new: [paramhandler] component added

- centralised handling of all things related to request parameter parsing

app/src/Controller/Component/ParamHandlerComponent.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace App\Controller\Component;
+
+use Cake\Controller\Component;
+use Cake\Core\Configure;
+
+class ParamHandlerComponent extends Component
+{
+    public function initialize(array $config): void
+    {
+        $this->request = $config['request'];
+    }
+
+    /*
+     *  Harvest parameters form a request
+     *
+     *  Requires the request object and a list of keys to filter as input
+     *  Order of precedence:
+     *  ordered uri components (/foo/bar/baz) > query strings (?foo=bar) > posted data (json body {"foo": "bar"})
+     */
+    public function harvestParams(array $filterList): array
+    {
+        $parsedParams = array();
+        foreach ($filterList as $k => $filter) {
+            if (isset($this->request->getAttribute('params')['pass'][$k])) {
+                $parsedParams[$filter] = $this->request->getAttribute('params')['pass'][$k];
+                continue;
+            }
+            if (($this->request->getQuery($filter)) !== null) {
+                $parsedParams[$filter] = $this->request->getQuery($filter);
+                continue;
+            }
+            if (($this->request->is('post') || $this->request->is('put')) && $this->request->getData($filter) !== null) {
+                $parsedParams[$filter] = $this->request->getData($filter);
+            }
+        }
+        return $parsedParams;
+    }
+
+    public function isRest()
+    {
+        // This method is surprisingly slow and called many times for one request, so it make sense to cache the result.
+        if ($this->isRest !== null) {
+            return $this->isRest;
+        }
+        if ($this->request->is('json')) {
+            if (!empty($this->request->input()) && empty($this->request->input('json_decode'))) {
+                throw new MethodNotAllowedException('Invalid JSON input. Make sure that the JSON input is a correctly formatted JSON string. This request has been blocked to avoid an unfiltered request.');
+            }
+            $this->isRest = true;
+            return true;
+        } else {
+            $this->isRest = false;
+            return false;
+        }
+    }
+
+    public function isJson($data)
+    {
+        return (json_decode($data) != null) ? true : false;
+    }
+}