I am building and Rails 5 API where I am trying to send money amount and store it in PostgresQL database. I am sending amount 2.4 but I see in database only 2 is stored. what I am doing wrong?
my migration:
class CreateTransactions < ActiveRecord::Migration[5.1]
def change
create_table :transactions do |t|
t.monetize :transaction_price, amount: { null: true, default: nil }
t.timestamps
end
end
end
my model is:
class Transaction < ApplicationRecord
monetize :transaction_price_cents
end
my controller:
class TransactionsController < ApiController
def create
transaction = Transaction.new(transaction_param)
if transaction.save
render json: { status: 'SUCCESS', data:transaction }, status: :ok
end
end
private
def transaction_param
params.require(:transaction).permit(:transaction_price_cents)
end
end
I am sending this json with postman:
{
"transaction_price_cents": 345.23
}
What I am getting in response:
{
"status": "SUCCESS",
"data": {
"id": 1,
"transaction_price_cents": 345,
"transaction_price_currency": "USD",
}
}
I either want 345.23 or 34523 but its giving me only 345!
Your price in cents! And that's ok!
Handling money in cents is a common pattern. It will also save your life when it comes to rounding errors with taxes or currency exchange. Like in their docs mentioned you should use a helper to output the price in a human readable form:
humanized_money #money_object # => 6.50
humanized_money_with_symbol #money_object # => $6.50
money_without_cents_and_with_symbol #money_object # => $6
If you accessing the data via an API you could add a human_readable field in your api
def transaction_price_human_readable
return humanized_money_with_symbol(#money_object) # or self or...
end
Save/Create model: If you get a floating number you could change the floating point into cents before_save
before_save :convert_transaction_price
def convert_transaction_price
self.transaction_price = (self.transaction_price * 100).to_i
end
I had the same problem.
(EDITED NEW AND CORRECT ANSWER):
All I had to do was to use the provided attribute from the money-rails gem. In my case I had an amount_cents attribute, and I had to use the provided :amount attribute in the form.
<%= f.label :amount %>
<%= f.text_field :amount %>
NOTE: I converted the value of :amount_cents to a float string in the edit.html.erb as followed:
<%= f.label :amount %>
<%= f.text_field :amount, value: number_with_precision(f.object.amount_cents / 100, precision: 2).gsub(/\./, ',') %>
(also note that I had configured money-rails to use EUROs which use "," as delimiter, thats why i have to use .gsbu(/\./, ','))
And here ist the IMPORTANT PART, I had to update my strong_parameters in the controller to permit :amount, and not :amount_cents
private
def invoice_params
params.require(:invoice).permit(…, :amount, …)
end
--
(OLD ANSWER):
I came to the conclusion that it is best to change the input value directly in the Frontend to cents. And then send the cents to the backend.
Here is a nice Stimulus Controller which does exactly that: https://gist.github.com/psergi/72f99b792a967525ffe2e319cf746101
(You may need to update that gist to your liking, and also it expects that you use Stimulus in your rails project)
(I leave the old answer in here, because I think it is a good practice to send _cents from the frontend to the backend, but in the moment it is not necessary [for me]. If you want to support more than one currency, you probably want to do it like that and use a .js framework to handle the input conversion -> s.th. like http://autonumeric.org/)
I'm fairly new to rails and having a problem that I'm sure is not unique, but can't seem to find an elegant solution to on my own:
I have a model with a :tax_rate decimal attribute that is used to create a total later on using some multiplication in the model.
This works just fine if the user enters the tax rate as '0.09' in the tax rate field, but obviously creates an erroniously large amount when the user enters '9'.
I'm looking to create some code that will handle a whole number being entered into my form.
My form:
<td><%= f.input :tax_rate, label: false, input_html: { class: 'taxtarget', precision: 2 }%></td>
The calcualtions in the model:
before_save :persist_calculations
validates_presence_of :price, :units
def calculated_total
price * units + calculated_tax
end
def calculated_tax
if self.tax_rate.present?
self.price * self.tax_rate
else
self.price
end
end
def persist_calculations
self.total = calculated_total
self.tax_amount = calculated_tax
end
I would like to either handle the whole number by preventing a whole number (requiring a decimal point) or by converting a whole number into a decimal by adding two decimal places to it.
Anyone have any good resources or ideas for how to accomplish this?
