Foo Bar

foobar_controller.rb

class FooBarController < ApplicationController
  before_action :set_stuff
  
  def create
    # same as below
    @bar.foods.add(@foo)
  end
  
  def destroy
    # remove beeing a method on the foo object here
    @bar.foos.remove(@foo)
  end
  
  private
  
  def set_stuff
    @foo = Foo.where(id: params[:foo_id])
    @bar = Bar.where(id: params[:bar_id])
  end
 end

routes.rb

...

  resources :foobar, only: [:create, :destroy]

...

views.html.erb

<%= link_to "Add", create_foobar_path(@foo, @bar) %>
<%= link_to "Remove", destroy_foobar_path(@foo, @bar), method: :destroy %>