Добавление полей в $_modx->resource.

<object class="hdOrder" extends="modResource">
        <composite alias="Data" class="hdOrderData" local="id" foreign="id" cardinality="one" owner="local"/>
    </object>

    <object class="hdOrderData" table="hd_orders" extends="xPDOSimpleObject">
        <field key="contact" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="true"/>

        <index alias="contact" name="contact" primary="false" unique="false" type="BTREE">
            <column key="contact" length="" collation="A" null="false"/>
        </index>

        <aggregate alias="Order" class="hdOrder" local="id" foreign="id" cardinality="one" owner="foreign"/>
    </object>

case 'OnLoadWebDocument':
        // Set product fields as [[*resource]] tags
        if ($modx->resource->get('template') === 7) {
            if ($dataMeta = $modx->getFieldMeta('hdOrderData')) {
                unset($dataMeta['id']);
                $modx->resource->_fieldMeta = array_merge(
                    $modx->resource->_fieldMeta,
                    $dataMeta
                );
            }
        }
        break;