How can I manipulate a decimal or integer column in a callback before saving to database

I am having a model Factsheet which has some decimal columns, for entering some $ values(price). I need to be able to enter values like $1,000,000.00 and calculate the original value from them before saving. If I do the save, before any formatting, it will save it as 1.00 as "$1,000,000.00".to_f = 1.0 I was trying to do a before_save callback, and extract the digits and dots only from the column before saving it. Here is how I went about it:

class Factsheet < ActiveRecord::Base
  before_save :convert_to_decimal

  def convert_to_decimal
    self.shopping_center_size = decimal_value(shopping_center_size)
    self.cam = decimal_value(cam)
    self.tax = decimal_value(tax)
    #... some other manipulations
  end

  def decimal_value(string)
    string ? string.gsub(/[^\d\.]/, "") : string
  end
end

But, this code is not working as Rails convert the parameters into BigDecimal (I believe it performs to_f to the string). So I am getting NoMethod gsub for BigDecimal when I execute this code. I know I can manipulate the params in the controller itself before saving, or pass the params to a class method in the model and开发者_JS百科 manipulate it there. But, both these options doesnt seem right. Is there anyway, I can manipulate them in the callback itself?

Controller:

def FactsheetsController < ApplicationController
  def new
    @factsheet = Factsheet.new
  end

  def create
    @factsheet = Factsheet.new(params[:factsheet])
    if @factsheet.save
      flash[:notice] = "Factsheet created successfully"
      redirect_to @factsheet
    else
      render :action => "new"
    end
  end

  def edit
    @factsheet = Factsheet.find(params[:id])
  end

  def update
    @factsheet = Factsheet.find(params[:id])
    if @factsheet.update_attributes(params[:factsheet])
      flash[:notice] = "Factsheet updated successfully"
      redirect_to @factsheet
    else
      render :action => "edit"
    end
  end
end

View:

_form.html.erb

# Here user should be able to enter values like $1,000,000.00
# and it should be correctly saved to database as 1000000.0
<%= form.text_field :cam %>
<%= form.text_field :tax %>

You can override the set method of each field in the model, like this:

def shopping_center_size=(num)
   self[:shopping_center_size] = decimal_value(num)
end

def cam=(num)
   self[:cam] = decimal_value(num)
end

def tax=(num)
   self[:tax] = decimal_value(num)
end