How does the "available for" of a "catalog item" work?

[Lisa71]

I see even the "available for" of the catalog item is empty, we still can access the catalog item. Why? 

Also, where to view the backend code for the catalog item access restriction?

[Brad Bowman]

Catalog Items are available to all users by default.  If criteria is added to the Available For or Not Available For Related Lists, that would make the Catalog Item available for or not available for only the users that meet the criteria.  User Criteria is stored on the user_criteria table and applied to catalog items via a many to many table sc_cat_item_user_criteria_mtom

[Lisa71]

Thanks.

1. So if the "available for" and "not available for" is empty, everyone can view the catalog items?

2. If one user criteria is added, then only that added user criteria can access it, right?

3. where to view the script code for limiting the catalog item access? 

[Eshwar Reddy]

@Lisa71 
1. If both "available for" and "not available for are empty, the catalog item is accessible to all users.

2. When you add a user criteria, only users who meet that criteria can access the catalog item. If multiple criteria are defined, a user must meet at least one of them to gain access.

3. User Criteria is stored on the user_criteria table. You can also look in the "Script" tab of the catalog item to see any associated scripts that may apply.

Note: The association between catalog items and user criteria is handled through the many-to-many table called sc_cat_item_user_criteria_mtom

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Thanks 
Eshwar