add ability to filter by nested relation scopes

src/Filters/FiltersScope.php

@@ -14,11 +14,21 @@ class FiltersScope implements Filter
 {
     public function __invoke(Builder $query, $values, string $property): Builder
     {
-        $scope = Str::camel($property);
+        $propertyParts = Str::of($property)->explode('.');
+
+        $scope = Str::camel($propertyParts->pop());
 
         $values = array_values(Arr::wrap($values));
         $values = $this->resolveParameters($query, $values, $scope);
 
+        $relation = $propertyParts->implode('.');
+
+        if ($relation) {
+            return $query->whereHas($relation, function (Builder $query) use ($scope, $values) {
+                return $query->$scope(...$values);
+            });
+        }
+
         return $query->$scope(...$values);
     }
 

tests/FilterTest.php

@@ -200,6 +200,21 @@ public function it_can_filter_results_by_scope()
         $this->assertCount(1, $modelsResult);
     }
 
+    /** @test */
+    public function it_can_filter_results_by_nested_relation_scope()
+    {
+        $testModel = TestModel::create(['name' => 'John Testing Doe']);
+
+        $testModel->relatedModels()->create(['name' => 'John\'s Post']);
+
+        $modelsResult = $this
+            ->createQueryFromFilterRequest(['relatedModels.named' => 'John\'s Post'])
+            ->allowedFilters(AllowedFilter::scope('relatedModels.named'))
+            ->get();
+
+        $this->assertCount(1, $modelsResult);
+    }
+
     /** @test */
     public function it_can_filter_results_by_type_hinted_scope()
     {

tests/TestClasses/Models/RelatedModel.php

@@ -2,6 +2,7 @@
 
 namespace Spatie\QueryBuilder\Tests\TestClasses\Models;
 
+use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
@@ -21,4 +22,9 @@ public function nestedRelatedModels(): HasMany
     {
         return $this->hasMany(NestedRelatedModel::class);
     }
+
+    public function scopeNamed(Builder $query, string $name): Builder
+    {
+        return $query->where('name', $name);
+    }
 }