FIX GridFieldOrderableRows to support polymorphic ManyManyThroughList

src/GridFieldOrderableRows.php

@@ -715,7 +715,7 @@ class GridFieldOrderableRows extends RequestHandler implements
                 $introspector->getExtraFields() :
                 DataObjectSchema::create()->fieldSpecs($introspector->getJoinClass(), DataObjectSchema::DB_ONLY);
             $key   = $introspector->getLocalKey();
-            $foreignKey = $introspector->getForeignKey();
+            $foreignKey = $this->getManyManyInspectorForeignKey($introspector);
             $foreignID  = (int) $list->getForeignID();
 
             if ($extra && array_key_exists($this->getSortField(), $extra)) {
@@ -755,6 +755,24 @@ class GridFieldOrderableRows extends RequestHandler implements
         return $inspector;
     }
 
+
+    /**
+     * Depending on the list inspector and the list itself (ManyMany vs ManyManyThrough), the method to obtain
+     * the foreign key may be different.
+     *
+     * @param $inspector
+     * @return string
+     */
+    private function getManyManyInspectorForeignKey($inspector)
+    {
+        if (($inspector instanceof ManyManyThroughQueryManipulator) && (method_exists($inspector, 'getForeignIDKey'))) {
+            // This method has been introduced in framework 4.1
+            return $inspector->getForeignIDKey();
+        }
+
+        return $inspector->getForeignKey();
+    }
+
     /**
      * Used to get sort orders from a many many through list relationship record, rather than the current
      * record itself.
@@ -768,7 +786,7 @@ class GridFieldOrderableRows extends RequestHandler implements
 
         // Find the foreign key name, ID and class to look up
         $joinClass = $manipulator->getJoinClass();
-        $fromRelationName = $manipulator->getForeignKey();
+        $fromRelationName = $this->getManyManyInspectorForeignKey($manipulator);
         $toRelationName = $manipulator->getLocalKey();
 
         // Create a list of the MMTL relations

tests/GridFieldOrderableRowsTest.php

@@ -7,6 +7,9 @@ use SilverStripe\Dev\SapphireTest;
 use SilverStripe\Forms\GridField\GridField;
 use SilverStripe\Forms\GridField\GridFieldConfig_RelationEditor;
 use Symbiote\GridFieldExtensions\GridFieldOrderableRows;
+use Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MChild;
+use Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MMapper;
+use Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MParent;
 use Symbiote\GridFieldExtensions\Tests\Stub\StubOrderableChild;
 use Symbiote\GridFieldExtensions\Tests\Stub\StubOrdered;
 use Symbiote\GridFieldExtensions\Tests\Stub\StubOrderedVersioned;
@@ -25,10 +28,14 @@ class GridFieldOrderableRowsTest extends SapphireTest
 {
     protected static $fixture_file = [
         'GridFieldOrderableRowsTest.yml',
-        'OrderableRowsThroughTest.yml'
+        'OrderableRowsThroughTest.yml',
+        // 'OrderablePolymorphicManyToMany.yml'  // TODO: introduce this tests in the next minor release
     ];
 
     protected static $extra_dataobjects = [
+        // PolymorphM2MChild::class,
+        // PolymorphM2MMapper::class,
+        // PolymorphM2MParent::class,
         StubParent::class,
         StubOrdered::class,
         StubSubclass::class,
@@ -46,6 +53,7 @@ class GridFieldOrderableRowsTest extends SapphireTest
         return [
             [StubParent::class . '.parent', 'MyManyMany', 'ManyManySort'],
             [ThroughDefiner::class . '.DefinerOne', 'Belongings', 'Sort'],
+            // [PolymorphM2MParent::class . '.ParentOne', 'Children', 'Sort']
         ];
     }
 
@@ -122,6 +130,40 @@ class GridFieldOrderableRowsTest extends SapphireTest
         );
     }
 
+    public function testPolymorphicManyManyListSortOrdersAreUsedForInitialRender()
+    {
+        $this->markTestSkipped('TODO: Introduce this test in the next minor release (3.3)');
+
+        $record = $this->objFromFixture(PolymorphM2MParent::class, 'ParentOne');
+
+        $orderable = new GridFieldOrderableRows('Sort');
+        $config = new GridFieldConfig_RelationEditor();
+        $config->addComponent($orderable);
+
+        $grid = new GridField(
+            'Children',
+            'Testing Polymorphic Many Many',
+            $record->Children()->sort('Sort'),
+            $config
+        );
+
+        // Get the first record, which would be the first one to have column contents generated
+        $intermediary = $this->objFromFixture(PolymorphM2MMapper::class, 'MapP1ToC1');
+
+        $result = $orderable->getColumnContent($grid, $record, 'irrelevant');
+
+        $this->assertContains(
+            'Children[GridFieldEditableColumns][' . $record->ID . '][Sort]',
+            $result,
+            'The field name is indexed under the record\'s ID'
+        );
+        $this->assertContains(
+            'value="' . $intermediary->Sort . '"',
+            $result,
+            'The value comes from the MMTL intermediary Sort value'
+        );
+    }
+
     public function testSortableChildClass()
     {
         $orderable = new GridFieldOrderableRows('Sort');

tests/OrderablePolymorphicManyToMany.yml

@@ -0,0 +1,28 @@
+Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MParent:
+  ParentOne:
+  ParentTwo:
+
+Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MChild:
+  ChildOne:
+  ChildTwo:
+
+Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MMapper:
+  MapP1ToC1:
+    Parent: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MParent.ParentOne'
+    Child: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MChild.ChildOne'
+    Sort: 1
+
+  MapP1ToC2:
+    Parent: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MParent.ParentOne'
+    Child: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MChild.ChildTwo'
+    Sort: 2
+
+  MapP2ToC1:
+    Parent: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MParent.ParentTwo'
+    Child: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MChild.ChildOne'
+    Sort: 2
+
+  MapP2ToC2:
+    Parent: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MParent.ParentTwo'
+    Child: '=>Symbiote\GridFieldExtensions\Tests\Stub\PolymorphM2MChild.ChildTwo'
+    Sort: 1

tests/Stub/PolymorphM2MChild.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Symbiote\GridFieldExtensions\Tests\Stub;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class PolymorphM2MChild extends DataObject implements TestOnly
+{
+    private static $table_name = 'TestOnly_PolymorphM2MChild';
+
+    private static $has_many = [
+        'Parents' => PolymorphM2MMapper::class
+    ];
+}

tests/Stub/PolymorphM2MMapper.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Symbiote\GridFieldExtensions\Tests\Stub;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class PolymorphM2MMapper extends DataObject implements TestOnly
+{
+    private static $table_name = 'TestOnly_PolymorphM2MMapper';
+
+    private static $db = [
+        'Sort' => 'Int'
+    ];
+
+    private static $has_one = [
+        'Parent' => DataObject::class, // PolymorphM2MParent
+        'Child' => PolymorphM2MChild::class,
+    ];
+
+    private static $default_sort = '"Sort" ASC';
+}

tests/Stub/PolymorphM2MParent.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Symbiote\GridFieldExtensions\Tests\Stub;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class PolymorphM2MParent extends DataObject implements TestOnly
+{
+    private static $table_name = 'TableOnly_PolymorphM2MParent';
+
+    private static $many_many = [
+        'Children' => [
+            'through' => PolymorphM2MMapper::class,
+            'from' => 'Parent',
+            'to' => 'Child',
+        ]
+    ];
+}