Either add a validation to your model for tax_rate so that it cannot be a larger than 1.0:
validates :tax_rate, less_than: 1.0
and/or add a before_validation to your model that converts large numbers to small ones:
before_validation ->(obj) {
obj.tax_rate = obj.tax_rate / 100 if obj.tax_rate > 1
}
and/or handle it your controller, which is generally preferable to using callbacks.
I am using Rails 3.2.17 and am storing prices for items like this (an example migration):
add_column :item_counts, :per_item_cost, :decimal, :precision => 8, :scale => 2
but if it's 23.00, it comes out as 23.0. I tend to create a method like this:
def helpers
ActionController::Base.helpers
end
def per_item_cost_formatted
helpers.number_to_currency(per_item_cost, precision: 2, format: "%n")
end
Is there a way I can specify that it always outputs formatted to be 23.00? Something like:
def per_item_cost
helpers.number_to_currency(per_item_cost, precision: 2, format: "%n")
end
causes an endless loop.
Use number_with_precision:
include ActionView::Helpers::NumberHelper
def per_item_cost
number_with_precision(read_attribute(:per_item_cost), precision: 2)
end
I have a model like this.
class Money
include Mongoid::Document
#interval is how often the compensation is paid
field :salary, :type => Integer # must be saved in cents
field :commission, :type => Integer # must be saved in cents
field :total, :type => Integer # must be saved in cents
end
total is sum of salary and commission. salary and commission both are saved in cents.
But my problem is that when it is edited i need to show it in dollar figure.
For example, if salary in cent is 5000000 then when i press edit i need to see 50000 in the salary textbox.
Some other solutions are also welcomed
If you want to enforce this pattern at the model level then you could override the setters and getters:
class Money
#...
def salary
self.salary / 100
end
def salary=(value)
self.salary * 100
end
end
In this case you'll have the editing/displaying for free, without writing any helpers.
Although, I think the proper way for doing it is at the view level through a helper definition. The model should not be concerned with this.
Look at ActionView::Helpers::NumberHelper. In your case you could write your own helper like this:
def money_to_textbox (money)
money / 100
end
This helper method should be placed in app\helpers and then in a view you can use like this:
<%= money_to_textbox #money %>
I'm working on a very basic shopping cart system.
I have a table items that has a column price of type integer.
I'm having trouble displaying the price value in my views for prices that include both Euros and cents. Am I missing something obvious as far as handling currency in the Rails framework is concerned?
You'll probably want to use a DECIMAL type in your database. In your migration, do something like this:
# precision is the total number of digits
# scale is the number of digits to the right of the decimal point
add_column :items, :price, :decimal, :precision => 8, :scale => 2
In Rails, the :decimal type is returned as BigDecimal, which is great for price calculation.
If you insist on using integers, you will have to manually convert to and from BigDecimals everywhere, which will probably just become a pain.
As pointed out by mcl, to print the price, use:
number_to_currency(price, :unit => "€")
#=> €1,234.01
Here's a fine, simple approach that leverages composed_of (part of ActiveRecord, using the ValueObject pattern) and the Money gem
You'll need
The Money gem (version 4.1.0)
A model, for example Product
An integer column in your model (and database), for example :price
Write this in your product.rb file:
class Product > ActiveRecord::Base
composed_of :price,
:class_name => 'Money',
:mapping => %w(price cents),
:converter => Proc.new { |value| Money.new(value) }
# ...
What you'll get:
Without any extra changes, all of your forms will show dollars and cents, but the internal representation is still just cents. The forms will accept values like "$12,034.95" and convert it for you. There's no need to add extra handlers or attributes to your model, or helpers in your view.
product.price = "$12.00" automatically converts to the Money class
product.price.to_s displays a decimal formatted number ("1234.00")
product.price.format displays a properly formatted string for the currency
If you need to send cents (to a payment gateway that wants pennies), product.price.cents.to_s
Currency conversion for free
Common practice for handling currency is to use decimal type.
Here is a simple example from "Agile Web Development with Rails"
add_column :products, :price, :decimal, :precision => 8, :scale => 2
This will allow you to handle prices from -999,999.99 to 999,999.99
You may also want to include a validation in your items like
def validate
errors.add(:price, "should be at least 0.01") if price.nil? || price < 0.01
end
to sanity-check your values.
Just a little update and a cohesion of all the answers for some aspiring juniors/beginners in RoR development that will surely come here for some explanations.
