# View Source Money

Elixir library for working with Money safer, easier, and fun, is an interpretation of the Martin Fowler's Money pattern in functional programming.

"If I had a dime for every time I've seen someone use FLOAT to store currency, I'd have \\$999.997634" -- Bill Karwin

In short: You shouldn't represent monetary values by a float. Wherever you need to represent money, use `Money`.

## installation Installation

Money comes with no required dependencies.

Add the following to your `mix.exs`:

``````def deps do
[{:money, "~> 1.12"}]
end``````

then run `mix deps.get`.

## usage Usage

``````five_eur         = Money.new(500, :EUR)             # %Money{amount: 500, currency: :EUR}
ten_eur          = Money.add(five_eur, five_eur)    # %Money{amount: 10_00, currency: :EUR}
hundred_eur      = Money.multiply(ten_eur, 10)      # %Money{amount: 100_00, currency: :EUR}
ninety_nine_eur  = Money.subtract(hundred_eur, 100) # %Money{amount: 99_00, currency: :EUR}
shares           = Money.divide(ninety_nine_eur, 2) # [%Money{amount: 4950, currency: :EUR}, %Money{amount: 4950, currency: :EUR}]

Money.equals?(five_eur, Money.new(500, :EUR)) # true
Money.zero?(five_eur);                        # false
Money.positive?(five_eur);                    # true

Money.Currency.symbol(:USD)                   # \$
Money.Currency.symbol(Money.new(500, :AFN))   # ؋
Money.Currency.name(Money.new(500, :AFN))     # Afghani

Money.to_string(Money.new(500, :CNY))         # ¥ 5.00
Money.to_string(Money.new(1_234_56, :EUR), separator: ".", delimiter: ",", symbol: false)
"1.234,56"
Money.to_string(Money.new(1_234_56, :USD), fractional_unit: false)  # "\$1,234"
Money.to_string(Money.new(1_234_50, :USD), strip_insignificant_zeros: true)  # "\$1,234.5"``````

### serialization-to-database-with-single-currency Serialization to database with single currency

Bring `Money` to your Ecto project. The underlying database type is `integer`

1. Set a default currency in `config.ex`:

``````config :money,
default_currency: :USD``````
2. Create migration with integer type:

``````create table(:jobs) do
end``````
3. Create schema using the `Money.Ecto.Amount.Type` Ecto type (don't forget run `mix ecto.migrate`):

``````schema "jobs" do
field :amount, Money.Ecto.Amount.Type
end``````
4. Save to the database:

``````iex(1)> Repo.insert %Job{amount: Money.new(100, :USD)}
[debug] QUERY OK db=90.7ms queue=0.1ms
INSERT INTO "jobs" ("amount","inserted_at","updated_at") VALUES (\$1,\$2,\$3) RETURNING "id" [100, {{2019, 2, 12}, {7, 29, 8, 589489}}, {{2019, 2, 12}, {7, 29, 8, 593185}}]
{:ok,
%MoneyTest.Offers.Job{
amount: %Money{amount: 100, currency: :USD},
id: 1,
inserted_at: ~N[2019-02-12 07:29:08.589489],
updated_at: ~N[2019-02-12 07:29:08.593185]
}}``````
5. Get from the database:

``````iex(2)> Repo.one(Job, limit: 1)
[debug] QUERY OK source="jobs" db=1.8ms
SELECT j0."id", j0."amount", j0."inserted_at", j0."updated_at" FROM "jobs" AS j0 []
%MoneyTest.Offers.Job{
amount: %Money{amount: 100, currency: :USD},
id: 1,
inserted_at: ~N[2019-02-12 07:29:08.589489],
updated_at: ~N[2019-02-12 07:29:08.593185]
}``````

### serialization-to-postgresql-with-multiple-currency Serialization to PostgreSQL with multiple currency

`Money.Ecto.Composite.Type` Ecto type represents serialization of `Money.t` to PostgreSQL Composite Types with saving currency.

1. Create migration with custom type:

``````def up do
execute """
CREATE TYPE public.money_with_currency AS (amount integer, currency varchar(3))
"""
end

def down do
execute """
DROP TYPE public.money_with_currency
"""
end``````
2. Then use created custom type(`money_with_currency`) for money field:

``````def change do
alter table(:jobs) do
end
end``````
3. Create schema using the `Money.Ecto.Composite.Type` Ecto type (don't forget run `mix ecto.migrate`):

``````schema "jobs" do
field :price, Money.Ecto.Composite.Type
end``````
4. Save to the database:

``````iex(1)> Repo.insert %Job{price: Money.new(100, :JPY)}
[debug] QUERY OK db=7.7ms
INSERT INTO "jobs" ("price","inserted_at","updated_at") VALUES (\$1,\$2,\$3) RETURNING "id" [{100, "JPY"}, {{2019, 2, 12}, {8, 7, 44, 729114}}, {{2019, 2, 12}, {8, 7, 44, 729124}}]
{:ok,
%MoneyTest.Offers.Job{
id: 6,
inserted_at: ~N[2019-02-12 08:07:44.729114],
price: %Money{amount: 100, currency: :JPY},
updated_at: ~N[2019-02-12 08:07:44.729124]
}}``````
5. Get from the database:

``````iex(2)> Repo.one(Job, limit: 1)
[debug] QUERY OK source="jobs" db=1.4ms
SELECT j0."id", j0."price", j0."inserted_at", j0."updated_at" FROM "jobs" AS j0 []
%MoneyTest.Offers.Job{
id: 6,
inserted_at: ~N[2019-02-12 08:07:44.729114],
price: %Money{amount: 100, currency: :JPY},
updated_at: ~N[2019-02-12 08:07:44.729124]
}``````

### serialization-to-database-json-with-multiple-currency Serialization to database (JSON) with multiple currency

`Money.Ecto.Map.Type` Ecto type represents serialization of `Money.t` to map(JSON) with saving currency.

