Based on the documentations. Exists can have 4 parameters:
exists:table,id,where,0
The question is, What if I wanted it to be where is not. Lik
I know you're looking for 'not 0', but for reference sake, you can use NOT_NULL, as in:
NOT_NULL
'groups' => 'required|exists:groups,jid,parent,NOT_NULL'
It's not listed in the docs right now, but here is the discussion about it (see very last post)