Fix sanic adapter casting files to io.BytesIO

RELEASE.md

@@ -0,0 +1,4 @@
+Release type: patch
+
+Fix bug where files would be converted into io.BytesIO when using the sanic GraphQLView
+instead of using the sanic File type

strawberry/sanic/utils.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from io import BytesIO
 from typing import TYPE_CHECKING, Any, Optional, Union, cast
 
 from sanic.request import File
@@ -10,7 +9,7 @@
 
 
 def convert_request_to_files_dict(request: Request) -> dict[str, Any]:
-    """Converts the request.files dictionary to a dictionary of BytesIO objects.
+    """Converts the request.files dictionary to a dictionary of sanic Request objects.
 
     `request.files` has the following format, even if only a single file is uploaded:
 
@@ -29,12 +28,12 @@ def convert_request_to_files_dict(request: Request) -> dict[str, Any]:
     if not request_files:
         return {}
 
-    files_dict: dict[str, Union[BytesIO, list[BytesIO]]] = {}
+    files_dict: dict[str, Union[File, list[File]]] = {}
 
     for field_name, file_list in request_files.items():
         assert len(file_list) == 1
 
-        files_dict[field_name] = BytesIO(file_list[0].body)
+        files_dict[field_name] = file_list[0]
 
     return files_dict
 

tests/sanic/test_file_upload.py

@@ -0,0 +1,94 @@
+from io import BytesIO
+from typing import cast
+
+import pytest
+from sanic_testing.testing import SanicTestClient
+
+import strawberry
+from sanic import Sanic
+from sanic.request import File
+from strawberry.file_uploads import Upload
+from strawberry.sanic import utils
+from strawberry.sanic.views import GraphQLView
+
+
+@strawberry.type
+class Query:
+    @strawberry.field
+    def index(self) -> str:
+        return "Hello there"
+
+
+@strawberry.type
+class Mutation:
+    @strawberry.mutation
+    def file_upload(self, file: Upload) -> str:
+        return cast(File, file).name
+
+
+@pytest.fixture
+def app():
+    sanic_app = Sanic("sanic_testing")
+
+    sanic_app.add_route(
+        GraphQLView.as_view(
+            schema=strawberry.Schema(query=Query, mutation=Mutation),
+            multipart_uploads_enabled=True,
+        ),
+        "/graphql",
+    )
+
+    return sanic_app
+
+
+def test_file_cast(app: Sanic):
+    """Tests that the list of files in a sanic Request gets correctly turned into a dictionary"""
+    file_name = "test.txt"
+
+    file_content = b"Hello, there!."
+    in_memory_file = BytesIO(file_content)
+    in_memory_file.name = file_name
+
+    form_data = {
+        "operations": '{ "query": "mutation($file: Upload!){ fileUpload(file: $file) }", "variables": { "file": null } }',
+        "map": '{ "file": ["variables.file"] }',
+    }
+
+    files = {
+        "file": in_memory_file,
+    }
+
+    request, _ = cast(SanicTestClient, app.test_client).post(
+        "/graphql", data=form_data, files=files
+    )
+
+    files = utils.convert_request_to_files_dict(request)  # type: ignore
+    file = files["file"]
+
+    assert isinstance(file, File)
+    assert file.name == file_name
+    assert file.body == file_content
+
+
+def test_endpoint(app: Sanic):
+    """Tests that the graphql api correctly handles file upload and processing"""
+    file_name = "test.txt"
+
+    file_content = b"Hello, there!"
+    in_memory_file = BytesIO(file_content)
+    in_memory_file.name = file_name
+
+    form_data = {
+        "operations": '{ "query": "mutation($file: Upload!){ fileUpload(file: $file) }", "variables": { "file": null } }',
+        "map": '{ "file": ["variables.file"] }',
+    }
+
+    files = {
+        "file": in_memory_file,
+    }
+
+    _, response = cast(SanicTestClient, app.test_client).post(
+        "/graphql", data=form_data, files=files
+    )
+
+    assert response.json["data"]["fileUpload"] == file_name  # type: ignore