add a way to limit query server side

Author: pxpm

src/app/Http/Controllers/Operations/ListOperation.php

@@ -79,6 +79,11 @@ public function search()
         $length = (int) request()->input('length');
         $search = request()->input('search');
 
+        // we get the max length from the page length menu possibilities
+        $maxLength = $this->crud->maxPageLength();
+
+        $length = $maxLength === -1 ? $length : ($length > $maxLength ? $maxLength : $length);
+
         // if a search term was present
         if ($search && $search['value'] ?? false) {
             // filter the results accordingly

src/app/Library/CrudPanel/Traits/Read.php

@@ -218,6 +218,21 @@ public function getDefaultPageLength()
         return $this->getOperationSetting('defaultPageLength') ?? config('backpack.crud.operations.list.defaultPageLength') ?? 25;
     }
 
+    /**
+     * Get the higher limit from the page length menu.
+     * -1 means "All" so if present it means no limit.
+     */
+    public function maxPageLength(): int
+    {
+        $pageLengthMenu = $this->getPageLengthMenu();
+
+        if(in_array(-1, $pageLengthMenu[0])) {
+            return -1;
+        }
+
+        return (int)max($pageLengthMenu[0]);
+    }
+
     /**
      * If a custom page length was specified as default, make sure it
      * also show up in the page length menu.