Laravel Value Object

Allows you to create value objects in eloquent models, in the form of casts that are then stored in the database, or to represent the data as an object.

Installation
Usage
License

Installation

To get the latest version of Laravel Value Object package, simply require the project using Composer:

$ composer require isakzhanov-r/laravel-value-object

Instead, you can, of course, manually update the dependency block require in composer.json and run composer update if you want to:

{
    "require-dev": {
        "isakzhanov-r/laravel-value-object": "^1.0"
    }
}

Usage

Creating

To use Value Object, you need to create a class that will inherit from the abstract ValueObject class

use IsakzhanovR\ValueObject\ValueObject;

class Temperature extends ValueObject 
{
    ....
}

The ValueObject class has mandatory methods for implementation, transform and rules

use IsakzhanovR\ValueObject\ValueObject;

class Temperature extends ValueObject 
{
    protected function transformInput($value)
    {
        return $value;
    }

    protected function rules(): array
    {
        return [];
    }
}

The ValueObject inheritor class has two methods for creating an object, via new FooValueObject($value, $key) and via a static call to the create function

  $temperature = new Temperature(25);

  $temperature = Temperature::create(25);

if the key is not passed to the function argument, it is generated automatically from the class name

 {
  #key: "temperature"
  -value: 25
 }

 echo $temperature;  // 25

Validation

The data in ValueObject must be valid for this, the Illuminate\Validation\ValidatesWhenResolvedTrait validation trait is used. The same trait is used in FormRequest. To define rules for the validator, use the rules method

use IsakzhanovR\ValueObject\ValueObject;

class Temperature extends ValueObject 
{
    ....

    protected function rules(): array
    {
        return [
            $this->key => ['required','numeric','between:-100,100']
        ];
    }
}

If ValueObject is array, then its value is validated in the same way:

use IsakzhanovR\ValueObject\ValueObject;

class Address extends ValueObject 
{
    ....

    protected function rules(): array
    {
        return [
            $this->key              => ['required', 'array'],
            $this->key . '.country' => ['required', 'string'],
            $this->key . '.city'    => ['required', 'string'],
            $this->key . '.street'  => ['required', 'string'],
            $this->key . '.number'  => ['required', 'numeric'],
        ];
    }
}

For custom error messages, use the messages method:

use IsakzhanovR\ValueObject\ValueObject;

class Temperature extends ValueObject 
{
    ....

    protected function messages(): array
    {
        return [
            $this->key.'.between' => 'The range of tmp temperatures should be from -100 to +100',
        ];
    }
}

You can also declare an authorize method that returns true or false.

Use in Model

To use ValueObject in Eloquent models, you do not need to add anything, just specify it in $casts.

Let's say you have an Eloquent Whether model . You may want to apply transformations to this field or get a value in degrees Celsius, Fahrenheit or Kelvin. If you use this type of field in multiple models, copying and pasting getAttribute functions can be difficult.

Such valuable items become very useful. Let's see how to do this. First, we created a weather model that will have a temperature field brought to the temperature value object.

use Illuminate\Database\Eloquent\Model;

class Weather extends Model
{
    ....
    
    protected $casts = [
        ...
        'temperature' => Temperature::class, 
        ...
      ];
    
    ....
}

We will add the following methods to the temperature object

use IsakzhanovR\ValueObject\ValueObject;

class Temperature extends ValueObject 
{
    ....

    public function inCelsius()
    {
        return (float) $this->value();
    }

    public function inKelvin()
    {
        return (float) $this->value() + 273.15;
    }

    public function inFahrenheit()
    {
        return (float) $this->value() * 1.8 + 32;
    }
}

Objects with a value are stored in the database as a prime number and can be used as follows:

    $weather = new Weather;
    $weather->temperature = new Temperature(9);
  
    echo $weather->temperature;                 // Prints '9'
    echo $weather->temperature->value();        // Prints '9'
    echo $weather->temperature->inKelvin();     // Prints 282.15
    echo $weather->temperature->inFahrenheit(); // Prints 48.2

To write to the model, you must use an instance of ValueObject:

    $weather = new Weather;
    $weather->temperature = new Temperature(9);
    $weather->save()
    
//Or

    $temperature = new Temperature(9);
    $weather = Weather::create(compact('temperature'));
    
//Or
    $weather = Weather::create(Temperature::create(9)->toDTO());

You may also use Accessors and Mutators, just like in Eloquent Models.

class Weather extends Model
{
    ....
    
    protected $casts = [
        ...
        'temperature' => Temperature::class, 
        ...
      ];
    
    protected $appends = ['celsius','kelvin','fahrenheit'] 
    
    public function getCelsiusAttribute()
    {
        return $this->temperature->inCelsius();
    }
    
    public function getKelvinAttribute()
    {
        return $this->temperature->inKelvin();
    }
    
    public function getFahrenheitAttribute()
    {
        return $this->temperature->inFahrenheit();
    }
}

Transform data

Data transformation is intended for minor manipulations with data, for example, clearing unnecessary characters. This method is performed before validation. The transformInput function is also executed in the Eloquent model with both get and set methods

use IsakzhanovR\ValueObject\ValueObject;

class Title extends ValueObject 
{
    protected function transformInput($value)
    {
        $value = trim(e($value));

        return mb_ucfirst(Str::lower($value));
    }
    
    ...
}

Serialize and unserialize

Sometimes objects with a value may not be so simple and may require several fields instead of one. Let's say we have a User model with an address field that contains the country, city, street and house number, this field in the database is of the json type. Then we could define the User model as we did before:

class User extends Model
{
    protected $casts = [
        'address' => Address::class
    ];
}

Then we will be able to define the address value object as follows:

use IsakzhanovR\ValueObject\ValueObject;

class Address extends ValueObject 
{
    protected function transformInput($value)
    {
        return $value;
    }

    protected function rules(): array
    {
        return [
            $this->key              => ['required', 'array'],
            $this->key . '.country' => ['required', 'string'],
            $this->key . '.city'    => ['required', 'string'],
            $this->key . '.street'  => ['required', 'string'],
            $this->key . '.number'  => ['required', 'numeric'],
        ];
    }
}

In order to write data, you need to convert an array to a json string and, accordingly, when reading this string from the database, you need to convert it back to an array, for this we will need the serialize and unserialize static methods. These methods are executed only if they are declared.

class Address Extends ValueObject
{
    ....
    
    public static function unserialize($value)
    {
        return json_decode($value, true);
    }

    public static function serialize($value)
    {
        return json_encode($value);
    }
    
    ....
}

License

This package is released under theMIT License.

isakzhanov-r/laravel-value-object