I'm new to Hibernate and I'm trying to get some basic unit tests working. I am getting a "not-null property references a null or transient value" error message.

I have two domain objects: Pet and Category. Pet can belong to at most one category. I have two corresponding DAO's: PetDao and CategoryDao.

In PetDaoTest I create a transient Category and call setCategory on the Pet object. Then I'm trying to save the Pet object. I think Hibernate is complaining b/c there is no FK for the Category object since its not persistent and there is no cascade from the category property. (Please confirm.)

So my question is more of a design question. How can I have an effective unit test that isolates the PetDao without involving CategoryDao? Does it make sense to have the two separate DAO's at all? If so, does it make sense to test them separately?

Regards,

Sean


<class name="Pet">
<id name="id"
column="pet_id"
type="long"
unsaved-value="0">
<generator class="native"/>
</id>
<property name="description"/>
<property name="price"/>
<property name="quantity"/>
<many-to-one
name="category"
column="category_id"
class="Category"
not-null="true"/>
</class>

<class name="Category">
<id name="id"
column="CATEGORY_ID"
type="long"
unsaved-value="0">
<generator class="native"/>
</id>
<property name="description"/>
<property name="parentCategory"/>
<set name="pets"
inverse="true"
cascade="save-update">
<key column="category_id"/>
<one-to-many class="Pet"/>
</set>
</class>

Hibernate is complaining because it must have a category ID to save into the category_id column of the pet table, but you have no ID to save.

To work around this without using CategoryDAO, have a precondition for you tests be that there must be a row in the category table with ID = 1, and that any category object you create for unit testing purposes must have ID 1. Hibernate will match your transient category object with the dummy unit test category row, and all will be well.