I am having trouble implementing a map in Hibernate. I have checked out the message board, but have not found a close enough match for what I am trying to do. I am working from an existing Oracle DB, so I can not use Hibernate to derive the DDL. Here is my setup:

3 Java Classes
-------------------

UsersTO
- private long sequenceId;
- private String userName;
- private PreferencesTO preferences;

PreferencesTO
- private Map panelsettings;
- private String defaultViewName;

PanelSettingsTO
- private boolean minimized;


4 Tables
-------------------
u_users
- u_id NUMBER(6);
- user_name VARCHAR2(18);

u_preferences
- u_id NUMBER(6);
- default_view_name VARCHAR2(24);

u_panel_settings
- u_id NUMBER(6);
- panel_id NUMBER(4);
- minimized CHAR(1);
- primary key = u_id & panel_id

u_panels
- panel_id NUMBER(6);
- panel_name VARCHAR(17);


hbm.xml
---------------------------
<class name="UserTO" table="u_users"
<id name="sequenceId" column="u_id" type="long" unsaved-value="0">
<generator class="sequence">
<param name="sequence">UID_SEQ</param>
</generator>
</id>
<property name="userName" column="user_name" type="string"/>
<one-to-one name="peferences" class="PeferencesTO" cascade="all"/>
</class>

<class name="PreferencesTO" table="u_preferences"
<id column="u_id" type="long" unsaved-value="0">
<generator class="foreign"></generator>
</id>
<property name="defaultViewName" column="default_view_name" type="string"/>
<map name="panelSettings">
<key column="u_id">
<index column="panel_id" type="long"/>
<composite-element class="PanelSettingsTO"/>
</map>
</class>

<class name="PanelSettingsTO" table="u_panel_settings"
<composite id>
<key-property column="u_id">
<key-property column="panel_id">
</composite id>
<property name="minimized" column="minimized" type="yes_no"/>
</class>


I am unsure of a couple of aspects of the hibernate mapping that I have shown above:

1. The <map> tag.
2. The way that I used the <composite-id> tag in PanelSettingsTO

I when I run the application I get a message saying "ClassNotFound- org/omgd/DMap" . I think this is the first of many errors... I looked in my hibernate jar file, and I do have the Map class definition.

Thank you for any help that you can provide,
Charles

Add odmg.jar in your CP.

Thank you Emmanuel,

Momentary lapse of reason. I was so unsure of the composite-id and <map> stuff, I didn't think to use a little common sense. I appreciate the help and am making progress with the composite-id and mapping stuff.

Thanks,
Charles

I recommend you not to make too much progress on composite-id. Prefer surrogate keys rather than business ones. Hibernate mapping will be far more easier, and your DB design will be far more stable (surrogate keys don't change their mind, users/techies do).

Emmanuel,

Point well taken.... but the DB came before the current app and I don't have the power to change it!

I am close on the mapping I want to do, but not quite there. Here is what I have so far:


3 Java Classes
-------------------

UsersTO
- private long sequenceId;
- private String userName;
- private PreferencesTO preferences;

PreferencesTO
- private Map panelsettings;
- private String defaultViewName;

PanelSettingsTO
- private boolean minimized;


4 Tables
-------------------
u_users
- u_id NUMBER(6);
- user_name VARCHAR2(18);

u_preferences
- u_id NUMBER(6);
- default_view_name VARCHAR2(24);

u_panel_settings
- u_id NUMBER(6);
- panel_id NUMBER(4);
- minimized CHAR(1);
- primary key = u_id & panel_id

u_panels
- panel_id NUMBER(6);
- panel_name VARCHAR(17);


hbm.xml
---------------------------



The code/mappings above allow me to use the panel_id as a key into the the panelSettings Map. What I would like to do, actually what the app developer wants to do ;), is to use panel_name as the key. The problem is that panel_name is in another table (U_PANELS). In straight SQL, the answer is easy, just join U_PANEL_SETTINGS and U_PANELS on PANEL_ID, but I have not been able to do so with the hibernate mapping. I can get very close. I can either create the java.util.Map with panel_id as the key, or I can get hibernate to try and use panel_name but I get an error because it is trying to find the field in U_PANEL_SETTINGS. The question, is it possible to use a value from another table as the key into a <map>?

Thanks again,
Charles