Guard clause instead of wrapping the code inside a conditional expression Rails

Question

There is the following code:

# API controller for authentication class Api::V1::SessionsController < Api::V1::ApplicationController   skip_before_action :authorize    def create     @user = User.find_by(email: params[:user][:email])     unless @user && @user.authenticate(params[:user][:password])       @error_message = 'Invalid username or password'       render 'shared/error', status: :unauthorized     end   end end 

I use Rubocop to check my code if it matches to Ruby guidelines. I got the following error:

Use a guard clause instead of wrapping the code inside a conditional expression.     unless @user && @user.authenticate(params[:user][:password]) 

So, I don't understand how I can make this code better using guard clause. Thanks in advance!

Answer 1

Following rubocops spec : https://www.rubydoc.info/gems/rubocop/RuboCop/Cop/Style/GuardClause

Something like...

return if @user && @user.authenticate(params[:user][:password]) @error_message = 'Invalid username or password' render 'shared/error', status: :unauthorized 

Answer 2

There is a handy rule in programming, the name is "eager return" so in this case what this Guard clause instead of wrapping the code inside a conditional expression alert means is that One should be probably using an eager return statement instead of wrapping code inside an if statement (block of code inside an if or any other conditional)

So it is better to declare this:

  def method_name     return unless something?     # some code logic here   end 

Than this...

def method_name   if something?     # some code logic here   end end 

In coding we are always looking for simplicity and atomic definitions and eager return statements are a really nice way to tight up the code.