1. Create migration with map type:

``````def change do
alter table(:jobs) do
end
end``````
2. Create schema using the `Money.Ecto.Map.Type` Ecto type (don't forget run `mix ecto.migrate`):

``````schema "jobs" do
field :price, Money.Ecto.Map.Type
end``````
3. Save to the database:

``````iex(1)> Repo.insert %Job{price: Money.new(100, :JPY)}
[debug] QUERY OK db=4.6ms
INSERT INTO "jobs" ("price","inserted_at","updated_at") VALUES (\$1,\$2,\$3) RETURNING "id" [%{"amount" => 100, "currency" => "JPY"}, {{2019, 2, 26}, {9, 40, 14, 381721}}, {{2019, 2, 26}, {9, 40, 14, 381730}}]
{:ok,
%MoneyTest.Offers.Job{
id: 9,
inserted_at: ~N[2019-02-26 09:40:14.381721],
price: %Money{amount: 100, currency: :JPY},
updated_at: ~N[2019-02-26 09:40:14.381730]
}}``````
4. Get from the database:

``````iex(8)> Repo.one(Job, limit: 1)
[debug] QUERY OK source="jobs" db=2.0ms
SELECT j0."id", j0."price", j0."inserted_at", j0."updated_at" FROM "jobs" AS j0 []
%MoneyTest.Offers.Job{
id: 10,
inserted_at: ~N[2019-02-26 09:40:45.205076],
price: %Money{amount: 100, currency: :JPY},
updated_at: ~N[2019-02-26 09:40:45.205084]
}``````

### money-sigils Money.Sigils

``````# Sigils for Money
import Money.Sigils

iex> ~M[1000]USD
%Money{amount: 1000, currency: :USD}

# If you have a default currency configured (e.g. to GBP), you can do
iex> ~M[1000]
%Money{amount: 1000, currency: :GBP}``````

### money-currency Money.Currency

``````# Currency convenience methods
import Money.Currency, only: [usd: 1, eur: 1, afn: 1]

iex> usd(100_00)
%Money{amount: 10000, currency: :USD}
iex> eur(100_00)
%Money{amount: 10000, currency: :EUR}
iex> afn(100_00)
%Money{amount: 10000, currency: :AFN}

Money.Currency.symbol(:USD)     # \$
Money.Currency.symbol(afn(500)) # ؋
Money.Currency.name(afn(500))   # Afghani
Money.Currency.get(:AFN)        # %{name: "Afghani", symbol: "؋"}``````

### phoenix-html-safe Phoenix.HTML.Safe

Bring `Money` to your Phoenix project. If you are using Phoenix, you can include money objects directly into your output and they will be correctly escaped.

``<b><%= Money.new(12345,67, :GBP) %></b>``

## configuration Configuration

You can set a default currency and default formatting preferences as follows:

``````config :money,
default_currency: :EUR,
separator: ".",
delimiter: ",",
symbol: false,
symbol_on_right: false,
symbol_space: false,
fractional_unit: true,
strip_insignificant_zeros: false,
code: false,
minus_sign_first: true,
strip_insignificant_fractional_unit: false``````

Then you don’t have to specify the currency.

``````iex> amount = Money.new(1_234_50)
%Money{amount: 123450, currency: :EUR}
iex> to_string(amount)
"1.234,50"``````

Here is another example of formatting money:

``````iex> amount = Money.new(1_234_50)
%Money{amount: 123450, currency: :EUR}
iex> Money.to_string(amount, symbol: true, symbol_on_right: true, symbol_space: true)
"1.234,50 €"``````

### custom-currencies Custom Currencies

In some cases we can need to add not common currencies, like crypto currencies or others. In order to add your own currencies you have to add them in the config file following this format:

``````config :money,
custom_currencies: [
BTC: %{name: "Bitcoin", symbol: "₿", exponent: 8},
GCS: %{name: "Galactic Credit Standard", symbol: "gcs", exponent: 0}
]``````

## troubleshooting Troubleshooting

### validating-amount-in-ecto-changeset Validating amount in Ecto changeset

When using the `Money.Ecto.Amount.Type` type, it may seem that a simple value validation should work, for example:

``````schema "jobs" do
field :amount, Money.Ecto.Amount.Type
end

def changeset(struct, params \\ %{}) do
struct
|> cast(params, [:amount])
|> validate_number(:amount, [greater_than: 0])
end``````

But this kind of validation will not work, since under the hood `Money.Ecto.Amount.Type` has the structure `%Money{amount: ..., currency: ...}`. To validate the data in this case, we recommend adding custom validation that matches your logic.

Example:

``````def changeset(struct, params \\ %{}) do
struct
|> cast(params, [:amount])
|> validate_money(:amount)
end

defp validate_money(changeset, field) do
validate_change(changeset, field, fn
_, %Money{amount: amount} when amount > 0 -> []
_, _ -> [amount: "must be greater than 0"]
end)
end``````

### lack-of-precision-when-using-money-parse Lack of precision when using `Money.parse`

Sometimes you need to work with large numbers (for example, cryptocurrencies) and `Float` precision is not enough. In this case it is better to use Decimal package. Money already has support for Decimal and you just need to add it to your project dependencies.