Add way to filter hook on content model.

includes/orphaned_objects.inc

@@ -169,7 +169,7 @@ WHERE {
   FILTER (!bound(?liveparent))
 } ORDER BY ?object
 EOQ;
-  $parent_relationships = module_invoke_all('islandora_solution_pack_child_relationships');
+  $parent_relationships = module_invoke_all('islandora_solution_pack_child_relationships', 'all');
   if (count($parent_relationships['predicate']) == 0) {
     // No predicates to search for. Exit early.
     return array();

islandora.api.php

@@ -970,11 +970,19 @@ function hook_islandora_datastream_filename_alter(&$filename, AbstractDatastream
 /**
  * Allow solution packs to register relationships used for children.
  *
+ * @param string|array $cmodels
+ *   This takes either:
+ *      - string: the string 'all'. Function returns all child relationships.
+ *      - array: an array of cmodel PIDs to return the relationships for.
+ *
  * @return array
- *   - prefix (array): This is is a valid snip-it of SPARQL to register prefixes used in the predicates array.
+ *   - prefix (array): This is is a valid snip-it of SPARQL to register
- *   - predicate (array): This array contains predicates used by the solution pack for child objects.
+ *     prefixes used in the predicates array.
+ *   - predicate (array): This array contains predicates used by the solution
+ *     pack for child objects.
  */
-function hook_islandora_solution_pack_child_relationships() {
+function hook_islandora_solution_pack_child_relationships($cmodels) {
+  if ($cmodels === 'all' or in_array('my:cmodel_pid', $cmodels)) {
     return array(
       'prefix' => array('PREFIX islandora: <http://islandora.ca/ontology/relsext#>'),
       'predicate' => array(
@@ -984,3 +992,4 @@ function hook_islandora_solution_pack_child_relationships() {
       ),
     );
   }
+}

islandora.module

@@ -2219,6 +2219,8 @@ function islandora_islandora_breadcrumbs_backends() {
 /**
  * Implements hook_islandora_solution_pack_child_relationships
  */
-function islandora_islandora_solution_pack_child_relationships() {
+function islandora_islandora_solution_pack_child_relationships($cmodels) {
+  // Return empty arrays from core implementation so that these keys always
+  // exist when the hook is called, even if no module responds.
   return array('predicate' => array(), 'prefix' => array());
 }