Multiple Item Properties

You can also specify that a repository item property is a collection of repository items. In the previous example, an author may have written more than one book. Instead of the book property in the preceding example, this next example uses a books_written property whose value is a Set of book repository items. The <property> tag for the books_written property uses the following attributes:

data-type="set", to specify that the property value is a Set of items

component-item-type="book", to specify that the items making up the set are items of the book item descriptor

column-name="book_id", to specify that the database column is named book_id, rather than books_written.

<!-- The "book" item type -->

<item-descriptor name="book" default="true">

  <table name="book" type="primary" id-column-names="book_id">

    <property name="title"/>

    <property name="author" item-type="author" column-name="author_id"/>

  </table>

</item-descriptor>

<!-- The "author" item type -->

<item-descriptor name="author">

  <table name="author" id-column-names="author_id" type="primary">

    <property name="lastName"/>

    <property name="city"/>

    <property name="state"/>

    <property name="zip"/>

  </table>

  <table name="book" id-column-names="author_id" type="multi">

    <property name="books_written" data-type="set"

          component-item-type="book"

          column-name="book_id"/>

  </table>

</item-descriptor>

In this example, the book table is defined twice in the XML, first in the book item descriptor and in the author item descriptor. The second time, this table is a multi-table where each author item can have more than one row with the id column. In a multi-table, all defined attributes are multi-valued types. To defineArray, List and Map types, you also must specify a multi-column-name attribute on the table tag. This specifies which column to use as the sorting value in order to determine the order of the List and the key for the Map.

Now the properties author and books_written are actually real beans (in this case RepositoryItems) instead of just simple Java primitives. In the author item descriptor, the books_written property is a Set of RepositoryItems that correspond to books. The other types supported are List, Map, and Array.