gistfile1.rb

# new model:
# /app/models/letsgo_user.rb
belongs_to :user
belongs_to :letsgo

# changes these models:

# /app/models/user.rb
has_many :letsgo_users
has_many :letsgos, through: :letsgo_users

# /app/models/letsgo.rb
has_many :letsgo_users
has_many :users, through: :letsgo_users

def link_to_user(user_object)
  letsgo_users.where(user_id: user_object.id).first_or_create
end


# /app/controllers/letsgo_controller.rb
#create action
@letsgo.save
@letsgo.link_to_user(current_user)

#repost action
@letsgo = Letsgo.find(params[:id])
@letsgo.link_to_user(current_user)