[11.x] Handle circular references in model serialization

src/Illuminate/Database/Eloquent/Concerns/PreventsCircularRecursion.php

@@ -0,0 +1,74 @@
+<?php
+
+namespace Illuminate\Database\Eloquent\Concerns;
+
+use Illuminate\Support\Arr;
+use Illuminate\Support\Onceable;
+
+trait PreventsCircularRecursion
+{
+    /**
+     * The cache of objects processed to prevent infinite recursion.
+     *
+     * @var \WeakMap<static, array<string, mixed>>
+     */
+    protected static $recursionCache;
+
+    /**
+     * Get the current recursion cache being used by the model.
+     *
+     * @return \WeakMap
+     */
+    protected static function getRecursionCache()
+    {
+        return static::$recursionCache ??= new \WeakMap();
+    }
+
+    /**
+     * Get the current stack of methods being called recursively.
+     *
+     * @param  object  $object
+     * @return array
+     */
+    protected static function getRecursiveCallStack($object): array
+    {
+        return static::getRecursionCache()->offsetExists($object)
+            ? static::getRecursionCache()->offsetGet($object)
+            : [];
+    }
+
+    /**
+     * Prevent a method from being called multiple times on the same object within the same call stack.
+     *
+     * @param  callable  $callback
+     * @param  mixed  $default
+     * @return mixed
+     */
+    protected function once($callback, $default = null)
+    {
+        $trace = debug_backtrace(DEBUG_BACKTRACE_PROVIDE_OBJECT, 2);
+
+        $onceable = Onceable::tryFromTrace($trace, $callback);
+
+        $object = $onceable->object ?? $this;
+        $stack = static::getRecursiveCallStack($object);
+
+        if (isset($stack[$onceable->hash])) {
+            return $stack[$onceable->hash];
+        }
+
+        try {
+            // Set the default first to prevent recursion
+            $stack[$onceable->hash] = $default;
+            static::getRecursionCache()->offsetSet($object, $stack);
+
+            return call_user_func($onceable->callable);
+        } finally {
+            if ($stack = Arr::except($this->getRecursiveCallStack($object), $onceable->hash)) {
+                static::getRecursionCache()->offsetSet($object, $stack);
+            } elseif (static::getRecursionCache()->offsetExists($object)) {
+                static::getRecursionCache()->offsetUnset($object);
+            }
+        }
+    }
+}

src/Illuminate/Database/Eloquent/Model.php

@@ -35,6 +35,7 @@ abstract class Model implements Arrayable, ArrayAccess, CanBeEscapedWhenCastToSt
         Concerns\HasUniqueIds,
         Concerns\HidesAttributes,
         Concerns\GuardsAttributes,
+        Concerns\PreventsCircularRecursion,
         ForwardsCalls;
     /** @use HasCollection<\Illuminate\Database\Eloquent\Collection<array-key, static>> */
     use HasCollection;
@@ -1083,25 +1084,27 @@ protected function decrementQuietly($column, $amount = 1, array $extra = [])
      */
     public function push()
     {
-        if (! $this->save()) {
-            return false;
-        }
-
-        // To sync all of the relationships to the database, we will simply spin through
-        // the relationships and save each model via this "push" method, which allows
-        // us to recurse into all of these nested relations for the model instance.
-        foreach ($this->relations as $models) {
-            $models = $models instanceof Collection
-                ? $models->all() : [$models];
+        return $this->once(function () {
+            if (! $this->save()) {
+                return false;
+            }
 
-            foreach (array_filter($models) as $model) {
-                if (! $model->push()) {
-                    return false;
+            // To sync all of the relationships to the database, we will simply spin through
+            // the relationships and save each model via this "push" method, which allows
+            // us to recurse into all of these nested relations for the model instance.
+            foreach ($this->relations as $models) {
+                $models = $models instanceof Collection
+                    ? $models->all() : [$models];
+
+                foreach (array_filter($models) as $model) {
+                    if (! $model->push()) {
+                        return false;
+                    }
                 }
             }
-        }
 
-        return true;
+            return true;
+        }, true);
     }
 
     /**
@@ -1644,7 +1647,10 @@ public function callNamedScope($scope, array $parameters = [])
      */
     public function toArray()
     {
-        return array_merge($this->attributesToArray(), $this->relationsToArray());
+        return $this->once(
+            fn () => array_merge($this->attributesToArray(), $this->relationsToArray()),
+            $this->attributesToArray(),
+        );
     }
 
     /**
@@ -1991,29 +1997,31 @@ public function getQueueableId()
      */
     public function getQueueableRelations()
     {
-        $relations = [];
+        return $this->once(function () {
+            $relations = [];
 
-        foreach ($this->getRelations() as $key => $relation) {
-            if (! method_exists($this, $key)) {
-                continue;
-            }
+            foreach ($this->getRelations() as $key => $relation) {
+                if (! method_exists($this, $key)) {
+                    continue;
+                }
 
-            $relations[] = $key;
+                $relations[] = $key;
 
-            if ($relation instanceof QueueableCollection) {
-                foreach ($relation->getQueueableRelations() as $collectionValue) {
-                    $relations[] = $key.'.'.$collectionValue;
+                if ($relation instanceof QueueableCollection) {
+                    foreach ($relation->getQueueableRelations() as $collectionValue) {
+                        $relations[] = $key.'.'.$collectionValue;
+                    }
                 }
-            }
 
