I am trying to change the default value of the description field based on the category id (Action: Listing Submit).
I have found following starting point, however I always get a critical issue when trying to access the model as the listing is not created at this point (most likely?). How can I modify the code to get the category ids of submit listing form so we I can use it later on to modify the values.
This snippet looks good, but you need to modify it by adding the condition that the model is not null; the submit form already has a listing. Also, when checking categories, try just adding the default value.