From 01d3b4fd96cb9e6e5b2fa52a7de6067d90326dc4 Mon Sep 17 00:00:00 2001
From: Sam Minnee <sam@silverstripe.com>
Date: Mon, 26 Aug 2019 18:06:50 +1200
Subject: [PATCH] FIX: Set many-many-through joinRecord on newly added records.
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When many-many-through relations are queried, a joinRecord is set on
each DataObject in the list to provide the extra fields defined on
the connector object. This didn’t previously happen when the record
was first add()ed to a list. This fixes that bug.
---
 src/ORM/ManyManyThroughList.php           | 5 +++++
 tests/php/ORM/ManyManyThroughListTest.php | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/src/ORM/ManyManyThroughList.php b/src/ORM/ManyManyThroughList.php
index 738ff913e..93160703a 100644
--- a/src/ORM/ManyManyThroughList.php
+++ b/src/ORM/ManyManyThroughList.php
@@ -217,6 +217,11 @@ class ManyManyThroughList extends RelationList
         $record = $hasManyList->createDataObject($extraFields ?: []);
         $record->$localKey = $itemID;
         $hasManyList->add($record);
+
+        // Link the join object to the $item, as if it were queried from within this list
+        if ($item instanceof DataObject) {
+            $item->setJoin($record, $this->manipulator->getJoinAlias());
+        }
     }
 
     /**
diff --git a/tests/php/ORM/ManyManyThroughListTest.php b/tests/php/ORM/ManyManyThroughListTest.php
index 0b18cbec5..6a6b83318 100644
--- a/tests/php/ORM/ManyManyThroughListTest.php
+++ b/tests/php/ORM/ManyManyThroughListTest.php
@@ -6,6 +6,7 @@ use SilverStripe\Core\Config\Config;
 use SilverStripe\Dev\SapphireTest;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\ManyManyThroughList;
+use SilverStripe\ORM\Tests\ManyManyThroughListTest\Item;
 use SilverStripe\ORM\Tests\ManyManyThroughListTest\PolyItem;
 use SilverStripe\ORM\Tests\ManyManyThroughListTest\PolyJoinObject;
 use SilverStripe\ORM\Tests\ManyManyThroughListTest\Locale;
@@ -75,6 +76,14 @@ class ManyManyThroughListTest extends SapphireTest
         $this->assertNotNull($item2->getJoin());
         $this->assertEquals('join 2', $item2->getJoin()->Title);
         $this->assertEquals('join 2', $item2->ManyManyThroughListTest_JoinObject->Title);
+
+        // Check that the join record is set for new records added
+        $item3 = new Item;
+        $this->assertNull($item3->getJoin());
+        $parent->Items()->add($item3);
+        $expectedJoinObject = ManyManyThroughListTest\JoinObject::get()->filter(['ParentID' => $parent->ID, 'ChildID' => $item3->ID ])->first();
+        $this->assertEquals($expectedJoinObject->ID, $item3->getJoin()->ID);
+        $this->assertEquals(get_class($expectedJoinObject), get_class($item3->getJoin()));
     }
 
     /**