Hi all,

I have some trouble in mapping with a <list> in a <one-to-many> condition

I have 2 tables:
lm_group and lm_access_rule

lm_group will have a List of lm_access_rule objects (ie. one-to-many)
I have tried to config the tables in the hbm.xml for several options but still failed to save/add lm_access_rule objects.

common errors I have are the following:
1) org.springframework.orm.hibernate3.HibernateSystemException: a different object with the same identifier value was already associated with the session
2) Column 'idx' cannot be null
3) uncategorized SQLException for SQL [insert into lm_access_rule (groupId, rule) values (?, ?)]; SQL state [HY000]; error code [1364]; Field 'idx' doesn't have a default value; nested exception is java.sql.SQLException: Field 'idx' doesn't have a default value

Attached is the table scripts (mysql) + the hbm.xml for your reference
PS. for sure... hibernate didn't handle the "idx" field when trying to persist a lm_access_rule object to the database and therefore throw the above exception(s)

[Scripts]
CREATE TABLE `lm_group` (
`id` int(10) unsigned NOT NULL auto_increment COMMENT 'id / pk for lm_group',
`groupName` varchar(100) NOT NULL COMMENT 'group name',
`description` varchar(200) default NULL COMMENT 'group description',
`status` varchar(1) NOT NULL default 'A',
PRIMARY KEY (`id`),
UNIQUE KEY `unique_groupName` (`groupName`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1

CREATE TABLE `lm_access_rule` (
`groupId` int(10) unsigned NOT NULL,
`rule` varchar(200) character set big5 NOT NULL,
`idx` int(10) unsigned NOT NULL,
UNIQUE KEY `unique_group_rule` USING BTREE (`groupId`,`rule`,`idx`),
CONSTRAINT `FK_lm_access_rule_1` FOREIGN KEY (`groupId`) REFERENCES `lm_group` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

[hbm.xml]

<class
name="BasicCredentialGroup"
table="lm_group">
<id name="id" type="int">
<generator class="native" />
</id>
<property name="groupName" type="string" length="100" />
<property name="description" type="string" length="200" />
<property name="status" type="string" length="1" />

<!-- a 1-to-many mapping -->
<list name="rules" table="lm_access_rule" >
<key column="groupId" />
<list-index column="idx" />
<one-to-many
class="BasicCredentialAccessRule" />
</list>
</class>

<class
name="BasicCredentialAccessRule"
table="lm_access_rule">
<composite-id>
<key-property name="groupId" type="int" />
<key-property name="idx" type="int" />
</composite-id>
<property name="rule" type="string" length="200" />
</class>


Any help or hints would be highly appreciated, thanks

Jason (kusanagihk)

Hi,

Regarding your first error

1) org.springframework.orm.hibernate3.HibernateSystemException: a different object with the same identifier value was already associated with the session

this error occurs if you try to attach an object to the persistence context with an identifier that is alread attached. I had this case several times recently. Check your code if the object you are trying do persist ist loaded earlier. This can happen without loading it explicitly by traversing the object graph, where the object may be included.

cheers
elch

Hi Try using not-null = "true" in the key field of the list

i.e <key column="" notnull="true"/>

I guess this should work let us know how u solved the problem thanks

Yep it is obvious becoz hibernate didn't handle the list index's column; therefore the value must be null for every lm_access_rule instance; and therefore the "identifier" is "already attached" (assume the first null value is acceptable, but the 2nd null value means a duplicate)

So the problem goes back to ... why hibernate couldn't increment the "idx" field.

Um I have tried the "not-null" option; but similar errors giving the same problem again --> hibernate failed to increment the "idx" field



Sort of confusing....

Can you provide the class where you are trying to set the values for the classes and how you are saving the values..also try removing the not-null=true you have in the BasicCredentials class i.e for

<property name="idx" not-null="true"> remove that

The code for the classes are below:



I think the classes are just the simplest POJO; therefore, it should be the settings in the hbm.xml I have missed out.