Use built in eloquent methods

Author: jonerickson

src/Laravel/Eloquent/State/LinksHandler.php

@@ -14,6 +14,7 @@
 namespace ApiPlatform\Laravel\Eloquent\State;
 
 use ApiPlatform\Metadata\Exception\OperationNotFoundException;
+use ApiPlatform\Metadata\Exception\RuntimeException;
 use ApiPlatform\Metadata\GraphQl\Operation;
 use ApiPlatform\Metadata\GraphQl\Query;
 use ApiPlatform\Metadata\HttpOperation;
@@ -22,7 +23,11 @@
 use Illuminate\Contracts\Foundation\Application;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Model;
-use Illuminate\Database\Eloquent\Relations\MorphOneOrMany;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+use Illuminate\Database\Eloquent\Relations\HasOneOrMany;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
+use Illuminate\Database\Eloquent\Relations\Relation;
 
 /**
  * @implements LinksHandlerInterface<Model>
@@ -102,41 +107,44 @@ private function buildQuery(Builder $builder, Link $link, mixed $identifier): Bu
         }
 
         if ($from = $link->getFromProperty()) {
-            $relation = $this->application->make($link->getFromClass());
-            $relationQuery = $relation->{$from}();
+            /** @var Model $relatedInstance */
+            $relatedInstance = $this->application->make($link->getFromClass());
+            $relatedInstance->setAttribute($relatedInstance->getKeyName(), $identifier);
+            $relatedInstance->exists = true;
 
-            if ($relationQuery instanceof MorphOneOrMany) {
-                return $builder
-                    ->where($relationQuery->getForeignKeyName(), $identifier)
-                    ->where($relationQuery->getMorphType(), $relationQuery->getMorphClass());
+            /** @var Relation<Model, Model, mixed> $relation */
+            $relation = $relatedInstance->{$from}();
+
+            if ($relation instanceof MorphTo) {
+                throw new RuntimeException('Cannot query directly from a MorphTo relationship.');
             }
 
-            if (!method_exists($relationQuery, 'getQualifiedForeignKeyName') && method_exists($relationQuery, 'getQualifiedForeignPivotKeyName')) {
+            if ($relation instanceof BelongsTo) {
                 return $builder->getModel()
                     ->join(
-                        $relationQuery->getTable(), // @phpstan-ignore-line
-                        $relationQuery->getQualifiedRelatedPivotKeyName(), // @phpstan-ignore-line
-                        $builder->getModel()->getQualifiedKeyName()
-                    )
-                    ->where(
-                        $relationQuery->getQualifiedForeignPivotKeyName(), // @phpstan-ignore-line
+                        $relation->getParent()->getTable(),
+                        $relation->getParent()->getQualifiedKeyName(),
                         $identifier
-                    )
-                    ->select($builder->getModel()->getTable().'.*');
+                    );
             }
 
-            if (method_exists($relationQuery, 'dissociate')) {
-                return $builder->getModel()
-                       ->join(
-                           $relationQuery->getParent()->getTable(), // @phpstan-ignore-line
-                           $relationQuery->getParent()->getQualifiedKeyName(), // @phpstan-ignore-line
-                           $identifier
-                       );
+            if ($relation instanceof HasOneOrMany || $relation instanceof BelongsToMany) {
+                return $relation->getQuery();
+            }
+
+            if (method_exists($relation, 'getQualifiedForeignKeyName')) {
+                return $relation->getQuery()->where(
+                    $relation->getQualifiedForeignKeyName(),
+                    $identifier
+                );
             }
 
-            return $builder->getModel()->where($relationQuery->getQualifiedForeignKeyName(), $identifier);
+            throw new RuntimeException(\sprintf('Unhandled or unknown relationship type: %s for property %s on %s', $relation::class, $from, $relatedInstance::class));
         }
 
-        return $builder->where($builder->getModel()->qualifyColumn($link->getIdentifiers()[0]), $identifier);
+        return $builder->where(
+            $builder->getModel()->qualifyColumn($link->getIdentifiers()[0]),
+            $identifier
+        );
     }
 }

src/Laravel/Tests/EloquentTest.php

@@ -447,6 +447,17 @@ public function testBelongsTo(): void
         $this->assertEquals($json['sons'][0], '/api/grand_sons/1');
     }
 
+    public function testHasMany(): void
+    {
+        GrandSonFactory::new()->count(1)->create();
+
+        $res = $this->get('/api/grand_fathers/1/grand_sons', ['Accept' => ['application/ld+json']]);
+        $json = $res->json();
+        $this->assertEquals($json['@id'], '/api/grand_fathers/1/grand_sons');
+        $this->assertEquals($json['totalItems'], 1);
+        $this->assertEquals($json['member'][0]['@id'], '/api/grand_sons/1');
+    }
+
     public function testRelationIsHandledOnCreateWithNestedData(): void
     {
         $cartData = [