Add option to keep the same method for 301/302 redirects

RFC hasn't been clear enough about the expected behavior for 301 and
302 response. While it's (unfortunately) common for browsers to switch
the original http method to GET when following redirects, some server
applications expects the "legacy" behavior which keeps the same method
over redirects.

Add new option to clients to select the behavior.

Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

Author: kajinamit

httpx/_client.py

@@ -196,6 +196,7 @@ def __init__(
         timeout: TimeoutTypes = DEFAULT_TIMEOUT_CONFIG,
         follow_redirects: bool = False,
         max_redirects: int = DEFAULT_MAX_REDIRECTS,
+        keep_method_for_redirects: bool = False,
         event_hooks: None | (typing.Mapping[str, list[EventHook]]) = None,
         base_url: URL | str = "",
         trust_env: bool = True,
@@ -212,6 +213,7 @@ def __init__(
         self._timeout = Timeout(timeout)
         self.follow_redirects = follow_redirects
         self.max_redirects = max_redirects
+        self.keep_method_for_redirects = keep_method_for_redirects
         self._event_hooks = {
             "request": list(event_hooks.get("request", [])),
             "response": list(event_hooks.get("response", [])),
@@ -502,6 +504,9 @@ def _redirect_method(self, request: Request, response: Response) -> str:
         if response.status_code == codes.SEE_OTHER and method != "HEAD":
             method = "GET"
 
+        if self.keep_method_for_redirects:
+            return method
+
         # Do what the browsers do, despite standards...
         # Turn 302s into GETs.
         if response.status_code == codes.FOUND and method != "HEAD":
@@ -622,9 +627,13 @@ class Client(BaseClient):
     * **proxy** - *(optional)* A proxy URL where all the traffic should be routed.
     * **timeout** - *(optional)* The timeout configuration to use when sending
     requests.
+    * **follow_redirects** - *(optional)* Follow redirects and send a new
+    * request to the redirected url automatically.
     * **limits** - *(optional)* The limits configuration to use.
     * **max_redirects** - *(optional)* The maximum number of redirect responses
     that should be followed.
+    * **keep_method_for_redirects* - *(optional)* Keep the original HTTP method
+    when following redirects. This is effective only for 301 and 302 .
     * **base_url** - *(optional)* A URL to use as the base when building
     request URLs.
     * **transport** - *(optional)* A transport class to use for sending requests
@@ -654,6 +663,7 @@ def __init__(
         follow_redirects: bool = False,
         limits: Limits = DEFAULT_LIMITS,
         max_redirects: int = DEFAULT_MAX_REDIRECTS,
+        keep_method_for_redirects: bool = False,
         event_hooks: None | (typing.Mapping[str, list[EventHook]]) = None,
         base_url: URL | str = "",
         transport: BaseTransport | None = None,
@@ -667,6 +677,7 @@ def __init__(
             timeout=timeout,
             follow_redirects=follow_redirects,
             max_redirects=max_redirects,
+            keep_method_for_redirects=keep_method_for_redirects,
             event_hooks=event_hooks,
             base_url=base_url,
             trust_env=trust_env,
@@ -1336,9 +1347,13 @@ class AsyncClient(BaseClient):
     * **proxy** - *(optional)* A proxy URL where all the traffic should be routed.
     * **timeout** - *(optional)* The timeout configuration to use when sending
     requests.
+    * **follow_redirects** - *(optional)* Follow redirects and send a new
+    * request to the redirected url automatically.
     * **limits** - *(optional)* The limits configuration to use.
     * **max_redirects** - *(optional)* The maximum number of redirect responses
     that should be followed.
+    * **keep_method_for_redirects* - *(optional)* Keep the original HTTP method
+    when following redirects. This is effective only for 301 and 302 .
     * **base_url** - *(optional)* A URL to use as the base when building
     request URLs.
     * **transport** - *(optional)* A transport class to use for sending requests
@@ -1367,6 +1382,7 @@ def __init__(
         follow_redirects: bool = False,
         limits: Limits = DEFAULT_LIMITS,
         max_redirects: int = DEFAULT_MAX_REDIRECTS,
+        keep_method_for_redirects: bool = False,
         event_hooks: None | (typing.Mapping[str, list[EventHook]]) = None,
         base_url: URL | str = "",
         transport: AsyncBaseTransport | None = None,
@@ -1381,6 +1397,7 @@ def __init__(
             timeout=timeout,
             follow_redirects=follow_redirects,
             max_redirects=max_redirects,
+            keep_method_for_redirects=keep_method_for_redirects,
             event_hooks=event_hooks,
             base_url=base_url,
             trust_env=trust_env,

tests/client/test_redirects.py

@@ -118,6 +118,18 @@ def test_redirect_301():
     response = client.post("https://example.org/redirect_301", follow_redirects=True)
     assert response.status_code == httpx.codes.OK
     assert response.url == "https://example.org/"
+    assert response.request.method == "GET"
+    assert len(response.history) == 1
+
+
+def test_redirect_301_keep_method():
+    client = httpx.Client(
+        transport=httpx.MockTransport(redirects), keep_method_for_redirects=True
+    )
+    response = client.post("https://example.org/redirect_301", follow_redirects=True)
+    assert response.status_code == httpx.codes.OK
+    assert response.url == "https://example.org/"
+    assert response.request.method == "POST"
     assert len(response.history) == 1
 
 
@@ -126,6 +138,18 @@ def test_redirect_302():
     response = client.post("https://example.org/redirect_302", follow_redirects=True)
     assert response.status_code == httpx.codes.OK
     assert response.url == "https://example.org/"
+    assert response.request.method == "GET"
+    assert len(response.history) == 1
+
+
+def test_redirect_302_keep_method():
+    client = httpx.Client(
+        transport=httpx.MockTransport(redirects), keep_method_for_redirects=True
+    )
+    response = client.post("https://example.org/redirect_302", follow_redirects=True)
+    assert response.status_code == httpx.codes.OK
+    assert response.url == "https://example.org/"
+    assert response.request.method == "POST"
     assert len(response.history) == 1
 
 
@@ -134,6 +158,18 @@ def test_redirect_303():
     response = client.get("https://example.org/redirect_303", follow_redirects=True)
     assert response.status_code == httpx.codes.OK
     assert response.url == "https://example.org/"
+    assert response.request.method == "GET"
+    assert len(response.history) == 1
+
+
+def test_redirect_303_keep_method():
+    client = httpx.Client(
+        transport=httpx.MockTransport(redirects), keep_method_for_redirects=True
+    )
+    response = client.get("https://example.org/redirect_303", follow_redirects=True)
+    assert response.status_code == httpx.codes.OK
+    assert response.url == "https://example.org/"
+    assert response.request.method == "GET"
     assert len(response.history) == 1