Rails ActiveRecord: Find All Users Except Current User

ghz 1years ago ⋅ 7688 views

Question

I feel this should be very simple but my brain is short-circuiting on it. If I have an object representing the current user, and want to query for all users except the current user, how can I do this, taking into account that the current user can sometimes be nil?

This is what I am doing right now:

def index
  @users = User.all
  @users.delete current_user
end

What I don't like is that I am doing post-processing on the query result. Besides feeling a little wrong, I don't think this will work nicely if I convert the query over to be run with will_paginate. Any suggestions for how to do this with a query? Thanks.

Answer

It is possible to do the following in Rails 4 and up:

User.where.not(id: id)

You can wrap it in a nice scope.

scope :all_except, ->(user) { where.not(id: user) }
@users = User.all_except(current_user)

Or use a class method if you prefer:

def self.all_except(user)
  where.not(id: user)
end

Both methods will return an AR relation object. This means you can chain method calls:

@users = User.all_except(current_user).paginate

You can exclude any number of users because [where()](http://edgeguides.rubyonrails.org/active_record_querying.html#not- conditions) also accepts an array.

@users = User.all_except([1,2,3])

For example:

@users = User.all_except(User.unverified)

And even through other associations:

class Post < ActiveRecord::Base
  has_many :comments
  has_many :commenters, -> { uniq }, through: :comments
end

@commenters = @post.commenters.all_except(@post.author)

See where.not() in the [API Docs](http://edgeguides.rubyonrails.org/active_record_querying.html#not- conditions).

#ruby