Call com_ajax from module backend

Question

To create thumbnails & cache files, I have to access my already created Ajax Functions inside my helper.php file.

I'm already able to call the functions within the frontend (button that is visible when debug is active calls the js functions) -- all fine from frontend -- but if I add the same js into the backend I get the error:

The file at mod_modname/helper.php does not exist.

My request looks like this:

let data = {
        'moduleId': '{$moduleId}'
    };
let request = {
        'url' : '{$url}', // is JURI::current() //--> already tried without
        'option': 'com_ajax',
        'module': 'modname',
        'method': 'getImages',
        'data': str_data,
        'format': 'json'
    };

so JURI::current here is: mydomain.tld/administrator/index.php

The initial call that did not work is located in 'mod_mymodname/models/fields/myCustomfield.php' as follows:

protected function getInput()
    {
        $formData = json_decode($this->form->getData('jform'),'true');

        if(isset($formData['id'])) {
            $moduleId = $formData['id'];

            include JPATH_ROOT.'/modules/mod_modname/helper/buildCache.js.php';

            $doc = JFactory::getDocument();
            $doc->addScriptDeclaration($buildCacheActivation);
...

Keep in mind - all works from frontend, just from module backend (where I also want to be able to "create" the cache, I receive that error).

I think it could be something with the path / the different locations from where the script will be called?

Unfortunately, I did not find any solution for this issue in the guides.

Edit: Added Ajax Call URL Frontend:

url=http%3A%2F%2Flocalhost%2Fjoomla1%2Findex.php&option=com_ajax&module=modulename&method=getGalleries&data=%7B%22moduleId%22%3A%22110%22%7D&format=json

Backend:

url=http%3A%2F%2Flocalhost%2Fjoomla1%2Findex.php&option=com_ajax&module=modulename&method=getGalleries&data=%7B%22moduleId%22%3A%22110%22%7D&format=json

So its the same....

different are the "Request URL" which is as follows from backend: http://localhost/joomla1/administrator/index.php?option=com_modules&view=module&layout=edit&id=110

Answer 1

If you still want to use the frontend urls from backend, make sure to call the frontend site appropriately.

Your should use Juri::root() to get site url from administrator instead of Juri::base() or Juri::current().

Juri::root() --> http://mysite.local

Juri::base() --> http://mysite.local/administrator

Juri::current() --> http://mysite.local/administrator/index.php?option=some_component&view=some_view

Answer 2

I'm leaving this here for future readers:

The End-Solution after the analysis with Somy Ericsson was to create a second module. For the AJAX-Backend tasks i've packed my existing frontend module and this second one into a Package. The administrator module contains a helper file that response to the AJAX calls made from my frontend module's backend.

That was necessary because of the fact that the com_ajax is searching for the helper file via the JPATH_BASE constant.

in fact if called from frontend the path is: modules/mod_modname/helper.php

and from backend via customfield: administrator/modules/mod_modname/helper.php

because we cannot change where com_ajax searches for the helper-file the workaround with a second module was necessary.

thanks to Somy for pointing me into the right direction.