Best way to refactor a Rails app using Rubocop

Question

I am working on a scholarship application, where people can make donations to support persons for different programs that they want to participate in. I need some help with Rubocop refactoring in rails.

I have the following issues;

1. Controller action only calls one model method other than an initial find or new. Make custom .new or .update methods in the model with all necessary.
2. Assignment Branch Condition size for index is too high
3. Method has too many lines

I have tried to refactor the code, but I am still facing the same issues with the code.

My codes are;

Dashboard Controller (Initial*)

class DashboardController < ApplicationController
  def index
    #Paid Donations in Chart
    @paid_donations = Donation.where(payment: true).count
    #Unpaid Donations in Chart
    @unpaid_donations = Donation.where(payment: false).count
    #Total Donations Sum
    @total_donations_sum = Donation.where(payment: true).sum(:amount)
    #Deployed Donations
    @deployed_donations = Donation.where(deployment: true).sum(:amount)
    #Not Deployed Donations
    @not_deployed_donations = Donation.where(deployment: false,  payment: true).sum(:amount)
    #Deployed Donations Percentage
    @deployed_donations_percentage = (@deployed_donations.to_f / @total_donations_sum.to_f) * 100
    #Not Deployed Donations Percentage
    @not_deployed_donations_percentage = (@not_deployed_donations.to_f / @total_donations_sum.to_f) * 100

    #Total Donations
    @total_donations = Donation.count
    #Paid Donations
    @paid_donations = Donation.where(payment: true).count
    #Unpaid Donations
    @unpaid_donations = Donation.where(payment: false).count

    #All Programs
    @programs = Program.all
  end
end

Dashboard Controller (Refactored)

class DashboardController < ApplicationController    
  def index
    # Paid Donations in Chart
    @paid_donations = Donation.paid_count
    # Unpaid Donations in Chart
    @unpaid_donations = Donation.unpaid_count
    # Total Donations Sum
    @total_donations_sum = Donation.paid_sum
    # Deployed Donations
    @deployed_donations = Donation.deployed_sum
    # Not Deployed Donations
    @not_deployed_donations = Donation.not_deployed_sum
    # Deployed Donations Percentage
    @deployed_donations_percentage = percentage(@deployed_donations, @total_donations_sum)
    # Not Deployed Donations Percentage
    @not_deployed_donations_percentage = (@not_deployed_donations.to_f / @total_donations_sum.to_f) * 100

    # Total Donations
    @total_donations = Donation.count
    # Paid Donations
    @paid_donations = Donation.paid_count
    # Unpaid Donations
    @unpaid_donations = Donation.unpaid_count

    # All Programs
    @programs = Program.all
  end
end

Donation Model (Initial)

class Donation < ApplicationRecord
  belongs_to :program
end

Donations Model (Refactored)

Class Donation < ApplicationRecord
  belongs_to :program
  scope :paid_count, -> { where(payment: true).count }
  scope :unpaid_count, -> { where(payment: false).count }
  scope :paid_sum, -> { where(payment: true).sum(:amount) }
  scope :paid_sum, -> { where(payment: true).sum(:amount) }
  scope :deployed_sum, -> { where(deployment: true).sum(:amount) }
  scope :not_deployed_sum, -> { where(deployment: false).sum(:amount) }

  def percentage(donate, total)
    (donate.to_f / total.to_f) * 100
  end
end

I need some assistance on the rails best practices to resolve these issues, following the skinny models and skinny controllers rails principle.

Answer 1

I think in this case you can create method in model Donation to return all value to show in 1 hash.

Class Donation < ApplicationRecord
  belongs_to :program
  scope :paid_count, -> { where(payment: true).count }
  scope :unpaid_count, -> { where(payment: false).count }
  scope :paid_sum, -> { where(payment: true).sum(:amount) }
  scope :deployed_sum, -> { where(deployment: true).sum(:amount) }
  scope :not_deployed_sum, -> { where(deployment: false).sum(:amount) }

  def self.deployed_donations_percentage
    (deployed_sum / size) * 100
  end

  def self.not_deployed_donations_percentage
    (not_deployed_sum / size) * 100
  end

  def self.info
    {}.tap do |info|
      info[:paid_donations] = paid_count
      info[:unpaid_donations] = unpaid_count
      info[:total_donations_sum] = paid_count
      info[:deployed_donations_percentage] = deployed_donations_percentage
      info[:not_deployed_donations_percentage] = not_deployed_donations_percentage
      #...anything you want to show
    end

  end
end

in your controller

class DashboardController < ApplicationController    
  def index
    # donations info
    @donations_info = Donation.info
    # All Programs
    @programs = Program.all
  end
end

and in your view you can access value with

<%= @donations_info[:paid_donations] %>