fix empty return

src/JSON.php

@@ -291,7 +291,7 @@ public function fillAtOnce(callable $fillAtOnceCallback = null): self
                 ? $fillAtOnceCallback($request, $requestValues, $model, $attribute, $requestAttribute)
                 : $requestValues;
 
-            if ($this->nullable && $this->isNullValue($value)) {
+            if (!$this->nullable && $this->isNullValue($value)) {
                 return;
             }
 
@@ -323,7 +323,7 @@ protected function getRequestValues(NovaRequest $request, Model $model): array
                 data_set($carry, $path, $item);
 
                 return $carry;
-            }, [])[$this->attribute];
+            }, [$this->attribute => []])[$this->attribute];
     }
 
     /**

tests/JSONTest.php

@@ -148,6 +148,21 @@ public function it_respects_the_fill_all_values_at_once_callback_and_individual_
         $this->assertEquals(['nested' => ['street' => 'some-val Foo', 'city' => 'other-val']], $user->address);
     }
 
+    /** @test */
+    public function it_does_not_store_values_for_fill_once_if_fields_are_not_nullable_and_nothing_is_returned_from_callback()
+    {
+        $user = new User(['address' => ['street' => '', 'city' => '']]);
+        $json = JSON::make('Address', 'address', [
+            Text::make('Street'),
+            Text::make('City'),
+        ])->nullable(false)->fillAtOnce(fn ($request, $requestValues) => null);
+
+        $request = new NovaRequest(['address->street' => 'some-val', 'address->city' => 'other-val', 'nonjson' => 'foo']);
+
+        collect($json->data)->last()->fillInto($request, $user, 'address');
+        $this->assertEquals(['street' => '', 'city' => ''], $user->address);
+    }
+
     /** @test */
     public function it_allows_storing_nullable_values()
     {