We are working on a custom theme for our Omeka archive. In the theme is a customized version of the items/advanced-search page. We edited the advanced-search page to allow multiple ('multiple' => 'true',) for the collections list. However, when we actually select multiple collections and then try to search (search button), we received the following error:
Mysqli prepare error: Operand should contain 1 column(s)
Would anyone happen to have any suggestions as to how to go about troubleshooting and / or fixing search functionality to allow for multiple collection IDs?