A script to convert Simple.com JSON transaction export to a CSV for importing into YNAB.

banksimple_json_to_ynab_csv.rb

require 'json'
require 'csv'

class SimpleJsonExport
  def initialize(filepath)
    @filepath = filepath
  end

  def transactions
    @transactions ||= data['transactions'].collect do |transaction|
      SimpleTransaction.new(transaction)
    end
  end

  private

  attr_reader :filepath

  def file
    @file ||= File.read(filepath)
  end

  def data
    @date ||= JSON.parse(file)
  end
end

class SimpleTransaction
  def initialize(data)
    @data = data
  end

  def date
    @date ||= Date.parse(data['times']['when_recorded_local'])
  end

  def payee
    @payee ||= data['description']
  end

  def category
    @category ||= data['categories'].first['name']
  end

  def memo
    nil
  end

  def outflow
    @outflow ||= type == :debit ? amount : nil
  end

  def inflow
    @inflow ||= type == :credit ? amount : nil
  end

  private

  def amount
    @amount ||= "%.2f" % (data['amounts']['amount'] / 10000.00)
  end

  def type
    @type ||= data['bookkeeping_type'].to_sym
  end

  attr_reader :data
end

class YnabCsvExport < Struct.new(:transactions)
  def csv
    @csv ||= CSV.generate do |csv|
      csv << %w(Date Payee Category Memo Outflow Inflow)

      transactions.each do |transaction|
        date     = transaction.date.strftime('%m/%d/%Y')
        payee    = transaction.payee
        category = transaction.category
        memo     = transaction.memo
        outflow  = transaction.outflow
        inflow   = transaction.inflow

        csv << [date, payee, category, memo, outflow, inflow]
      end
    end
  end
end

filepath = 'simple_export.json'
simple_export = SimpleJsonExport.new(filepath)
transactions = simple_export.transactions
csv = YnabCsvExport.new(transactions).csv

puts csv