[PR #5393/c6eb5307 backport][3.8] Fix content-type on empty string. (#…

…6121)

* Fix content-type on empty string. (#5393)

Co-authored-by: Andrew Svetlov <[email protected]>
(cherry picked from commit c6eb530)

* fix

Co-authored-by: Sam Bull <[email protected]>
Co-authored-by: Andrew Svetlov <[email protected]>

CHANGES/5392.bugfix

@@ -0,0 +1 @@
+Set "text/plain" when data is an empty string in client requests.

aiohttp/client_reqrep.py

@@ -311,7 +311,7 @@ def __init__(
         self.update_proxy(proxy, proxy_auth, proxy_headers)
 
         self.update_body_from_data(data)
-        if data or self.method not in self.GET_METHODS:
+        if data is not None or self.method not in self.GET_METHODS:
             self.update_transfer_encoding()
         self.update_expect_continue(expect100)
         if traces is None:
@@ -449,7 +449,7 @@ def update_cookies(self, cookies: Optional[LooseCookies]) -> None:
 
     def update_content_encoding(self, data: Any) -> None:
         """Set request content encoding."""
-        if not data:
+        if data is None:
             return
 
         enc = self.headers.get(hdrs.CONTENT_ENCODING, "").lower()
@@ -499,7 +499,7 @@ def update_auth(self, auth: Optional[BasicAuth]) -> None:
         self.headers[hdrs.AUTHORIZATION] = auth.encode()
 
     def update_body_from_data(self, body: Any) -> None:
-        if not body:
+        if body is None:
             return
 
         # FormData

tests/test_client_functional.py

@@ -3007,3 +3007,22 @@ async def handler(request):
 
     async with await client.get("/", read_bufsize=4) as resp:
         assert resp.content.get_read_buffer_limits() == (4, 8)
+
+
+async def test_http_empty_data_text(aiohttp_client) -> None:
+    async def handler(request):
+        data = await request.read()
+        ret = "ok" if data == b"" else "fail"
+        resp = web.Response(text=ret)
+        resp.headers["Content-Type"] = request.headers["Content-Type"]
+        return resp
+
+    app = web.Application()
+    app.add_routes([web.post("/", handler)])
+
+    client = await aiohttp_client(app)
+
+    async with await client.post("/", data="") as resp:
+        assert resp.status == 200
+        assert await resp.text() == "ok"
+        assert resp.headers["Content-Type"] == "text/plain; charset=utf-8"