Refactors

src/EntryRelationship.php

@@ -14,6 +14,10 @@ class EntryRelationship
 
     const TYPE_MANY_TO_ONE = 4;
 
+    public ?EntryRelationship $origin = null;
+
+    public ?EntryRelationship $inverted = null;
+
     public $leftType = '';
 
     public $rightType = '';
@@ -115,6 +119,14 @@ public function withEvents($withEvents = true)
         return $this;
     }
 
+    public function withOriginRelationship(EntryRelationship $relationship)
+    {
+        $this->origin = $relationship;
+        $relationship->inverted = $this;
+
+        return $this;
+    }
+
     public function isAutomaticInverse($isInverse = true, $inverseIndex = null)
     {
         $this->isAutomaticInverse = $isInverse;
@@ -128,6 +140,15 @@ public function isAutomaticInverse($isInverse = true, $inverseIndex = null)
         return $this;
     }
 
+    public function getInverse()
+    {
+        if ($this->isAutomaticInverse) {
+            return $this->origin;
+        }
+
+        return $this->inverted;
+    }
+
     /**
      * Sets whether affected entries will be updated when deleting related entries.
      *

src/Listeners/EntrySavedListener.php

@@ -31,7 +31,7 @@ public function handle(EntrySaved $event)
             return;
         }
 
-        if (EventStack::count() > 0 || $this->manager->processor()->isProcessingManyToMany()) {
+        if (EventStack::count() > 0 || $this->manager->processor()->isProcessingRelationships()) {
             return;
         }
 

src/Listeners/EntrySavingListener.php

@@ -38,7 +38,7 @@ public function handle(EntrySaving $event)
             return;
         }
 
-        if (EventStack::count() > 1 || $this->manager->processor()->isProcessingManyToMany()) {
+        if (EventStack::count() > 1 || $this->manager->processor()->isProcessingRelationships()) {
             return;
         }
 

src/Processors/Concerns/ProcessesManyToMany.php

@@ -9,7 +9,7 @@ trait ProcessesManyToMany
 {
     protected function processManyToMany(ComparisonResult $results, EntryRelationship $relationship)
     {
-        $this->processingManyToMany = true;
+        $this->processingRelationships = true;
 
         foreach ($results->added as $addedId) {
             if (! $this->shouldProcessRelationship($relationship, $addedId)) {
@@ -27,6 +27,6 @@ protected function processManyToMany(ComparisonResult $results, EntryRelationshi
             $this->removeItemFromEntry($relationship, $this->getEffectedEntity($relationship, $removedId));
         }
 
-        $this->processingManyToMany = false;
+        $this->processingRelationships = false;
     }
 }

src/Processors/Concerns/ProcessesOneToMany.php

@@ -2,6 +2,7 @@
 
 namespace Stillat\Relationships\Processors\Concerns;
 
+use Statamic\Facades\Data;
 use Stillat\Relationships\Comparisons\ComparisonResult;
 use Stillat\Relationships\EntryRelationship;
 
@@ -11,12 +12,29 @@ protected function processOneToMany(ComparisonResult $results, EntryRelationship
     {
         foreach ($results->removed as $removedId) {
             if ($this->shouldProcessRelationship($relationship, $removedId)) {
+                $this->dependencies[] = $removedId;
+                $this->dependencies[] = $this->getDependency($relationship, $removedId);
                 $this->removeFieldValue($relationship, $this->getEffectedEntity($relationship, $removedId));
             }
         }
 
         foreach ($results->added as $addedId) {
             if ($this->shouldProcessRelationship($relationship, $addedId)) {
+                $this->dependencies[] = $addedId;
+                $dependent = Data::find($this->getDependency($relationship, $addedId));
+
+                if ($dependent !== null && $inverse = $relationship->getInverse()) {
+                    $leftReference = $dependent->get($relationship->leftField);
+
+                    if (($key = array_search($addedId, $leftReference)) !== false) {
+                        unset($leftReference[$key]);
+
+                        $dependent->set($relationship->leftField, array_values($leftReference));
+
+                        $dependent->saveQuietly();
+                    }
+                }
+
                 $this->setFieldValue($relationship, $this->getEffectedEntity($relationship, $addedId));
             }
         }

src/Processors/RelationshipProcessor.php

@@ -87,11 +87,13 @@ class RelationshipProcessor
 
     protected $observed = [];
 
-    protected $processingManyToMany = false;
+    protected $processingRelationships = false;
 
-    public function isProcessingManyToMany()
+    protected $dependencies = [];
+
+    public function isProcessingRelationships()
     {
-        return $this->processingManyToMany;
+        return $this->processingRelationships;
     }
 
     public function setIsDeleting($isDeleting = true)
@@ -307,9 +309,11 @@ public function process($relationships)
 
     public function processRelationship($relationship, $results)
     {
+        $this->processingRelationships = true;
         UpdatingRelationshipsEvent::dispatch($relationship, $results);
 
         if (! $results->hasChanges()) {
+            $this->processingRelationships = false;
             UpdatedRelationshipsEvent::dispatch($relationship, $results);
 
             return;
@@ -326,6 +330,7 @@ public function processRelationship($relationship, $results)
         } elseif ($relationship->type == EntryRelationship::TYPE_MANY_TO_ONE) {
             $this->processManyToOne($results, $relationship);
         }
+        $this->processingRelationships = false;
 
         UpdatedRelationshipsEvent::dispatch($relationship, $results);
     }
@@ -354,6 +359,25 @@ protected function shouldProcessRelationship(EntryRelationship $relationship, $i
         return true;
     }
 
