Hi,
I have a many to many relationship in between Group and Customer classes. Also Group and Customer classes having one-to-one relationship with Marchant class.

hbm.xml mapping file as follows.

<class name="Marchant" table="Marchants">
<id name="stringId" column="MarchantId" length="50"/>
<property name="marchantName" column="MarchantName" length="200" not-null="true" />
<property name="email" column="Email" length="100" />
<property name="msisdn" column="Msisdn" length="20" />
<property name="lastModifiedDateTime" column="LastModifiedDateTime" type="timestamp"/>
<property name="status" column="Status" length="10" />
<property name="shortCode" column="ShortCode" length="20" />
</class>

<class name="Customer" table="Customers">
<composite-id name="CustomerCompositeId" >
<key-property name="customerId" type="long" column="CustomerId" length="50" />
<key-many-to-one name="marchant" column="MarchantId" />
</composite-id>
<property name="msisdn" column="MSISDN" length="20" unique="true"/>
<property name="shortName" column="ShortName" length="200"/>
<property name="fullName" column="FullName" length="200"/>
<property name="email" column="Email" length="100" unique="true"/>
<set name="groups" table="CustomerGroups">
<key column="CustomerId"/>
<many-to-many column="GroupId" class="Group"/>
</set>
</class>

<class name="Group" table="Groups">
<composite-id name="GroupCompositeId" >
<key-property name="stringId" column="GroupId" length="50" />
<key-many-to-one name="marchant" column="MarchantId" />
</composite-id>
<property name="groupName" column="GroupName" length="100"/>
<property name="description" column="Description"/>
<property name="lastModifiedDateTime" column="LastModifiedDateTime" type="timestamp"/>
<set name="customers" table="CustomerGroups" inverse="true">
<key column="GroupId"/>
<many-to-many column="CustomerId" class="Customer"/>
</set>
</class>

If I'm going to create database table by giving the above hbm.xml mapping file, it throws following exceptions..

org.hibernate.MappingException: Foreign key (FK22573372E1840434:CustomerGroups [CustomerId])) must have same number of columns as the referenced primary key (Customers [CustomerId,MarchantId])
at org.hibernate.mapping.ForeignKey.alignColumns(ForeignKey.java:86)
at org.hibernate.mapping.ForeignKey.setReferencedTable(ForeignKey.java:51)
at org.hibernate.cfg.Configuration.secondPassCompileForeignKeys(Configuration.java:976)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:921)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:999)

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I think this may be due to some thing wrong with the hbm.xml mapping file.

Can somebody tell me how to solve it?

I really appreciate your help.
Thank you.
thilinaa

In your model, a customer is identified by a customerId and a merchantId. Therefore you must also have two keys in the groups definition:

<set name="groups" table="CustomerGroups">
<key column="CustomerId"/>

===> <key column="MerchantId"/>

<many-to-many column="GroupId" class="Group"/>
</set>

I have solve the problem by changing the hbm.xml mapping file as follows;


I can see the created database tables as follows;



But the problem is CustomerGroups table have 2 colums (MarchantIdCustomer and MarchantIdGroup) refers to same data, because both MarchantIdCustomer and MarchantIdGroup refers to Merchant class. This results duplicate data.

But I want to have a CustomerGroups table with 3 columns (i.e. CustomerId, MarchantId, GroupId) . MarchantId represents both MarchantIdCustomer and MarchantIdGroup columns in the previous table. (Since both reperesents same thing, I want to make it one)

Is this possible with Hibernate. If so.. how can we change the hbm.xml mapping file?

I really tired with searching this. Sorry for the long comment...

Thank you.
thilinaa

In your customer class you can use the marchantId column twice by using a formula element (untested):