From 7827b1b41d36dcf297c8bf8a3e8b74d5368339a2 Mon Sep 17 00:00:00 2001
From: Adam Hopkins <adam@amhopkins.com>
Date: Wed, 10 Aug 2022 21:12:09 +0300
Subject: [PATCH] Add Request properties for HTTP method info (#2516)

---
 sanic/constants.py    |  9 ++++++++
 sanic/request.py      | 34 ++++++++++++++++++++++++++++-
 tests/test_request.py | 51 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/sanic/constants.py b/sanic/constants.py
index 52ec50ef..988d8bae 100644
--- a/sanic/constants.py
+++ b/sanic/constants.py
@@ -34,6 +34,15 @@ class LocalCertCreator(str, Enum):
 
 
 HTTP_METHODS = tuple(HTTPMethod.__members__.values())
+SAFE_HTTP_METHODS = (HTTPMethod.GET, HTTPMethod.HEAD, HTTPMethod.OPTIONS)
+IDEMPOTENT_HTTP_METHODS = (
+    HTTPMethod.GET,
+    HTTPMethod.HEAD,
+    HTTPMethod.PUT,
+    HTTPMethod.DELETE,
+    HTTPMethod.OPTIONS,
+)
+CACHEABLE_HTTP_METHODS = (HTTPMethod.GET, HTTPMethod.HEAD)
 DEFAULT_HTTP_CONTENT_TYPE = "application/octet-stream"
 DEFAULT_LOCAL_TLS_KEY = "key.pem"
 DEFAULT_LOCAL_TLS_CERT = "cert.pem"
diff --git a/sanic/request.py b/sanic/request.py
index 927c124a..0a8ca59e 100644
--- a/sanic/request.py
+++ b/sanic/request.py
@@ -38,7 +38,12 @@ from httptools import parse_url
 from httptools.parser.errors import HttpParserInvalidURLError
 
 from sanic.compat import CancelledErrors, Header
-from sanic.constants import DEFAULT_HTTP_CONTENT_TYPE
+from sanic.constants import (
+    CACHEABLE_HTTP_METHODS,
+    DEFAULT_HTTP_CONTENT_TYPE,
+    IDEMPOTENT_HTTP_METHODS,
+    SAFE_HTTP_METHODS,
+)
 from sanic.exceptions import BadRequest, BadURL, ServerError
 from sanic.headers import (
     AcceptContainer,
@@ -975,6 +980,33 @@ class Request:
 
         return self.transport.scope
 
+    @property
+    def is_safe(self) -> bool:
+        """
+        :return: Whether the HTTP method is safe.
+            See https://datatracker.ietf.org/doc/html/rfc7231#section-4.2.1
+        :rtype: bool
+        """
+        return self.method in SAFE_HTTP_METHODS
+
+    @property
+    def is_idempotent(self) -> bool:
+        """
+        :return: Whether the HTTP method is iempotent.
+            See https://datatracker.ietf.org/doc/html/rfc7231#section-4.2.2
+        :rtype: bool
+        """
+        return self.method in IDEMPOTENT_HTTP_METHODS
+
+    @property
+    def is_cacheable(self) -> bool:
+        """
+        :return: Whether the HTTP method is cacheable.
+            See https://datatracker.ietf.org/doc/html/rfc7231#section-4.2.3
+        :rtype: bool
+        """
+        return self.method in CACHEABLE_HTTP_METHODS
+
 
 class File(NamedTuple):
     """
diff --git a/tests/test_request.py b/tests/test_request.py
index e01cc1e7..3a4132ae 100644
--- a/tests/test_request.py
+++ b/tests/test_request.py
@@ -243,3 +243,54 @@ def test_request_stream_id(app):
 
     _, resp = app.test_client.get("/")
     assert resp.text == "Stream ID is only a property of a HTTP/3 request"
+
+
+@pytest.mark.parametrize(
+    "method,safe",
+    (
+        ("DELETE", False),
+        ("GET", True),
+        ("HEAD", True),
+        ("OPTIONS", True),
+        ("PATCH", False),
+        ("POST", False),
+        ("PUT", False),
+    ),
+)
+def test_request_safe(method, safe):
+    request = Request(b"/", {}, None, method, None, None)
+    assert request.is_safe is safe
+
+
+@pytest.mark.parametrize(
+    "method,idempotent",
+    (
+        ("DELETE", True),
+        ("GET", True),
+        ("HEAD", True),
+        ("OPTIONS", True),
+        ("PATCH", False),
+        ("POST", False),
+        ("PUT", True),
+    ),
+)
+def test_request_idempotent(method, idempotent):
+    request = Request(b"/", {}, None, method, None, None)
+    assert request.is_idempotent is idempotent
+
+
+@pytest.mark.parametrize(
+    "method,cacheable",
+    (
+        ("DELETE", False),
+        ("GET", True),
+        ("HEAD", True),
+        ("OPTIONS", False),
+        ("PATCH", False),
+        ("POST", False),
+        ("PUT", False),
+    ),
+)
+def test_request_cacheable(method, cacheable):
+    request = Request(b"/", {}, None, method, None, None)
+    assert request.is_cacheable is cacheable