Expanded API code, wrote a bunch new transformers as well.

app/Api/V1/Controllers/Controller.php

@@ -22,12 +22,15 @@ declare(strict_types=1);
 
 namespace FireflyIII\Api\V1\Controllers;
 
+use Carbon\Carbon;
+use Carbon\Exceptions\InvalidDateException;
 use FireflyConfig;
 use FireflyIII\Exceptions\FireflyException;
 use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
 use Illuminate\Foundation\Bus\DispatchesJobs;
 use Illuminate\Foundation\Validation\ValidatesRequests;
 use Illuminate\Routing\Controller as BaseController;
+use Symfony\Component\HttpFoundation\ParameterBag;
 
 /**
  * Class Controller.
@@ -36,6 +39,9 @@ class Controller extends BaseController
 {
     use AuthorizesRequests, DispatchesJobs, ValidatesRequests;
 
+    /** @var ParameterBag */
+    protected $parameters;
+
     /**
      * Controller constructor.
      *
@@ -50,5 +56,49 @@ class Controller extends BaseController
         if (true === $isDemoSite) {
             throw new FireflyException('The API is not available on the demo site.');
         }
+
+        // get global parameters
+        $this->parameters = $this->getParameters();
+    }
+
+    /**
+     * @return ParameterBag
+     */
+    private function getParameters(): ParameterBag
+    {
+        $bag  = new ParameterBag;
+        $page = (int)request()->get('page');
+        if ($page === 0) {
+            $page = 1;
+        }
+        $bag->set('page', $page);
+
+        $start     = request()->get('start');
+        $startDate = null;
+        if (!is_null($start)) {
+            try {
+                $startDate = new Carbon($start);
+            } catch (InvalidDateException $e) {
+                // don't care
+            }
+        }
+        $bag->set('start', $startDate);
+
+        $end     = request()->get('end');
+        $endDate = null;
+        if (!is_null($end)) {
+            try {
+                $endDate = new Carbon($end);
+            } catch (InvalidDateException $e) {
+                // don't care
+            }
+        }
+        $bag->set('end', $endDate);
+
+        $type = request()->get('type') ?? 'all';
+        $bag->set('type', $type);
+
+        return $bag;
+
     }
 }