I have a simple form, with the Joomla User registration plugin enabled.

This works all fine - when a user submits the form, the user is created in Joomla.

But i need to store information in another database table as well. (ex #__shop_users)
I have tried the mapping-tool in RSForm Pro, and this works fine too!

Now i need to store the Joomla UserID (the index key of #__users for the new user.
The id in #__users needs to be stored in #__shop_users as well for the user created.

But how to i get this id?

Hope that somone can help me with this.

Create a hidden field and in the Default Value field insert this code:

//<code>
$user = JFactory::getUser();
return $user->get('id');
//</code>

Next step would be to map the result in the desired table.