Calculate Monthly Totals

Question

Hello I am creating a little app to help me manage my credit cards.

I have a User Model and a Credit Card Model

class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  has_many :credit_cards
end

class CreditCard < ApplicationRecord
  belongs_to :user
  def credit_available
    limit - balance
  end

  def annual_interest
    if self.balance && self.interestRate
      self.balance * self.interestRate
    else
      "0.0".to_d
    end
  end


  def minimum_payment
    n = balance / 100
    b = n * 1
    i = balance * interestRate
    c = i / 12

    c + b
  end

end

As you can see I have calculated a methods including monthly_payment in my credit_cards model

Now I want to total my credit card payments on a monthly basis. so I added another method to my credit cards model called total_monthly_payment which totals the current_users credit_card monthly_payments into a sum.

def total_monthly_payment

    n = current_user.credit_cards.sum(minimum_payment)

    n
  end

the view sits like so

<% if user_signed_in? %>
  Credit Cards

  <% if current_user.credit_cards.any? %>
    
        <% @credit_cards.each do |credit_card| %>
          
        <% end %>
      
      
        
          <%= link_to 'Name', :sort => 'card_NickName'  %>  
          <%= link_to 'Provider', :sort => 'card_provider' %>
          <%= link_to 'Points', :sort => 'points_provider'   %>
          %
          Balance
          Limit
          Available
          Min Payments
          
        
      

      
            <%= link_to credit_card.nickName, credit_card %>
            <%= credit_card.provider %>
            <%= credit_card.pointsProvidor %>
            <%= number_to_percentage(credit_card.interestRate * 100, precision: 2) %>
            <%= number_to_currency(credit_card.balance, unit: "$") %>
            <%= number_to_currency(credit_card.limit, unit: "$") %>
            <%= number_to_currency(credit_card.credit_available, unit: "$") %>
            <%= number_to_currency(credit_card.minimum_payment, unit: "$") %>
            
            
            
          
      
        
          
          
          
          
          <%= number_to_currency(@credit_card_debt, unit: "$") %>
          <%= number_to_currency(@credit_limit, unit: "$") %>
          <%= number_to_currency(@available_credit, unit: "$") %>
          <%= @total_monthly_payment %>
          
          
          
        
      
    

    


    <%= link_to new_credit_card_path, class: 'mdl-button mdl-js-button mdl-button--fab mdl-button--colored' do %>
            add
        <% end %>
  <% else %>
    You have no Credit Cards, better
    <%= link_to new_credit_card_path, class: 'mdl-button mdl-js-button mdl-button--fab mdl-button--colored' do %>
      add
    <% end %>
    one.
  <% end %>
<% else %>

  
  Credit Card Smarts at your fingertips
  
<% end %>

all works well untill i try to calculate the @total_monthly_payment when i get the following error.

NameError in CreditCardsController#index
undefined local variable or method `balance' for #
Extracted source (around line #5):
3
4
5
6
7
8


  def minimum_payment
    n = balance / 100
    b = n * 1
    i = balance * interestRate
    c = i / 12

controller

class CreditCardsController < ApplicationController
  before_action :authenticate_user!
  before_action :set_credit_card, only: [:show, :edit, :update, :destroy]

  # GET /credit_cards
  # GET /credit_cards.json
  def index
    @credit_cards = current_user.credit_cards
    @credit_card_debt = current_user.credit_cards.sum(:balance)
    @credit_limit = current_user.credit_cards.sum(:limit)
    @available_credit = current_user.credit_cards.sum(:limit) - current_user.credit_cards.sum(:balance)
    @total_monthly_payment = total_monthly_payment
  end



  # GET /credit_cards/1
  # GET /credit_cards/1.json
  def show
  end

  # GET /credit_cards/new
  def new
    @credit_card = current_user.credit_cards.build
  end

  # GET /credit_cards/1/edit
  def edit
  end

  # POST /credit_cards
  # POST /credit_cards.json
  def create
    @credit_card = current_user.credit_cards.new(credit_card_params)

    respond_to do |format|
      if @credit_card.save
        format.html { redirect_to @credit_card, notice: 'Credit card was successfully created.' }
        format.json { render :show, status: :created, location: @credit_card }
      else
        format.html { render :new }
        format.json { render json: @credit_card.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /credit_cards/1
  # PATCH/PUT /credit_cards/1.json
  def update
    respond_to do |format|
      if @credit_card.update(credit_card_params)
        format.html { redirect_to @credit_card, notice: 'Credit card was successfully updated.' }
        format.json { render :show, status: :ok, location: @credit_card }
      else
        format.html { render :edit }
        format.json { render json: @credit_card.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /credit_cards/1
  # DELETE /credit_cards/1.json
  def destroy
    @credit_card.destroy
    respond_to do |format|
      format.html { redirect_to credit_cards_url, notice: 'Credit card was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
  # Use callbacks to share common setup or constraints between actions.
  def set_credit_card
    @credit_card = CreditCard.find(params[:id])
  end

  # Never trust parameters from the scary internet, only allow the white list through.
  def credit_card_params
    params.require(:credit_card).permit(:nickName, :provider, :pointsProvidor, :interestRate, :balance, :limit, :user_id )
  end
end

Please help!

barmic · Accepted Answer

Modify your model method in this way:

def total_monthly_payment
    n = current_user.credit_cards.sum(&:minimum_payment)
end

Calculate Monthly Totals

Answers (2)

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