Dealing with currency in Laravel

Salih — Sun, 22 May 2022 12:17:03 +0000

Most applications have to deal with currencies in some way or another and unfortunately it isn't always straightforward due to database limitations.

Among a few different solutions to how to store currency in the database my choice always is storing it in cents as an integer. (if you prefer another way turn around now)

Storing in cents solves many of our problems like dealing with floats and such, however, creates a new challenge, remembering what state your variables are in. The amount of times I would by mistake store a currency in USD format instead or converted cents to cents again is way too damn high. Also converting constantly back and forth gets quite old quickly and don't we all hate writing the same thing over and over again?
Let me demonstrate what I am talking about.

$currency = 1;
$currencyInCents = $currency * 100;
$someFeeRate = 0.12;

$currencyInCentsWithFee = $currencyInCents * $someFeeRate;

$model = Model::create([
  'amount' => $currencyInCentsWithFee
]);

// $model->amount - 
//I already lost what format this was in may be I have a bad memory

return response()->json([
  'currency' => '$'.number_format($model->amount / 100, 2)
]);

Did you realise how many times I had to write "inCents" within my variables?
Of course I am exaggerating a little bit with this example but once there more levels of calculations things get worse and worse if you have been there, you know.

There is also a good chance that the next developer within the project is going to do something completely different to what I just did.

As a solution we came up with a simple package for currency:
https://github.com/Kodeas/currency

$currency = Currency::fromUsd(1);

$someFeeRate = 0.12;

$currencyWithFee = Currency::fromCents($currency->inCents() * $someFeeRate);

//model has currency as a cast of Currency::class
$model = Model::create([
  'amount' => $currencyWithFee
]);

//$model->amount - 
//this is now an instance of Currency::class so it is in whatever format you wish

return response()->json([
  'currency' => $model->amount->toReadable('$')
]);

The currency class is used as a cast to standardise currency operations in your entire app, regardless of who is the developer writing it. Your currency will always be stored in cents and you will never forget what state your currency was during your operations.

I also appreciate you might be sceptical of adding a package for something so simple therefore, I also wrote about how it was made so you can also create one of your own.

There it is, nice and quick solution to most of your currency issues while using Laravel.

Please feel free to contribute to the package if you have any additions and show some ❤️ with a like if this helped you.

Creating casts like Carbon in Laravel

Salih — Sat, 21 May 2022 15:06:00 +0000

Most of us using Laravel have used Carbon for date casting since it comes with the package and also simply because it is just awesome.

What if you wanted to create a similar experience for your own custom casts?

So, here is a short guide how to achieve something similar:
(I will use Currency as an example however you can apply this to anything)

Firstly, we will need our trusty type class with a simple constructor and a a couple static initiators (just like Carbon::parse('05/05/22')). Also it would be great to have some getters like toUsd() and toCents() for ease of use.

class Currency
{
    public function __construct(int $amountInCents)
    {
        $this->amountInCents = $amountInCents;
    }

    public static function fromCents(int $amountInCents):Currency
    {
        return new self($amountInCents);
    }

    public static function fromUsd(float|int $amount): Currency
    {
        return new self($amount * 100);
    }

    public function toUsd(): float|int
    {
        return $this->amountInCents / 100;
    }

    public function toCents(): int
    {
        return $this->amountInCents;
    }
}

Now we are able to initiate our class using Currency::fromCents(100), I prefer to store all my currencies in cents since floats are weird in database level but let's not get into the nitty gritty here.

Secondly, we will utilize Laravel's custom casts feature for this

class Currency implements CastsAttributes
{
    /**
     * Cast the given value.
     *
     * @param  Model  $model
     * @param  string  $key
     * @param  mixed  $value
     * @param  array  $attributes
     * @return CurrencyType
     */
    public function get($model, string $key, mixed $value, array $attributes): CurrencyType
    {
        return CurrencyType::fromCents($value);
    }

    /**
     * @param  Model  $model
     * @param  string  $key
     * @param  CurrencyType|string|float|int  $value
     * @param  array  $attributes
     * @return int
     * @throws InvalidCurrencyFormatException
     */
    public function set($model, string $key, mixed $value, array $attributes): int
    {
        if (!($value instanceof CurrencyType)) {
            $currency = CurrencyType::class;
            $type = getType($value);
            throw new InvalidCurrencyFormatException("The given value must be $currency. $type was given.");
        }

        return $value->toCents();
    }

Please have a look at the docs for more info about this step

We now have our shiny Currency cast that we can use on any model like:

'money_column' => Currency::class,

I am sure we are all aware of how magical🪄 casts are but let me outline we achieved here.

Whenever you want to store this column you can just use a Currency object and just send it over to the database and it will automatically to store it in cents without questions.
Whenever you fetch this record from the database, it will automatically be in the format of Currency and you can use the getters as you wish.

Now you can stop at this point and call it a day, I wouldn't blame you at all but we are here to have the full Carbon style cast experience. So lets go a little bit further, you won't regret it I am sure (I hope you won't).

Our next step is a beautiful detail that most of us take for granted about Carbon.(at least I did until recently)

When a Carbon object is passed to front-end (blade or json) it magically turns into a formatted string instead of an Object.

Let's add this to our Currency class.

use JsonSerializable;

class Currency implements JsonSerializable
{
    protected int $amountInCents;

    public function __construct(int $amountInCents)
    {
        $this->amountInCents = $amountInCents;
    }

    public static function fromCents(int $amountInCents): Currency
    {
        return new self($amountInCents);
    }

    public static function fromUsd(float|int $amount): Currency
    {
        return new self($amount * 100);
    }

    public function toUsd(): float|int
    {
        return $this->amountInCents / 100;
    }

    public function toCents(): int
    {
        return $this->amountInCents;
    }

    public function toReadable(): string
    {
        return number_format($this->toUsd(), 2);
    }

    public function jsonSerialize(): string
    {
        return $this->toReadable();
    }

    public function __toString(): string
    {
        return $this->toReadable();
    }
}

JsonSerializable is a native php interface for more info have a look at php docs

Using _JsonSerializable interface makes sure whenever you class is going through a json_encode() the jsonSerialize( function is used and Laravel almost always runs any response through json_encode() within the ResponseFactory class.
I have to admit it took me way too long to figure this out

I also added the __toString() method so if at any point you would like to use this class as a string you wouldn't need any other helpers.

$currency = Currency::fromUsd(1);
json_encode($currency); //"1.00"
echo $currency; //"1.00"

...
return response()->json(['amount' => $currency]) //would be "1.00" on the front-end

I think that is just elegant, all my worries about storing currency in cents or usd are gone.

If you have any other use-cases for something like this I would love to see it in the comments, I am sure there must be many.

Thanks for reading, drop a ❤️ if you made it all the way down here.

Also let me know in the comments if you have any further improvements to this or found this useful or just plain hate the idea 😬

Forem: Salih

Dealing with currency in Laravel

Creating casts like Carbon in Laravel