How to convert dollars into cents for money gem

Question

There're many currencies type in my database.

suppose I have these 3 items in my database

amount: 100, currency: NTD
amount:100, currency: USD
amount:100, currency: JPY

Then

Money.new(100, :NTD), the result will be 1 dollar for NTD, but actually it should be 100 dollars.

As as in USD

However,

Money.new(100, :JPY), the result is just 100 dollars for JPY, it's as my expect.

How could I handle this situation in my case. it's not possible to acquire my user to type 100 for 1 dollar with NTD currency.

In the amount field, I want to only save the number for dollar unit.

However the money gem seems only accepts cents as its input.

Is there any good practice to solve my problem.

Are you able to multiply the amount the user-provided amount by 100? — Daniel M., Sep 20 '15 at 02:26
so I have to write `if else` condition, if user choose USD or TWD i should multiply 100, if `JPY` i don't have to multiply `100`. these will add complexity in my app. prone to make new bugs, i'm finding if there is more elegant solution T_T — newBike, Sep 20 '15 at 02:36

score 0 · Answer 1 · answered Sep 20 '15 at 04:24

This is my current solution, however i think it smells bad

I hope there is some solutions can beat my current workaround

CurrencyUtil.money_to_target_currency( price , from_currency, to_currency)

lib/currency_util.rb

module CurrencyUtil

  def self.dollar_to_cents(amount, raw_currency)
    currency = raw_currency.upcase.to_sym
    if [:TWD, :USD].include? currency
      cents = amount*100
    elsif [:JPY]
      cents = amount
    end
    return cents
  end

  def self.money_to_target_currency(amount_in_dollar, from_currency, to_currency)
    cents = dollar_to_cents(amount_in_dollar, from_currency)
    Money.new(cents, from_currency).exchange_to(to_currency)
  end

end

how's about a way to config no using cents in Money? – Hai Nguyen Apr 21 '16 at 15:47 — Hai Nguyen, Apr 21 '16 at 15:47

score 0 · Answer 2 · answered Apr 22 '16 at 11:54

If you take a look in money gem, in /config/currency_iso.json

{
  "Jpy": {
    "priority": 6,
    "iso_code": "JPY",
    "name": "Japanese Yen",
    "symbol": "¥",
    "alternate_symbols": ["円", "圓"],
    "subunit": null,
    "subunit_to_unit": 1,
    "symbol_first": true,
    "html_entity": "&#x00A5;",
    "decimal_mark": ".",
    "thousands_separator": ",",
    "iso_numeric": "392",
    "smallest_denomination": 1
  }
}

You will see that

"subunit_to_unit": 1

so in this case you should override JPY and NTD currency with

"subunit_to_unit": 100

Here is my sample code under /config/initializers/money.rb

  Money::Currency.register({
    "priority": 6,
    "iso_code": "JPY",
    "name": "Japanese Yen",
    "symbol": "¥",
    "alternate_symbols": ["円", "圓"],
    "subunit": "Sen",
    "subunit_to_unit": 100,
    "symbol_first": true,
    "html_entity": "&#x00A5;",
    "decimal_mark": ".",
    "thousands_separator": ",",
    "iso_numeric": "392",
    "smallest_denomination": 1
 })

You can add more currency in here. Hope this help you.

score 0 · Answer 3 · edited Aug 30 '17 at 21:12

0

Damn, this took me ages to figure out. Awesome gem, but had the same issue. This was my solution:

# multiply amount to convert by the subunit for currency
amount = amount * Money::Currency.new(from_symbol).subunit_to_unit
amount_exchanged = Money.new(amount, from_symbol).exchange_to(to_symbol)

edited Aug 30 '17 at 21:12

Kick Buttowski

6,709
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answered Aug 07 '17 at 12:06

Andrew Cetinic

2,805
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It removes the cent position values, 2811157 resulted in 2811100. How can I resolve this? – Anas Ansari May 05 '22 at 07:05

How to convert dollars into cents for money gem

3 Answers3

lib/currency_util.rb