[ruby-on-rails] Rails Model find where not equal

How can I find records in my database on a not equal condition? I have this now, but is there a fancy rails-speak way of doing it?

GroupUser.where('user_id != ?',me)

You should always include the table name in the SQL query when dealing with associations.

Indeed if another table has the user_id column and you join both tables, you will have an ambiguous column name in the SQL query (i.e. troubles).

So, in your example:

GroupUser.where("groups_users.user_id != ?", me)

Or a bit more verbose:

GroupUser.where("#{table_name}.user_id IS NOT ?", me)

Note that if you are using a hash, you don't need to worry about that because Rails takes care of it for you:

GroupUser.where(user: me)

In Rails 4, as said by @dr4k3, the query method not has been added:

GroupUser.where.not(user: me)

The only way you can get it fancier is with MetaWhere.

MetaWhere has a newer cousin which is called Squeel which allows code like this:

GroupUser.where{user_id != me}

It goes without saying, that if this is the only refactor you are going to make, it is not worth using a gem and I would just stick with what you got. Squeel is useful in situations where you have many complex queries interacting with Ruby code.

Rails 4

GroupUser.where.not(user_id: me)

In Rails 3, I don't know anything fancier. However, I'm not sure if you're aware, your not equal condition does not match for (user_id) NULL values. If you want that, you'll have to do something like this:

GroupUser.where("user_id != ? OR user_id IS NULL", me)

Rails 4:

If you want to use both not equal and equal, you can use:

user_id = 4
group_id = 27
GroupUser.where(group_id: group_id).where.not(user_id: user_id)

If you want to use a variety of operators (ie. >, <), at some point you may want to switch notations to the following:

GroupUser.where("group_id > ? AND user_id != ?", group_id, user_id)