Feature: Add size attribute to UploadFile

docs/requests.md

@@ -123,6 +123,7 @@ multidict, containing both file uploads and text input. File upload items are re
 * `content_type`: A `str` with the content type (MIME type / media type) (e.g. `image/jpeg`).
 * `file`: A <a href="https://docs.python.org/3/library/tempfile.html#tempfile.SpooledTemporaryFile" target="_blank">`SpooledTemporaryFile`</a> (a <a href="https://docs.python.org/3/glossary.html#term-file-like-object" target="_blank">file-like</a> object). This is the actual Python file that you can pass directly to other functions or libraries that expect a "file-like" object.
 * `headers`: A `Headers` object. Often this will only be the `Content-Type` header, but if additional headers were included in the multipart field they will be included here. Note that these headers have no relationship with the headers in `Request.headers`.
+* `size`: An `int` with uploaded file's size in bytes. This value is calculated from request's contents, making it better choice to find uploaded file's size than `Content-Length` header. `None` if not set.
 
 `UploadFile` has the following `async` methods. They all call the corresponding file methods underneath (using the internal `SpooledTemporaryFile`).
 

starlette/datastructures.py

@@ -438,11 +438,13 @@ def __init__(
         self,
         file: typing.BinaryIO,
         *,
+        size: typing.Optional[int] = None,
         filename: typing.Optional[str] = None,
         headers: "typing.Optional[Headers]" = None,
     ) -> None:
         self.filename = filename
         self.file = file
+        self.size = size
         self.headers = headers or Headers()
 
     @property
@@ -456,6 +458,9 @@ def _in_memory(self) -> bool:
         return not rolled_to_disk
 
     async def write(self, data: bytes) -> None:
+        if self.size is not None:
+            self.size += len(data)
+
         if self._in_memory:
             self.file.write(data)
         else:

starlette/formparsers.py

@@ -231,6 +231,7 @@ async def parse(self) -> FormData:
                         tempfile = SpooledTemporaryFile(max_size=self.max_file_size)
                         file = UploadFile(
                             file=tempfile,  # type: ignore[arg-type]
+                            size=0,
                             filename=filename,
                             headers=Headers(raw=item_headers),
                         )

tests/test_datastructures.py

@@ -293,10 +293,26 @@ def test_queryparams():
 async def test_upload_file_file_input():
     """Test passing file/stream into the UploadFile constructor"""
     stream = io.BytesIO(b"data")
+    file = UploadFile(filename="file", file=stream, size=4)
+    assert await file.read() == b"data"
+    assert file.size == 4
+    await file.write(b" and more data!")
+    assert await file.read() == b""
+    assert file.size == 19
+    await file.seek(0)
+    assert await file.read() == b"data and more data!"
+
+
+@pytest.mark.anyio
+async def test_upload_file_without_size():
+    """Test passing file/stream into the UploadFile constructor without size"""
+    stream = io.BytesIO(b"data")
     file = UploadFile(filename="file", file=stream)
     assert await file.read() == b"data"
+    assert file.size is None
     await file.write(b" and more data!")
     assert await file.read() == b""
+    assert file.size is None
     await file.seek(0)
     assert await file.read() == b"data and more data!"
 
@@ -310,22 +326,26 @@ async def test_uploadfile_rolling(max_size: int) -> None:
     stream: BinaryIO = SpooledTemporaryFile(  # type: ignore[assignment]
         max_size=max_size
     )
-    file = UploadFile(filename="file", file=stream)
+    file = UploadFile(filename="file", file=stream, size=0)
     assert await file.read() == b""
+    assert file.size == 0
     await file.write(b"data")
     assert await file.read() == b""
+    assert file.size == 4
     await file.seek(0)
     assert await file.read() == b"data"
     await file.write(b" more")
     assert await file.read() == b""
+    assert file.size == 9
     await file.seek(0)
     assert await file.read() == b"data more"
+    assert file.size == 9
     await file.close()
 
 
 def test_formdata():
     stream = io.BytesIO(b"data")
-    upload = UploadFile(filename="file", file=stream)
+    upload = UploadFile(filename="file", file=stream, size=4)
     form = FormData([("a", "123"), ("a", "456"), ("b", upload)])
     assert "a" in form
     assert "A" not in form

tests/test_formparsers.py

@@ -29,6 +29,7 @@ async def app(scope, receive, send):
             content = await value.read()
             output[key] = {
                 "filename": value.filename,
+                "size": value.size,
                 "content": content.decode(),
                 "content_type": value.content_type,
             }
@@ -51,6 +52,7 @@ async def multi_items_app(scope, receive, send):
             output[key].append(
                 {
                     "filename": value.filename,
+                    "size": value.size,
                     "content": content.decode(),
                     "content_type": value.content_type,
                 }
@@ -71,6 +73,7 @@ async def app_with_headers(scope, receive, send):
             content = await value.read()
             output[key] = {
                 "filename": value.filename,
+                "size": value.size,
                 "content": content.decode(),
                 "content_type": value.content_type,
                 "headers": list(value.headers.items()),
@@ -112,6 +115,7 @@ def test_multipart_request_files(tmpdir, test_client_factory):
         assert response.json() == {
             "test": {
                 "filename": "test.txt",
+                "size": 14,
                 "content": "<file content>",
                 "content_type": "text/plain",
             }
@@ -129,6 +133,7 @@ def test_multipart_request_files_with_content_type(tmpdir, test_client_factory):
         assert response.json() == {
             "test": {
                 "filename": "test.txt",
+                "size": 14,
                 "content": "<file content>",
                 "content_type": "text/plain",
             }
@@ -152,11 +157,13 @@ def test_multipart_request_multiple_files(tmpdir, test_client_factory):
         assert response.json() == {
             "test1": {
                 "filename": "test1.txt",
+                "size": 15,
                 "content": "<file1 content>",
                 "content_type": "text/plain",
             },
             "test2": {
                 "filename": "test2.txt",
+                "size": 15,
                 "content": "<file2 content>",
                 "content_type": "text/plain",
             },
@@ -185,6 +192,7 @@ def test_multipart_request_multiple_files_with_headers(tmpdir, test_client_facto
             "test1": "<file1 content>",
             "test2": {
                 "filename": "test2.txt",
+                "size": 15,
                 "content": "<file2 content>",
                 "content_type": "text/plain",
                 "headers": [
@@ -220,11 +228,13 @@ def test_multi_items(tmpdir, test_client_factory):
                 "abc",
                 {
                     "filename": "test1.txt",
+                    "size": 15,
                     "content": "<file1 content>",
                     "content_type": "text/plain",
                 },
                 {
                     "filename": "test2.txt",
+                    "size": 15,
                     "content": "<file2 content>",
                     "content_type": "text/plain",
                 },
@@ -261,6 +271,7 @@ def test_multipart_request_mixed_files_and_data(tmpdir, test_client_factory):
     assert response.json() == {
         "file": {
             "filename": "file.txt",
+            "size": 14,
             "content": "<file content>",
             "content_type": "text/plain",
         },
@@ -291,6 +302,7 @@ def test_multipart_request_with_charset_for_filename(tmpdir, test_client_factory
     assert response.json() == {
         "file": {
             "filename": "文書.txt",
+            "size": 14,
             "content": "<file content>",
             "content_type": "text/plain",
         }
@@ -318,6 +330,7 @@ def test_multipart_request_without_charset_for_filename(tmpdir, test_client_fact
     assert response.json() == {
         "file": {
             "filename": "画像.jpg",
+            "size": 14,
             "content": "<file content>",
             "content_type": "image/jpeg",
         }