Is there a way to do a multiselection user lookup?
Can you explain your question a bit more ; like where you are trying to do this?
Because the simple answer is just "Yes".
We have an attribute which allows you to select an specific user from a list. The thing is that it only allows you to select one user and we need to select two, that is why we need this attibute to be a multiselection one. We explore the available options, but this kind of attriubute is not like "Multi Valued Lookup - String" ones.
This attribute was created with the following Dynamic Query:
FROM srm_resources r,
WHERE u.id = r.user_id
AND r.person_type = l.id
AND u.user_status_id = s.id
AND s.language_code= @WHERE:PARAM:LANGUAGE@
AND U.ID = G.USER_ID
AND G.GROUP_ID = V.ID
AND V.LANGUAGE_CODE = 'EN'
AND s.lookup_code IN ('ACTIVE','LOCK')
So you should just be able to select the "multi-select" option* in the portlet filter-field properties against the user_id attribute?
I'm assuming here that user_id is mapped in your query to a lookup, and that user_id is the attribute you have in your portlet's filter.
* - The option to select between single-select and multi-select will only appear against a field property (in the portlet's "List Filter Section" / "Fields" ) if the query attribute is associated with a lookup and is a simple returned value rather than a user-specified parameter (which your is)