undefined method `money' for #<ActiveRecord::Relation [#<Account id: nil, money: 400.0>]>

Question

NoMethodError in AccountsController#update
undefined method `money' for #<ActiveRecord::Relation [#<Account id: nil, money: 400.0>]>

I'm tring to get a value from database and compare to another.
After compere I want to sum then update.
Ex: Value from money database is 4000
money_to_take is 1000
if money is >= money_to_take then money = money - money_to_take update the money value with 3000.

I do not know correctly where do I have to put this code.

Can some one help me how to solve this problem? Help me please!

model/account.rb

class Account < ApplicationRecord
  belongs_to :user
  enum status: {blocked: "blocked", activated: "activated"}

  validates :number, presence: true, uniqueness: true 
  validates :money, presence: true, length: {minimum:1}

   def self.update_withdraw_money(account_number, money_to_take) 
      account = select(:money).where(number:account_number)
      if account.money >= money_to_take
      @account.money -= money_to_take 
      end
   end

end

This is the error line

if account.money >= money_to_take

Controllers/accounts_controller.rb

  def withdraw
    @account = Account.where(params[:number]).first
    account = @account
    account.money = 0.0;
    @account_withdraw = account

    logger.debug {"Last acount attributes hash: #{@account_withdraw.attributes.inspect}"}
  end


  def update

    Account.update_withdraw_money(@account.number, @account.money)

    respond_to do |format|
      if @account.update(account_params)
        format.html { redirect_to account_url(@account), notice: "Account was successfully updated." }
        format.json { render :show, status: :ok, location: @account }
      else
        format.html { render :edit, status: :unprocessable_entity }
        format.json { render json: @account.errors, status: :unprocessable_entity }
      end
   end
  end

    def account_params
      params.require(:account).permit(:money, :status)
    end

account table

class CreateAccounts < ActiveRecord::Migration[7.0]
  def change
    create_table :accounts do |t|
      t.integer :number, default: 10000
      t.float :money, default: 0.5
      t.string :status, default: "activated"
      t.references :user, null: false, foreign_key: true

      t.timestamps
    end
  end
end

accounts/withdraw.html.erb

<h1>Withdraw from my account</h1>

<%= render "accounts/form", account: @account_withdraw%>

accounts/_form

<%= form_with(model: account) do |form| %>
  <% if account.errors.any? %>
    <div style="color: red">
      <h2><%= pluralize(account.errors.count, "error") %> prohibited this account from being saved:</h2>

      <ul>
        <% account.errors.each do |error| %>
          <li><%= error.full_message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div>
    <%= form.label :money, style: "display: block" %>
    <%= form.text_field :money %>
  </div>

  <div>
    <%= form.hidden_field :status, value: "activated" %>
  </div>

  <div>
    <%= form.submit %>
  </div>
<% end %>

Use this address to access application http://127.0.0.1:3000/accounts/1000/withdraw .
Here is my code in github https://github.com/Vicente-jpro/negocial-app

Answer 1

Something like this

def self.update_withdraw_money(account_number, money_to_take) 
  account = find_by(number: account_number)

  if account.money >= money_to_take
    account.decrement!(:money, money_to_take)
  end
end

After that you need @account.reload in the controller, because record is updated

And may be you need to wrap these updates into transaction