This allows a frontmatter.yaml file to be included in a page folder

system/src/Grav/Common/Cache.php

@@ -263,6 +263,15 @@ public function getKey()
         return $this->key;
     }
 
+    /**
+     * Setter method to set key (Advanced)
+     */
+    public function setKey($key)
+    {
+        $this->key = $key;
+        $this->driver->setNamespace($this->key);
+    }
+
     /**
      * Helper method to clear all Grav caches
      *

system/src/Grav/Common/Page/Page.php

@@ -289,6 +289,16 @@ public function header($var = null)
                     $this->raw_content = $file->markdown();
                     $this->frontmatter = $file->frontmatter();
                     $this->header = (object)$file->header();
+
+                    // If there's a `frontmatter.yaml` file merge that in with the page header
+                    // note page's own frontmatter has precedence and will overwrite any defaults
+                    if (!Utils::isAdminPlugin()) {
+                        $frontmatter_file = $this->path . '/' . $this->folder . '/frontmatter.yaml';
+                        if (file_exists($frontmatter_file)) {
+                            $frontmatter_data = (array)Yaml::parse(file_get_contents($frontmatter_file));
+                            $this->header = (object)array_replace_recursive($frontmatter_data, (array)$this->header);
+                        }
+                    }
                 } catch (ParseException $e) {
                     $file->raw(Grav::instance()['language']->translate([
                         'FRONTMATTER_ERROR_PAGE',

system/src/Grav/Common/Plugin.php

@@ -101,11 +101,7 @@ public function config()
      */
     public function isAdmin()
     {
-        if (isset($this->grav['admin'])) {
-            return true;
-        }
-
-        return false;
+        return Utils::isAdminPlugin();
     }
 
     /**

system/src/Grav/Common/Utils.php

@@ -622,4 +622,18 @@ public static function verifyNonce($nonce, $action)
         //Invalid nonce
         return false;
     }
+
+    /**
+     * Simple helper method to get whether or not the admin plugin is active
+     *
+     * @return bool
+     */
+    public static function isAdminPlugin()
+    {
+        if (isset(Grav::instance()['admin'])) {
+            return true;
+        }
+
+        return false;
+    }
 }