Allow setting a custom search items list

Closes #13. Closes #14.

code/GridFieldAddExistingSearchButton.php

@@ -9,6 +9,7 @@ class GridFieldAddExistingSearchButton implements
 
 	protected $title;
 	protected $fragment;
+	protected $searchList;
 
 	/**
 	 * @param string $fragment
@@ -46,6 +47,22 @@ class GridFieldAddExistingSearchButton implements
 		$this->fragment = $fragment;
 	}
 
+	/**
+	 * Sets a custom list to use to provide the searchable items.
+	 *
+	 * @param SS_List $list
+	 */
+	public function setSearchList(SS_List $list) {
+		$this->searchList = $list;
+	}
+
+	/**
+	 * @return SS_List|null
+	 */
+	public function getSearchList() {
+		return $this->searchList;
+	}
+
 	public function getHTMLFragments($grid) {
 		GridFieldExtensions::include_requirements();
 

code/GridFieldAddExistingSearchHandler.php

@@ -76,7 +76,7 @@ class GridFieldAddExistingSearchHandler extends RequestHandler {
 	}
 
 	public function doSearch($data, $form) {
-		$list = $this->context->getResults($data);
+		$list = $this->context->getQuery($data, false, false, $this->getSearchList());
 		$list = $list->subtract($this->grid->getList());
 		$list = new PaginatedList($list, $this->request);
 
@@ -88,7 +88,7 @@ class GridFieldAddExistingSearchHandler extends RequestHandler {
 	}
 
 	public function Items() {
-		$list = DataList::create($this->grid->getList()->dataClass());
+		$list = $this->getSearchList();
 		$list = $list->subtract($this->grid->getList());
 		$list = new PaginatedList($list, $this->request);
 
@@ -99,4 +99,11 @@ class GridFieldAddExistingSearchHandler extends RequestHandler {
 		return Controller::join_links($this->grid->Link(), 'add-existing-search', $action);
 	}
 
+	/**
+	 * @return DataList
+	 */
+	protected function getSearchList() {
+		return $this->button->getSearchList() ?: DataList::create($this->grid->getList()->dataClass());
+	}
+
 }