-            if ($relation instanceof QueueableEntity) {
-                foreach ($relation->getQueueableRelations() as $entityValue) {
-                    $relations[] = $key.'.'.$entityValue;
+                if ($relation instanceof QueueableEntity) {
+                    foreach ($relation->getQueueableRelations() as $entityValue) {
+                        $relations[] = $key.'.'.$entityValue;
+                    }
                 }
             }
-        }
 
-        return array_unique($relations);
+            return array_unique($relations);
+        }, []);
     }
 
     /**

tests/Database/DatabaseConcernsPreventsCircularRecursionTest.php

@@ -0,0 +1,162 @@
+<?php
+
+namespace Illuminate\Tests\Database;
+
+use Illuminate\Database\Eloquent\Concerns\PreventsCircularRecursion;
+use PHPUnit\Framework\TestCase;
+
+class DatabaseConcernsPreventsCircularRecursionTest extends TestCase
+{
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        PreventsCircularRecursionWithRecursiveMethod::$globalStack = 0;
+    }
+
+    public function testRecursiveCallsArePreventedWithoutPreventingSubsequentCalls()
+    {
+        $instance = new PreventsCircularRecursionWithRecursiveMethod();
+
+        $this->assertEquals(0, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(0, $instance->instanceStack);
+
+        $this->assertEquals(0, $instance->callStack());
+        $this->assertEquals(1, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(1, $instance->instanceStack);
+
+        $this->assertEquals(1, $instance->callStack());
+        $this->assertEquals(2, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(2, $instance->instanceStack);
+    }
+
+    public function testRecursiveCallsAreLimitedToIndividualInstances()
+    {
+        $instance = new PreventsCircularRecursionWithRecursiveMethod();
+        $other = $instance->other;
+
+        $this->assertEquals(0, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(0, $instance->instanceStack);
+        $this->assertEquals(0, $other->instanceStack);
+
+        $instance->callStack();
+        $this->assertEquals(1, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(1, $instance->instanceStack);
+        $this->assertEquals(0, $other->instanceStack);
+
+        $instance->callStack();
+        $this->assertEquals(2, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(2, $instance->instanceStack);
+        $this->assertEquals(0, $other->instanceStack);
+
+        $other->callStack();
+        $this->assertEquals(3, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(2, $instance->instanceStack);
+        $this->assertEquals(1, $other->instanceStack);
+
+        $other->callStack();
+        $this->assertEquals(4, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(2, $instance->instanceStack);
+        $this->assertEquals(2, $other->instanceStack);
+    }
+
+    public function testRecursiveCallsToCircularReferenceCallsOtherInstanceOnce()
+    {
+        $instance = new PreventsCircularRecursionWithRecursiveMethod();
+        $other = $instance->other;
+
+        $this->assertEquals(0, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(0, $instance->instanceStack);
+        $this->assertEquals(0, $other->instanceStack);
+
+        $instance->callOtherStack();
+        $this->assertEquals(2, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(1, $instance->instanceStack);
+        $this->assertEquals(1, $other->instanceStack);
+
+        $instance->callOtherStack();
+        $this->assertEquals(4, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(2, $instance->instanceStack);
+        $this->assertEquals(2, $other->instanceStack);
+
+        $other->callOtherStack();
+        $this->assertEquals(6, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(3, $other->instanceStack);
+        $this->assertEquals(3, $instance->instanceStack);
+
+        $other->callOtherStack();
+        $this->assertEquals(8, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(4, $other->instanceStack);
+        $this->assertEquals(4, $instance->instanceStack);
+    }
+
+    public function testRecursiveCallsToCircularLinkedListCallsEachInstanceOnce()
+    {
+        $instance = new PreventsCircularRecursionWithRecursiveMethod();
+        $second = $instance->other;
+        $third = new PreventsCircularRecursionWithRecursiveMethod($second);
+        $instance->other = $third;
+
+        $this->assertEquals(0, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(0, $instance->instanceStack);
+        $this->assertEquals(0, $second->instanceStack);
+        $this->assertEquals(0, $third->instanceStack);
+
+        $instance->callOtherStack();
+        $this->assertEquals(3, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(1, $instance->instanceStack);
+        $this->assertEquals(1, $second->instanceStack);
+        $this->assertEquals(1, $third->instanceStack);
+
+        $second->callOtherStack();
+        $this->assertEquals(6, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(2, $instance->instanceStack);
+        $this->assertEquals(2, $second->instanceStack);
+        $this->assertEquals(2, $third->instanceStack);
+
+        $third->callOtherStack();
+        $this->assertEquals(9, PreventsCircularRecursionWithRecursiveMethod::$globalStack);
+        $this->assertEquals(3, $instance->instanceStack);
+        $this->assertEquals(3, $second->instanceStack);
+        $this->assertEquals(3, $third->instanceStack);
+    }
+}
+
+class PreventsCircularRecursionWithRecursiveMethod
+{
+    use PreventsCircularRecursion;
+
+    public function __construct(
+        public ?PreventsCircularRecursionWithRecursiveMethod $other = null,
+    ) {
+        $this->other ??= new PreventsCircularRecursionWithRecursiveMethod($this);
+    }
+
+    public static int $globalStack = 0;
+    public int $instanceStack = 0;
+
+    public function callStack(): int
+    {
+        return $this->once(
+            function () {
+                static::$globalStack++;
+                $this->instanceStack++;
+
+                return $this->callStack();
+            },
+            $this->instanceStack
+        );
+    }
+
+    public function callOtherStack(): int
+    {
+        return $this->once(
+            function () {
+                $this->other->callStack();
+
+                return $this->other->callOtherStack();
+            },
+            $this->instanceStack
+        );
+    }
+}