gistfile1.rb

post '/interests' do
  # Connect to Redis
  uri = URI.parse(ENV["REDIS_URL"] || 'redis://localhost:6379')
  REDIS = Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)

  # Parse the JSON body
  join = JSON.parse(request.body.read)

  # Register the user's interest in an artist
  REDIS.sadd("artists:#{join['artist_id']}", join['user_id'])
  REDIS.sadd("users:#{join['user_id']}", join['artist_id'])
  
  status 201
end