute(Database.ReadOnly);
>> test res = (test) results.next();
>> System.out.println("test retrieved");
>> System.out.println("id: " + res.getId());
>> String[] s = res.getMyarray();
>> for (int i = 0; i < s.length; i++) System.out.println("myarray:
>> " + s[i]);
>> }
>> catch (Exception ex)
>> {
>> System.out.println("JDO queryException: " + ex);
>> ex.printStackTrace();
>> }
>> try
>> {
>> db.close();
>> }
>> catch (PersistenceException ex) {}
>>
>>
>> }
>> }
>>
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>
>
>
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