+    protected function getDependency(EntryRelationship $relationship, $id)
+    {
+        $data = null;
+
+        if ($relationship->rightType == 'entry') {
+            $data = $this->effectedEntries[$id];
+        } elseif ($relationship->rightType == 'user') {
+            $data = $this->effectedUsers[$id];
+        } elseif ($relationship->rightType == 'term') {
+            $data = $this->effectedTerms[$id];
+        }
+
+        if ($data === null || ! method_exists($data, 'get')) {
+            return null;
+        }
+
+        return $data->get($relationship->rightField);
+    }
+
     protected function getEffectedEntity(EntryRelationship $relationship, $id)
     {
         if ($relationship->rightType == 'entry') {

src/RelationshipManager.php

@@ -125,7 +125,10 @@ private function buildOneToOneRelationships($relationships)
             $right = $this->getFieldDetails($relationship[1]);
 
             $builtRelationships[] = $this->getRelationship($left, $right)->oneToOne();
-            $builtRelationships[] = $this->getRelationship($right, $left)->oneToOne()->isAutomaticInverse();
+            $builtRelationships[] = $this->getRelationship($right, $left)
+                ->oneToOne()
+                ->isAutomaticInverse()
+                ->withOriginRelationship($builtRelationships[0]);
         }
 
         return new RelationshipProxy($builtRelationships);
@@ -150,7 +153,10 @@ private function buildOneToManyRelationships($relationships)
             $right = $this->getFieldDetails($relationship[1]);
 
             $builtRelationships[] = $this->getRelationship($left, $right)->manyToOne();
-            $builtRelationships[] = $this->getRelationship($right, $left)->oneToMany()->isAutomaticInverse();
+            $builtRelationships[] = $this->getRelationship($right, $left)
+                ->oneToMany()
+                ->isAutomaticInverse()
+                ->withOriginRelationship($builtRelationships[0]);
         }
 
         return new RelationshipProxy($builtRelationships);
@@ -175,7 +181,10 @@ private function buildManyToOneRelationships($relationships)
             $right = $this->getFieldDetails($relationship[1]);
 
             $builtRelationships[] = $this->getRelationship($left, $right)->oneToOne();
-            $builtRelationships[] = $this->getRelationship($right, $left)->manyToOne()->isAutomaticInverse();
+            $builtRelationships[] = $this->getRelationship($right, $left)
+                ->manyToOne()
+                ->isAutomaticInverse()
+                ->withOriginRelationship($builtRelationships[0]);
         }
 
         return new RelationshipProxy($builtRelationships);
@@ -254,7 +263,10 @@ private function buildManyToManyRelationships($relationships)
             $right = $this->getFieldDetails($relationship[1]);
 
             $builtRelationships[] = $this->getRelationship($left, $right)->manyToMany();
-            $builtRelationships[] = $this->getRelationship($right, $left)->manyToMany()->isAutomaticInverse();
+            $builtRelationships[] = $this->getRelationship($right, $left)
+                ->manyToMany()
+                ->isAutomaticInverse()
+                ->withOriginRelationship($builtRelationships[0]);
         }
 
         return new RelationshipProxy($builtRelationships);

tests/OneToManyTest.php

@@ -117,4 +117,54 @@ public function test_one_to_many_term_relationships()
         $this->assertSame([], $this->getTerm('topics-one')->get('posts', []));
         $this->assertSame([], $this->getTerm('topics-two')->get('posts', []));
     }
+
+    public function test_one_to_many_updates_dependents()
+    {
+        Relate::clear();
+        Relate::oneToMany(
+            'books.author',
+            'authors.books'
+        );
+
+        Entry::find('books-1')->set('author', 'authors-1')->save();
+        Entry::find('books-2')->set('author', 'authors-1')->save();
+        Entry::find('books-3')->set('author', 'authors-1')->save();
+
+        Entry::find('books-4')->set('author', 'authors-1')->save();
+        Entry::find('books-5')->set('author', 'authors-2')->save();
+
+        Entry::find('authors-1')->set('books', [
+            'books-1',
+            'books-2',
+            'books-3',
+        ])->save();
+
+        Entry::find('authors-2')->set('books', [
+            'books-4',
+            'books-5',
+        ])->save();
+
+        Entry::find('authors-1')->set('books', [
+            'books-1',
+            'books-2',
+            'books-3',
+            'books-4',
+        ])->save();
+
+        $this->assertSame(['books-5'], Entry::find('authors-2')->get('books'));
+
+        $this->assertSame([
+            'books-1',
+            'books-2',
+            'books-3',
+            'books-4',
+        ], Entry::find('authors-1')->get('books'));
+
+        $this->assertSame('authors-1', Entry::find('books-1')->get('author'));
+        $this->assertSame('authors-1', Entry::find('books-2')->get('author'));
+        $this->assertSame('authors-1', Entry::find('books-3')->get('author'));
+        $this->assertSame('authors-1', Entry::find('books-4')->get('author'));
+
+        $this->assertSame('authors-2', Entry::find('books-5')->get('author'));
+    }
 }

tests/RelationshipTestCase.php

@@ -157,6 +157,15 @@ protected function createCollectionEntries()
             [
                 'title' => 'Book Two',
             ],
+            [
+                'title' => 'Book Three',
+            ],
+            [
+                'title' => 'Book Four',
+            ],
+            [
+                'title' => 'Book Five',
+            ],
         ]);
 
         $this->createEntries('conferences', [