I've been struggling trying to get an m:n relationship set up. It is
a simple variation on the tutorial. I have added a
PRODUCT_CATEGORY_NAME table and I relate this to a PRODUCT through a
PRODUCT_CATEGORY table.
I've been chasing this for quite a while, and I've searched through
the archives, but I can't seem to figure out how to express this both
in the schema and the repository files.
the schema looks like this:
<table name="PRODUCT">
<column name="ID" required="true" primaryKey="true"
type="INTEGER"/>
<column name="NAME" type="VARCHAR" size="100"/>
<column name="PRICE" type="FLOAT"/>
<column name="DISCOUNT" type="FLOAT"/>
<column name="STOCK" type="INTEGER"/>
</table>
<table name="PRODUCT_CATEGORY_NAME">
<column name="ID" required="true" primaryKey="true"
type="INTEGER"/>
<column name="NAME" type="VARCHAR" size="48"
primaryKey="true"/>
<unique>
<unique-column name="NAME"/>
</unique>
</table>
<table name="PRODUCT_CATEGORY">
<column name="PRODUCT_ID" required="true" primaryKey="true"
type="INTEGER"/>
<column name="PRODUCT_CATEGORY_NAME_ID" required="true"
primaryKey="true" type="INTEGER"/>
<foreign-key foreignTable="PRODUCT">
<reference local="PRODUCT_ID" foreign="ID"/>
</foreign-key>
<foreign-key foreignTable="PRODUCT_CATEGORY_NAME">
<reference local="PRODUCT_CATEGORY_NAME_ID" foreign="ID"/>
</foreign-key>
</table>
and my repository:
<class-descriptor class="com.zopyra.test.tutorial2.Product"
table="PRODUCT">
<field-descriptor id="1" name="id" column="ID"
jdbc-type="INTEGER" primarykey="true" autoincrement="true"/>
<field-descriptor id="2" name="name" column="NAME"
jdbc-type="VARCHAR"/>
<field-descriptor id="3" name="price" column="PRICE"
jdbc-type="DOUBLE"/>
<field-descriptor id="4" name="discount" column="DISCOUNT"
jdbc-type="DOUBLE"/>
<field-descriptor id="5" name="stock" column="STOCK"
jdbc-type="INTEGER"/>
<collection-descriptor
name="productCategoryNames"
element-class-ref="com.zopyra.test.tutorial2.ProductCategoryName"
indirection-table="PRODUCT_CATEGORY">
<fk-pointing-to-this-class column="PRODUCT_ID"/>
<fk-pointing-to-element-class
column="PRODUCT_CATEGORY_NAME_ID"/>
</collection-descriptor>
</class-descriptor>
<class-descriptor class="com.zopyra.test.tutorial2.ProductCategoryName"
table="PRODUCT_CATEGORY_NAME">
<field-descriptor id="1" name="id" column="ID"
jdbc-type="INTEGER" primarykey="true" autoincrement="true"/>
<field-descriptor id="2" name="name" column="NAME"
jdbc-type="VARCHAR" primarykey="true" nullable="false"/>
</class-descriptor>
I would like to be able to create a Product object, populate it with
values, among them being the list of category names that represent
it. I would like then to save this to the DB by saving just the
product object. I would like also to be able to declare another
Product object, for example, populate it with two category names, one
of which might already be in the PRODUCT_CATEGORY_NAME table. When I
save this new product object, I would like it to recognize that one of
its values is already accounted for in the PRODUCT_CATEGORY_NAME
table, and to just enter the new product category name there, and make
two entries in the PRODUCT table.
I have tried another variation (which I forget at the moment) that
allowed me to insert values, but fails when I try to update with a new
Product which has category names that already exist.
If I can't express this "automatically" through OJB, how can I do it?
Surely someone has run in to this.
Sorry for the long post and thanks for any help you can offer.
Bill
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