Wsrtjtyk

This should be easy I think...

A Organisation has an Owner and Members - both are Users.

This is setup by the organisation using class_name: "User", like so:

class Organisation < ApplicationRecord

   belongs_to :owner, class_name: "User", foreign_key: "owner_id"

   has_many :organisations_users

   has_many :members, class_name: "User", through: :organisations_users, source: :user

end

This works but I need an all_members function (or scope) so I can get back both owner and members in one array (or ActiveRecord object). I thought this would be trivial but it's actually not.

I've tried:

def all_members

   members << owner

end

this of course is not what I want at all... this adds the owner to the staff every time I call it.

def all_members

   [owner, members]

end

this sort of works but returns a nested array which is hard to access properly.

  scope :all_members, joins(:members).merge(:owner)

this doesn't work at all. Probably nonsense.

  def all_members

     members_array = members.dup

     members_array << owner

  end

This still permanently alters the members to include the owner?!!

Help! (Thanks)

If the order is not necessarily important then we can get this into a single query like so:

If Rails 5

def all_members

  # not sure if you could just do 

  # owner.or(members) since they are both User 

  # but it seems unlikely due to the join table 

  User.where(id: self.owner_id).or(

    User.where(id: organisation_users.select(:user_id))

  )

end 

All versions of Rails (less than and including Rails 5) we can use Arel to build the more complex query

def all_members

  user_table = User.arel_table   

  User.where(

    users_table[:id].eq(self.owner_id).or(

       users_table[:id].in(

         organisation_users.select(:user_id).arel

       )

    )

  ) 

end 

these will both result in the following SQL

SELECT users.* 

FROM users 

WHERE 

  (users.id = [YOUR_OWNER_ID] OR 

   users.id IN (

     SELECT organisations_users.user_id 

     FROM organisations_users

     WHERE organisations_users.organisation_id = [YOUR_ORGANISATION_ID]

  ))

the end result will be an ActiveRecord::Relation of User objects.

If getting an Array back is sufficient, then you can simply use:

def all_members

  [owner] + members

end

If you need a relation, then the simplest (but not most efficient) approach would be:

def all_members

  User.where(id: [owner] + members.ids)

end

It's not the most efficient as the SQL that gets generated may include a fairly large IN statement that cannot be efficiently cached by the database parser. Still, if the numbers are in the range of a few dozens, it would be enough even that relation trick.