How to filter out certain objects in a table with certain ids? (Rails 4, Postgresql) -

before ask question, provide context.

i have 3 models interact each other.

scoreboard has many teams. team belongs scoreboard. 

the following use through table.

scoreboard many-to-many user.(let's call scoreboard.followers)  team many-to-many user.(let's call team.members) 

i have team_members controllers following method:

team_member#new method:

def new          @selected = true         @scoreboard = scoreboard.find(params[:scoreboard_id])         @team = team.find(params[:team_id])         @team_members = @team.members         @followers = @scoreboard.followers.search(params[:search]).paginate(page: params[:page], per_page: 50) end 

what i'm attempting display scoreboard followers in new.html.erb view. can search through them , add members team associated same scoreboard.

here's new.html.erb view:

<%= form_tag(new_scoreboard_team_team_member_path, :method => "get", id: "member-search-form", autocomplete: "off") %> <div class="row new-member-field">     <div class="col-xs-12 col-sm-6">         <%= text_field_tag :search, params[:search], placeholder: "filter members name", class:"form-control" %>     </div> </div> <% end %>  <% if @followers.any? %>            <% @followers.each |follower| %>             <div class="row member-follower-div" id="follower_<%=follower.id%>">                 <div class="col-xs-10 col-sm-5 member-prof-link">                     <%= link_to follower.name, user_path(follower.id) %>                 </div>                 <div class="col-xs-2 col-sm-1 member-add">                     <%= link_to (add_scoreboard_team_team_member_path(@scoreboard,@team, follower)), method: :post, remote: true, :data => {:disable_with => ".."} %>                         <i class="fa fa-plus-square fa-lg" aria-hidden="true"></i>                     <% end %>                 </div>             </div>         <% end %>           <div class="row">             <div class="col-xs-12 col-sm-6 new-member-pages">                 <%= will_paginate @followers %>             </div>         </div>  <% end %> 

okay question. problem arises in controller method. @team.members , @scoreboard.followers both source objects users table. how filter out user objects @scoreboard.followers exist in @team.members? don't want display @followers on view part of @team.members collection. also, bonus, alphabetically order followers user.name.

i tried .where("users.id not in (?)", @team_members.pluck(:id)) if @team_members collection null, no results displayed on page.

i solved so:

def new          @selected = true         @scoreboard = scoreboard.find(params[:scoreboard_id])         @team = team.find(params[:team_id])         @team_members = @team.members         if (@team_members.any?)            @wonderful_humans = @scoreboard.favourited_by.where("users.id not in (?)", @team_members.pluck(:id)).search(params[:search]).sort_by{ |a| a.name.downcase }         else            @wonderful_humans = @scoreboard.favourited_by.search(params[:search]).sort_by{ |a| a.name.downcase }         end         @followers = @wonderful_humans.paginate(page: params[:page], per_page: 50)     end