Working with money
Use :decimal to store money in the DB, as #molf suggested (and what my company uses as a golden standard when working with money).
# precision is the total number of digits
# scale is the number of digits to the right of the decimal point
add_column :items, :price, :decimal, precision: 8, scale: 2
Few points:
:decimal is going to be used as BigDecimal which solves a lot of issues.
precision and scale should be adjusted, depending on what you are representing
If you work with receiving and sending payments, precision: 8 and scale: 2 gives you 999,999.99 as the highest amount, which is fine in 90% of cases.
If you need to represent the value of a property or a rare car, you should use a higher precision.
If you work with coordinates (longitude and latitude), you will surely need a higher scale.
How to generate a migration
To generate the migration with the above content, run in terminal:
bin/rails g migration AddPriceToItems price:decimal{8-2}
or
bin/rails g migration AddPriceToItems 'price:decimal{5,2}'
as explained in this blog post.
Currency formatting
KISS the extra libraries goodbye and use built-in helpers. Use number_to_currency as #molf and #facundofarias suggested.
To play with number_to_currency helper in Rails console, send a call to the ActiveSupport's NumberHelper class in order to access the helper.
For example:
ActiveSupport::NumberHelper.number_to_currency(2_500_000.61, unit: '€', precision: 2, separator: ',', delimiter: '', format: "%n%u")
gives the following output
2500000,61€
Check the other options of number_to_currency helper.
Where to put it
You can put it in an application helper and use it inside views for any amount.
module ApplicationHelper
def format_currency(amount)
number_to_currency(amount, unit: '€', precision: 2, separator: ',', delimiter: '', format: "%n%u")
end
end
Or you can put it in the Item model as an instance method, and call it where you need to format the price (in views or helpers).
class Item < ActiveRecord::Base
def format_price
number_to_currency(price, unit: '€', precision: 2, separator: ',', delimiter: '', format: "%n%u")
end
end
And, an example how I use the number_to_currency inside a contrroler (notice the negative_format option, used to represent refunds)
def refund_information
amount_formatted =
ActionController::Base.helpers.number_to_currency(#refund.amount, negative_format: '(%u%n)')
{
# ...
amount_formatted: amount_formatted,
# ...
}
end
If you are using Postgres (and since we're in 2017 now) you might want to give their :money column type a try.
add_column :products, :price, :money, default: 0
Use money-rails gem. It nicely handles money and currencies in your model and also has a bunch of helpers to format your prices.
Using Virtual Attributes (Link to revised(paid) Railscast) you can store your price_in_cents in an integer column and add a virtual attribute price_in_dollars in your product model as a getter and setter.
# Add a price_in_cents integer column
$ rails g migration add_price_in_cents_to_products price_in_cents:integer
# Use virtual attributes in your Product model
# app/models/product.rb
def price_in_dollars
price_in_cents.to_d/100 if price_in_cents
end
def price_in_dollars=(dollars)
self.price_in_cents = dollars.to_d*100 if dollars.present?
end
Source: RailsCasts #016: Virtual Attributes: Virtual attributes are a clean way to add form fields that do not map directly to the database. Here I show how to handle validations, associations, and more.
Definitely integers.
And even though BigDecimal technically exists 1.5 will still give you a pure Float in Ruby.
If someone is using Sequel the migration would look something like:
add_column :products, :price, "decimal(8,2)"
somehow Sequel ignores :precision and :scale
(Sequel Version: sequel (3.39.0, 3.38.0))
My underlying APIs were all using cents to represent money, and I didn't want to change that. Nor was I working with large amounts of money. So I just put this in a helper method:
sprintf("%03d", amount).insert(-3, ".")
That converts the integer to a string with at least three digits (adding leading zeroes if necessary), then inserts a decimal point before the last two digits, never using a Float. From there you can add whatever currency symbols are appropriate for your use case.
It's definitely quick and dirty, but sometimes that's just fine!
I am using it on this way:
number_to_currency(amount, unit: '€', precision: 2, format: "%u %n")
Of course that the currency symbol, precision, format and so on depends on each currency.
You can pass some options to number_to_currency (a standard Rails 4 view helper):
number_to_currency(12.0, :precision => 2)
# => "$12.00"
As posted by Dylan Markow
Simple code for Ruby & Rails
<%= number_to_currency(1234567890.50) %>
OUT PUT => $1,234,567,890.50