Is it possible to map cyclical references using hibernate? This is currently my main road block for scrapping my home grown O/R mapping in favor of hibernate.

In particular my class looks like this....

public class KeyValuePair
{
private int id;
private int parentId;
private KeyValuePair[] categories = new KeyValuePair[ 0 ];

.....
}

I have a mapping file, but it fails to create the table for this class. Is this possible?

~harris

yes it is possible you can have to-one and to-many relationship between the same class

I have that in my map file....

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="KeyValuePair" table="taxonomyvalues">
<id name="id" type="integer" column="taxonomy_id" >
<generator class="hilo"/>
</id>
<property name="parentId" column="parentId" type="integer"/>
<property name="taxonomyKey" column="taxonomy_key" type="string"/>
<property name="key" column="key" type="string"/>
<property name="value" column="value" type="string"/>
<property name="enabled" column="enabled" type="boolean"/>
<array name="categories" table="taxonomyvalues" inverse="false" cascade="none">
<key column="taxonomy_id" foreign-key="taxonomy_key"/>
<index column="categories_index"/>
<one-to-many class="KeyValuePair"/>
</array>
</class>
</hibernate-mapping>


... but I get this when running Schema export....


create table taxonomyvalues (taxonomy_id INTEGER not null, parentId INTEGER, taxonomy_key VARCHAR(255), key VARCHAR(255), value VARCHAR(255), enabled BIT, categories_index INTEGER, primary key (taxonomy_id))
10:30:17,732 DEBUG SchemaExport:149 - create table taxonomyvalues (taxonomy_id INTEGER not null, parentId INTEGER, taxonomy_key VARCHAR(255), key VARCHAR(255), value VARCHAR(255), enabled BIT, categories_index INTEGER, primary key (taxonomy_id))
10:30:17,732 ERROR SchemaExport:154 - Unsuccessful: create table taxonomyvalues (taxonomy_id INTEGER not null, parentId INTEGER, taxonomy_key VARCHAR(255), key VARCHAR(255), value VARCHAR(255), enabled BIT, categories_index INTEGER, primary key (taxonomy_id))
10:30:17,732 ERROR SchemaExport:155 - Syntax error or access violation, message from server: "You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'VARCHAR(255), value VARCHAR(255), enabled BIT, categories_index"


Gotta hate that! :-)

~harris

it's just a schema creation problem not a hibernate problem, are you sure you are using the good dialect?

show hibernate.cfd.xml

I'm not familiar with hibernate.cfd.xml [1]. Here is the config info from hibernate.properties....

# $Id: //kenobi/src/java/hibernate.properties#5 $
# $DateTime: 2004/04/20 13:00:57 $
# $Revision: #5 $

hibernate.dialect net.sf.hibernate.dialect.MySQLDialect
#hibernate.dialect net.sf.hibernate.dialect.OracleDialect
#hibernate.dialect com.dante.util.OptimizeOracleDialect

hibernate.connection.driver_class com.mysql.jdbc.Driver
hibernate.connection.url jdbc:mysql://localhost/test

....

hibernate.query.substitutions true 1, false 0, yes 'Y', no 'N'
hibernate.query.imports net.sf.hibernate.test, net.sf.hibernate.eg
hibernate.use_outer_join false
hibernate.jdbc.use_scrollable_resultset false
hibernate.jdbc.use_streams_for_binary true
hibernate.show_sql false

## set the maximum JDBC 2 batch size (a nonzero value enables batching)
hibernate.jdbc.batch_size 0

thanks,

~harris

[1] http://www.google.com/search?hl=en&ie=U ... gle+Search

Maybe I could get similiar behavior by using a TreeMap for the hierarchical data instead of a cyclical reference. Does hibernate support mapping a tree structure?

thanks a bunch for the tips,

~harris

you're going to change your structure just because schema export throw an error?
do what you want

I'd rather not change the structure, but I need to do whatever works. Is there a dialect for MySQL that I am missing that would help with the SchemaExport?

~harris

let's wait for an expert of schema export or mySQL.... be patient

"key" is a keyword on mysql. Rename the column in the mapping.

mickeal = mySql ShemaExport Hero !

Did I mention already that I hate mysql :)

michael & anthony = my hibernate heros;

thanks,

~harris

i've done nothing... just advised you to be patient ;)