Note: I am using Hibernate version 2.1.1, PostgreSQL version 7.4.1

Hi,
I have a user map for which, as well as generating a primary key, need to make sure that the username and userpassword are unique as well to ensure that no 2 records with the same username, userpassword combination exist.

In the map shown below, I tried to add a composite-key section but am getting errors. How do I resolve this issue???

My map is:

<hibernate-mapping package="test">
<class name="User" table="usertbl">
<id name="ID" column="user_id" type="integer" unsaved-value="0">
<generator class="sequence">
<param name="sequence">seq_user_mytable</param>
</generator>
</id>
...... Other property definitions ...............
<composite-id name="CompID" class="User">
<key-property name="UserName" column="username" type="string"/>
<key-property name="UserPassword" column="userpassword" type="string"/>
</composite-id>

<set name="ArtistChoice" table="choicetbl">
<key column="user_id"/>
<many-to-many column="artist_id" class="test.Artist"/>
</set>
</class>
</hibernate-mapping>

Don't make the username and password part of an id. (There can only be one id per class...) Assign a unique constraint to the properties:


This ensures that no two usernames exist that are the same.

If you want the combination of two properties to be unique, you can create multi column indices like so:

thanks for your quick reply. I have amended my map with the following lines:

<property name="UserName" type="string">
<column name="username" unique-key="UserPassKey"/>
</property>
<property name="UserPassword" type="string">
<column name="userpassword" unique-key="UserPassKey"/>
</property>

This still allows me to enter duplicate records with the same username password comnbination. What am I doing wrong or have forgotten to do??

Peter

Simply defining a property as unique in the mapping file, in and of itself, is not going to do anything. If you ran the mapping file through the schema generator tool, it would generate unique constraints for you on the corresponding database columns.

If you have are not using Hibernate's schema generation, simply alter those columns to have a unique constraint on them directly in the database.