Fix Content-Lenght calculation of unicode string

httpx/_multipart.py

@@ -2,6 +2,7 @@
 import os
 import typing
 from pathlib import Path
+from typing import IO, Union
 
 from ._types import FileContent, FileTypes, RequestFiles
 from ._utils import (
@@ -40,11 +41,7 @@ def render_headers(self) -> bytes:
 
     def render_data(self) -> bytes:
         if not hasattr(self, "_data"):
-            self._data = (
-                self.value
-                if isinstance(self.value, bytes)
-                else self.value.encode("utf-8")
-            )
+            self._data = to_bytes(self.value)
 
         return self._data
 
@@ -74,20 +71,22 @@ def __init__(self, name: str, value: FileTypes) -> None:
             except ValueError:
                 filename, fileobj = value  # type: ignore
                 content_type = guess_content_type(filename)
+            if isinstance(fileobj, str):
+                fileobj = to_bytes(fileobj)
         else:
             filename = Path(str(getattr(value, "name", "upload"))).name
-            fileobj = value
+            fileobj = typing.cast(Union[IO[bytes], IO[str]], value)
             content_type = guess_content_type(filename)
 
         self.filename = filename
-        self.file = fileobj
+        self.file: Union[IO[bytes], IO[str], bytes] = fileobj
         self.content_type = content_type
         self._consumed = False
 
     def get_length(self) -> int:
         headers = self.render_headers()
 
-        if isinstance(self.file, (str, bytes)):
+        if isinstance(self.file, bytes):
             return len(headers) + len(self.file)
 
         # Let's do our best not to read `file` into memory.
@@ -119,8 +118,8 @@ def render_headers(self) -> bytes:
         return self._headers
 
     def render_data(self) -> typing.Iterator[bytes]:
-        if isinstance(self.file, (str, bytes)):
-            yield to_bytes(self.file)
+        if isinstance(self.file, bytes):
+            yield self.file
             return
 
         if hasattr(self, "_data"):

tests/test_multipart.py

@@ -8,6 +8,7 @@
 
 import httpx
 from httpx._content import encode_request
+from httpx._types import RequestFiles
 from httpx._utils import format_form_param
 
 
@@ -105,7 +106,10 @@ def test_multipart_encode(tmp_path: typing.Any) -> None:
         "c": ["11", "22", "33"],
         "d": "",
     }
-    files = {"file": ("name.txt", open(path, "rb"))}
+    files: RequestFiles = {
+        "file": ("name.txt", open(path, "rb")),
+        "file2": ("file2.txt", "<únicode string>"),
+    }
 
     with mock.patch("os.urandom", return_value=os.urandom(16)):
         boundary = os.urandom(16).hex()
@@ -123,8 +127,11 @@ def test_multipart_encode(tmp_path: typing.Any) -> None:
             '--{0}\r\nContent-Disposition: form-data; name="file";'
             ' filename="name.txt"\r\n'
             "Content-Type: text/plain\r\n\r\n<file content>\r\n"
+            '--{0}\r\nContent-Disposition: form-data; name="file2";'
+            ' filename="file2.txt"\r\n'
+            "Content-Type: text/plain\r\n\r\n<únicode string>\r\n"
             "--{0}--\r\n"
-            "".format(boundary).encode("ascii")
+            "".format(boundary).encode("utf-8")
         )
         assert headers == {
             "Content-Type": f"multipart/form-data; boundary={boundary}",