org.dbunit.dataset.NoPrimaryKeyException: COHORT_MEMBER

In the Cohort mapping file the cohort_member table is mapped like any hibernate collection:

<set name="memberIds" cascade="none" lazy="true" table="cohort_member">
    <key column="cohort_id" />
    <element column="patient_id" type="integer" />
</set>

It looks normal enough.  Cohort.memberIds is a list of integers defined by the cohort_member table.

Hibernate automatically creates the schema in our test hsqldb because we have hbm2ddl set to “auto”.  The problem arose here because hibernate wasn’t creating a dual primary key on the member_ids table.  Digging through the code, I found that Hibernate only assumes the primary keys are the columns that set to “not null”.

The corrected mapping with both columns set to be not-null:

<set name="memberIds" cascade="none" lazy="true" table="cohort_member">
    <key column="cohort_id" not-null="true"/>
    <element column="patient_id" type="integer" not-null="true"/>
</set>

Now hibernate creates the table with primary keys and hsql is happy again.