feat: HTTP method-aware web page caching

system/Cache/ResponseCache.php

@@ -86,7 +86,7 @@ public function generateCacheKey($request): string
             ? $uri->getQuery(is_array($this->cacheQueryString) ? ['only' => $this->cacheQueryString] : [])
             : '';
 
-        return md5((string) $uri->setFragment('')->setQuery($query));
+        return md5($request->getMethod() . ':' . $uri->setFragment('')->setQuery($query));
     }
 
     /**

system/HTTP/Method.php

@@ -19,57 +19,81 @@
 class Method
 {
     /**
+     * Safe: No
+     * Idempotent: No
+     * Cacheable: No
+     *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/CONNECT
      */
     public const CONNECT = 'CONNECT';
 
     /**
-     * Idempotent
+     * Safe: No
+     * Idempotent: Yes
+     * Cacheable: No
      *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/DELETE
      */
     public const DELETE = 'DELETE';
 
     /**
-     * Safe, Idempotent, Cacheable
+     * Safe: Yes
+     * Idempotent: Yes
+     * Cacheable: Yes
      *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/GET
      */
     public const GET = 'GET';
 
     /**
-     * Safe, Idempotent, Cacheable
+     * Safe: Yes
+     * Idempotent: Yes
+     * Cacheable: Yes
      *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/HEAD
      */
     public const HEAD = 'HEAD';
 
     /**
-     * Safe, Idempotent
+     * Safe: Yes
+     * Idempotent: Yes
+     * Cacheable: No
      *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/OPTIONS
      */
     public const OPTIONS = 'OPTIONS';
 
     /**
+     * Safe: No
+     * Idempotent: No
+     * Cacheable: Only if freshness information is included
+     *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PATCH
      */
     public const PATCH = 'PATCH';
 
     /**
+     * Safe: No
+     * Idempotent: No
+     * Cacheable: Only if freshness information is included
+     *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST
      */
     public const POST = 'POST';
 
     /**
-     * Idempotent
+     * Safe: No
+     * Idempotent: Yes
+     * Cacheable: No
      *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PUT
      */
     public const PUT = 'PUT';
 
     /**
-     * Safe, Idempotent
+     * Safe: Yes
+     * Idempotent: Yes
+     * Cacheable: No
      *
      * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/TRACE
      */

tests/system/Cache/ResponseCacheTest.php

@@ -169,6 +169,26 @@ public function testCachePageIncomingRequestWithCacheQueryString()
         $this->assertNull($cachedResponse);
     }
 
+    public function testCachePageIncomingRequestWithHttpMethods()
+    {
+        $pageCache = $this->createResponseCache();
+
+        $request = $this->createIncomingRequest('foo/bar');
+
+        $response = new Response($this->appConfig);
+        $response->setBody('The response body.');
+
+        $return = $pageCache->make($request, $response);
+
+        $this->assertTrue($return);
+
+        // Check cache with a request with the same URI path and different HTTP method
+        $request        = $this->createIncomingRequest('foo/bar')->withMethod('POST');
+        $cachedResponse = $pageCache->get($request, new Response($this->appConfig));
+
+        $this->assertNull($cachedResponse);
+    }
+
     public function testCachePageCLIRequest()
     {
         $pageCache = $this->createResponseCache();

user_guide_src/source/changelogs/v4.5.0.rst

@@ -346,6 +346,9 @@ Others
   existing CSP directives. See :ref:`csp-clear-directives`.
 - **HTTP:** Added ``Message::addHeader()`` method to add another header with
   the same name. See :php:meth:`CodeIgniter\\HTTP\\Message::addHeader()`.
+- **Web Page Caching:** ``ResponseCache`` has been improved to include the request
+  HTTP method in the cache key. This means that the same URI will be cached separately
+  if the HTTP method is different.
 
 Message Changes
 ***************

user_guide_src/source/general/caching.rst

@@ -20,11 +20,17 @@ How Does Caching Work?
 ======================
 
 Caching can be enabled on a per-page basis, and you can set the length
-of time that a page should remain cached before being refreshed. When a
-page is loaded for the first time, the page will be cached using the
+of time that a page should remain cached before being refreshed.
+
+.. note:: Per-page means per URI. Since v4.5.0, the HTTP method of the
+    request is also taken into account. This means that the same URI will be
+    cached separately if the HTTP method is different.
+
+When a page is loaded for the first time, the page will be cached using the
 currently configured cache engine. On subsequent page loads, the cache
-will be retrieved and sent to the requesting user's browser. If it has
-expired, it will be deleted and refreshed before being sent to the
+will be retrieved and sent to the requesting user's browser.
+
+If it has expired, it will be deleted and refreshed before being sent to the
 browser.
 
 .. note:: The Benchmark tag is not cached so you can still view your page