fix(multipart): use field names in request (#3135)

Co-authored-by: Aaron Pham <29749331+aarnphm@users.noreply.github.com>

src/bentoml/_internal/io_descriptors/multipart.py

@@ -238,13 +238,21 @@ async def from_http_request(self, request: Request) -> dict[str, t.Any]:
                 f"{self.__class__.__name__} only accepts `multipart/form-data` as Content-Type header, got {ctype} instead."
             ) from None
 
-        to_populate = zip(
-            self._inputs.values(), (await populate_multipart_requests(request)).values()
-        )
-        reqs = await asyncio.gather(
-            *tuple(io_.from_http_request(req) for io_, req in to_populate)
-        )
-        return dict(zip(self._inputs, reqs))
+        form_values = await populate_multipart_requests(request)
+
+        res = {}
+        for field, descriptor in self._inputs.items():
+            if field not in form_values:
+                break
+            res[field] = descriptor.from_http_request(form_values[field])
+        else:  # NOTE: This is similar to goto, when there is no break.
+            to_populate = zip(self._inputs.values(), form_values.values())
+            reqs = await asyncio.gather(
+                *tuple(io_.from_http_request(req) for io_, req in to_populate)
+            )
+            res = dict(zip(self._inputs, reqs))
+
+        return res
 
     async def to_http_response(
         self, obj: dict[str, t.Any], ctx: Context | None = None

tests/e2e/bento_server_http/service.py

@@ -124,7 +124,19 @@ async def echo_image(f: PILImage) -> NDArray[t.Any]:
     input=Multipart(original=Image(), compared=Image()),
     output=Multipart(img1=Image(), img2=Image()),
 )
-async def predict_multi_images(original: dict[str, Image], compared: dict[str, Image]):
+async def predict_multi_images(original: Image, compared: Image):
+    output_array = await py_model.predict_multi_ndarray.async_run(
+        np.array(original), np.array(compared)
+    )
+    img = fromarray(output_array)
+    return dict(img1=img, img2=img)
+
+
+@svc.api(
+    input=Multipart(original=Image(), compared=Image()),
+    output=Multipart(img1=Image(), img2=Image()),
+)
+async def predict_different_args(compared: Image, original: Image):
     output_array = await py_model.predict_multi_ndarray.async_run(
         np.array(original), np.array(compared)
     )

tests/e2e/bento_server_http/tests/test_io.py

@@ -222,22 +222,38 @@ async def test_image(host: str, img_file: str):
     )
 
 
+@pytest.fixture(name="img_form_data")
+def fixture_img_form_data(img_file: str):
+    with open(img_file, "rb") as f1, open(img_file, "rb") as f2:
+        form = aiohttp.FormData()
+        form.add_field("original", f1.read(), content_type="image/bmp")
+        form.add_field("compared", f2.read(), content_type="image/bmp")
+    yield form
+
+
 @pytest.mark.asyncio
-async def test_multipart_image_io(host: str, img_file: str):
+async def test_multipart_image_io(host: str, img_form_data: aiohttp.FormData):
     from starlette.datastructures import UploadFile
 
-    with open(img_file, "rb") as f1:
-        with open(img_file, "rb") as f2:
-            form = aiohttp.FormData()
-            form.add_field("original", f1.read(), content_type="image/bmp")
-            form.add_field("compared", f2.read(), content_type="image/bmp")
-
     _, headers, body = await async_request(
-        "POST", f"http://{host}/predict_multi_images", data=form, assert_status=200
+        "POST",
+        f"http://{host}/predict_multi_images",
+        data=img_form_data,
+        assert_status=200,
     )
 
     form = await parse_multipart_form(headers=headers, body=body)
     for _, v in form.items():
         assert isinstance(v, UploadFile)
         img = PILImage.open(v.file)
         assert np.array(img).shape == (10, 10, 3)
+
+
+@pytest.mark.asyncio
+async def test_multipart_image_io(host: str, img_form_data: aiohttp.FormData):
+    await async_request(
+        "POST",
+        f"http://{host}/predict_different_args",
+        data=img_form_data,
+        assert_status=200,
+    )