4 Mistakes to Avoid as a RoR Engineer

Ruby on Rails is a powerful framework that if used properly can speed up development and provide a strong foundation for a scalable application. However, some simple mistakes can quickly make Rails a burden.

Photo by Sarah Kilian on Unsplash

1. Forgetting to Check for N+1 Queries

N+1 occurs when a record collection is retrieved without loading its required associations. This leads to 1 query to fetch the original collection and N queries to fetch the association of each record. This causes a slowdown due to an unnecessarily large number of DB roundtrips. Instead, we should eager load the first query so we can make a single larger query (with the ID of all elements in association) to fetch the associated records. A great way to check for N+1 queries and get suggestions on how to fix them is the Bullet gem.

Model

class User < ApplicationRecord
  has_one :picture
end

Serializer

class UserSerializer < ApplicationSerializer
  identifier :id
  fields :name, :username, :created_at
  association :picture, blueprint: PictureSerializer
end

Controller

# WRONG
def index
  @users = User.all
  render json: UserSerializer.render(@users)
end
# CORRECT
def index
  @users = User.all.includes(:picture)…