如何在Rails中获得where id => id集合的逆函数

Question

I'm trying to return the inverse of this statement:

scope :subscribed, lambda {|user| where(:venue_id => user.flagged_venues)}

flagged_venues returns an array of ids, so when I run that statement I get all of the flagged venues. What I actually want is the exact opposite: all the venues except for the flagged ones.

I tried it with != instead of => but that returned all the venues.

When it's changed to where("venue_id <> ?", user.flagged_venues) then I get this error: PG::DatatypeMismatch: ERROR: argument of WHERE must be type boolean, not type record LINE 1: SELECT "events".* FROM "events" WHERE (venue_id <> 2,4)

Answer 1

You want the ids that are not in the list of flagged_venues , so my guess is that you should replace

where(:venue_id => user.flagged_venues)

by

where("venue_id not in (?)", user.flagged_venues)