Accessor formatting causes 'A non-numeric value encountered' error on numeric operations

[swiftalker]

Laravel Version

12.6.0

PHP Version

8.3.19

Database Driver & Version

SQL Server 2017

Description

When using an accessor method to format a numeric attribute (e.g., cash) in the model, the numeric value becomes a string. This causes issues when performing numeric operations like increment() or decrement() on that attribute.

This issue occurs because formatting the numeric value inside the accessor transforms it into a string, preventing any arithmetic operations from being executed correctly. Specifically, the increment() method fails when the attribute is formatted as a string, resulting in a A non-numeric value encountered error.

Steps To Reproduce

1. Create a model (e.g., User) with a numeric attribute, for example, cash.

2. Define an accessor to format the cash attribute:

   public function getCashAttribute()
   {
       return Number::format($this->attributes['cash'], maxPrecision: 2);
   }

3. Add the necessary casting and fillable properties to the model:

   Migration:

   public function up()
   {
       Schema::table('partners', function (Blueprint $table) {
           $table->decimal('cash', 15, 2)->default(0);
       });
   }

   Model:

   protected $fillable = [
       'cash',
       'point',
       // other attributes
   ];
   
   protected function casts(): array
   {
       return [
           'cash' => 'decimal:15,2',
           'point' => 'decimal:15,2',
           // other casted attributes
       ];
   }

4. Attempt to increment the cash attribute using increment():

   $user->increment('cash', 10.2);

5. The error A non-numeric value encountered will be thrown because the value of cash is now a string after formatting in the accessor.

[macropay-solutions]

https://www.php.net/manual/en/migration71.other-changes.php

That is just a warning that would become exception is E_ALL if used as error reporting.

To avoid issues like this bcmath can be used in this line

framework/src/Illuminate/Database/Eloquent/Model.php

Line 983 in b5a8ea6

: $this->{$column} + ($method === 'increment' ? $amount : $amount * -1);

We had to hack this in our cruFd lib because when dealing with decimals, php + is not as accurate as bcmath so we refreshed the value from db (which can handle decimals like bcmath).

The other error is starting here

framework/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

Line 1469 in b5a8ea6

return (string) BigDecimal::of($value)->toScale($decimals, RoundingMode::HALF_UP);

and throws here
https://github.com/brick/math/blob/fc7ed316430118cc7836bf45faff18d5dfc8de04/src/BigDecimal.php#L671

So, the lib is misused.

https://github.com/brick/math/blob/fc7ed316430118cc7836bf45faff18d5dfc8de04/src/BigDecimal.php#L29C1-L34C33

    /**
     * The scale (number of digits after the decimal point) of this decimal number.
     *
     * This must be zero or more.
     */
    private readonly int $scale;

Here you can see how the lack of typed params bytes larave's ASS on this one

    /**
     * Return a decimal as string.
     *
     * @param  float|string  $value
     * @param  int  $decimals
     * @return string
     */
    protected function asDecimal($value, $decimals)
    {
        try {
            return (string) BigDecimal::of($value)->toScale($decimals, RoundingMode::HALF_UP);
        } catch (BrickMathException $e) {
            throw new MathException('Unable to cast value to a decimal.', previous: $e);
        }
    }

[swiftalker]

When using casts to set attributes as either float or decimal, I'm encountering different errors based on the type cast being used.

Scenario 1: Using float casting:

protected function casts(): array
{
    return [
        'email_verified_at' => 'datetime',
        'password' => 'hashed',
        'point' => 'float',
        'cash' => 'float',
    ];
}

This works, but when I perform operations on cash, it triggers the following error:

WARNING  A non-numeric value encountered in vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 981.

This error occurs because the cash attribute is being treated as a string, despite being cast to float.

Scenario 2: Using decimal:15,2 casting:

protected function casts(): array
{
    return [
        'email_verified_at' => 'datetime',
        'password' => 'hashed',
        'point' => 'float',
        'cash' => 'decimal:15,2',
    ];
}

In this case, I get the following error:

TypeError  Brick\Math\BigDecimal::toScale(): Argument #1 ($scale) must be of type int, string given, called in vendor/laravel/framework/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php on line 1469.

Steps to Reproduce:

1. Set up a model with the casts property using either float or decimal for the cash attribute.
2. Try performing operations on the cash attribute (e.g., adding a number to it or modifying it).
3. Observe the error that appears when the operation is performed.

Expected Behavior:

1. When using float, the cash value should be treated as a numeric value, allowing mathematical operations without errors.
2. When using decimal:15,2, it should work with the precision expected for decimals without triggering the TypeError related to BigDecimal.

Possible Solution:

It seems that the underlying issue is with how the cash attribute is being managed when casted. For float, it should be treated as a numeric value consistently, and for decimal, the proper type handling should ensure that BigDecimal works with the correct scale (integer) and doesn't throw the type error.

[macropay-solutions]

@swiftalker you are using the cast wrong acc to documentation

https://laravel.com/docs/12.x/eloquent-mutators#attribute-casting

But still the fact that the framework does not cast the explode[1] to int can be considered a bug.

Solution

            case 'decimal':
                return $this->asDecimal($value, explode(':', $this->getCasts()[$key], 2)[1]);

replaced with

            case 'decimal':
                return $this->asDecimal($value, (int)(explode(':', $this->getCasts()[$key], 2)[1]));

[swiftalker]

@macropay-solutions

Thank you for the correction!

I think it is just like 'decimal:15,2'

I just following the documentation, where is the mistake in the typing?

[macropay-solutions]

'decimal:2'

in v8

[swiftalker]

It seems like there's an issue with the documentation. In Laravel 8, we used decimal: for casting, which made sense because it aligned with how we define it in migrations (e.g., DECIMAL(15,2)). But in Laravel 12, it’s now decimal:, which can be a bit confusing.

The thing is, the precision in casting actually refers to the scale (the number of digits after the decimal point), not the total number of digits. This could lead to some confusion, as we were used to thinking of precision as the total number of digits, just like in migrations.

It’d be great if the documentation could clarify (and example too!) this to avoid any confusion. 😅

[macropay-solutions]

A cast to int must be done there also, coupled with the documentation. If the cast would had been there you would had noticed you get 15 digits after decimal point.