fix(core): filtering using deeply nested relations

src/Contracts/RelationsResolver.php

@@ -13,6 +13,10 @@ public function __construct(array $includableRelations, array $alwaysIncludedRel
 
     public function requestedRelations(Request $request): array;
 
+    public function relationInstanceFromParamConstraint(string $resourceModelClass, string $paramConstraint): Relation;
+
+    public function rootRelationFromParamConstraint(string $paramConstraint): string;
+
     public function relationFromParamConstraint(string $paramConstraint): string;
 
     public function relationFieldFromParamConstraint(string $paramConstraint): string;

src/Drivers/Standard/QueryBuilder.php

@@ -134,8 +134,7 @@ public function applyFiltersToQuery($query, Request $request, array $filterDescr
                 if ($relation === 'pivot') {
                     $this->buildPivotFilterQueryWhereClause($relationField, $filterDescriptor, $query, $or);
                 } else {
-                    $relationInstance = (new $this->resourceModelClass)->{$relation}();
-
+                    $relationInstance = $this->relationsResolver->relationInstanceFromParamConstraint($this->resourceModelClass, $filterDescriptor['field']);
                     $qualifiedRelationFieldName = $this->relationsResolver->getQualifiedRelationFieldName($relationInstance, $relationField);
 
                     $query->{$or ? 'orWhereHas' : 'whereHas'}(

src/Drivers/Standard/RelationsResolver.php

@@ -5,8 +5,10 @@
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasOne;
+use Illuminate\Database\Eloquent\Relations\MorphMany;
 use Illuminate\Database\Eloquent\Relations\MorphOne;
 use Illuminate\Database\Eloquent\Relations\MorphTo;
+use Illuminate\Database\Eloquent\Relations\MorphToMany;
 use Illuminate\Database\Eloquent\Relations\Relation;
 use Illuminate\Support\Arr;
 use Illuminate\Support\Collection;
@@ -79,6 +81,37 @@ public function requestedRelations(Request $request): array
         return $validatedIncludes;
     }
 
+    public function relationInstanceFromParamConstraint(string $resourceModelClass, string $paramConstraint): Relation
+    {
+        $resourceModel = new $resourceModelClass();
+
+        do {
+            $relationName = $this->rootRelationFromParamConstraint($paramConstraint);
+            $paramConstraint = str_replace("{$relationName}.", '', $paramConstraint);
+
+            $relation = $resourceModel->{$relationName}();
+
+            if (in_array(get_class($relation), [MorphTo::class, MorphMany::class, MorphToMany::class, MorphOne::class])) {
+                break;
+            }
+
+            $resourceModel = $relation->getModel();
+        } while (str_contains($paramConstraint, '.'));
+
+        return $relation;
+    }
+
+    /**
+     * Resolves relation name from the given param constraint.
+     *
+     * @param string $paramConstraint
+     * @return string
+     */
+    public function rootRelationFromParamConstraint(string $paramConstraint): string
+    {
+        return Arr::first(explode('.', $paramConstraint));
+    }
+
     /**
      * Resolves relation name from the given param constraint.
      *
@@ -139,7 +172,7 @@ public function relationForeignKeyFromRelationInstance(Relation $relationInstanc
      */
     public function getQualifiedRelationFieldName(Relation $relation, string $field): string
     {
-        if ($relation instanceof MorphTo) {
+        if (in_array(get_class($relation), [MorphTo::class, MorphMany::class, MorphToMany::class, MorphOne::class])) {
             return $field;
         }
 

tests/Feature/StandardIndexFilteringOperationsTest.php

@@ -351,6 +351,35 @@ public function getting_a_list_of_resources_filtered_by_relation_field_resources
         );
     }
 
+    /** @test */
+    public function getting_a_list_of_resources_filtered_by_deep_relation_field_resources(): void
+    {
+        $matchingPostUser = factory(User::class)->create(['name' => 'match']);
+        $matchingPostUser->roles()->create(['name' => 'matching-role-name']);
+        $matchingPost = factory(Post::class)->create(['user_id' => $matchingPostUser->id])->fresh();
+
+        $nonMatchingPostUser = factory(User::class)->create(['name' => 'not match']);
+        $nonMatchingPostUser->roles()->create(['name' => 'non-matching-role-name']);
+        factory(Post::class)->create(['user_id' => $nonMatchingPostUser->id])->fresh();
+
+        Gate::policy(Post::class, GreenPolicy::class);
+
+        $response = $this->post(
+            '/api/posts/search',
+            [
+                'filters' => [
+                    ['field' => 'user.name', 'operator' => '=', 'value' => 'match'],
+                    ['field' => 'user.roles.name', 'operator' => '=', 'value' => 'matching-role-name'],
+                ],
+            ]
+        );
+
+        $this->assertResourcesPaginated(
+            $response,
+            $this->makePaginator([$matchingPost], 'posts/search')
+        );
+    }
+
     /** @test */
     public function getting_a_list_of_resources_filtered_by_not_whitelisted_field(): void
     {

tests/Fixtures/app/Http/Controllers/PostsController.php

@@ -37,6 +37,7 @@ public function filterableBy(): array
             'position',
             'publish_at',
             'user.name',
+            'user.roles.name',
             'meta.name',
             'meta.title',
             'meta->nested_field',

tests/Fixtures/app/Traits/AppliesDefaultOrder.php

@@ -11,7 +11,7 @@ protected static function boot()
         parent::boot();
         // Order by name ASC
         static::addGlobalScope('order', function (Builder $builder) {
-            $builder->orderBy('id', 'asc');
+            $builder->orderBy($builder->getModel()->getTable().'.id', 'asc');
         });
     }
-}
+}