Data Transfer Object (DTO)

Create

To create a DataTransferObject create the class and use public properties.

use DataTransferObject\DataTransferObject;

class Employee extends DataTransferObject
{
    public string $name;
    public string $email;
    public ?Employee $reportsTo;
    public int $age;
    public bool $active = true;

    /**
     * @var \App\DataTransferObject\Employee[] $subordinates
     */
    public array $subordinates = [];
}

Then to set the data

$employee = new Employee();
$employee->name = 'sarah';

You can also mass set the properties using an array when constructing the argument. Note this only sets, does not convert or extract, see fromArray

 $sarah = new Employee([
            'name' => 'Sarah',
            'email' => 'sarah@example.com',
            'reportsTo' => $claire
        ]);

Build

When you use the DataTransferObject constructor, it simply sets the values that you are providing, however when you need to convert data and cast types, you can use the fromArray method.

The fromArray extracts relevant data and it:

1. casts built in types bool, int, string, float etc
2. will create a DataTransferObject, DateTime or any other object that has a __set_state magic method.

It will only extract fields defined in the DataTransferObject and will only throw an error, if after extracting data, a property on the DataTransferObject was not initialized.

For example, related DataTransferObjects such as belongsTo and hasMany will be marshalled. For hasMany to work create an array and set the DocBlock definition like below:

class Employee extends DataTransferObject
{
    public string $name;
    public string $email;
    public ?Employee $reportsTo;

    /**
     * @var \App\DataTransferObjects\Employee[] $subordinates
     */
    public array $subordinates = [];
}

To use the fromArray method

 $employee = Employee::fromArray([
    'name' => 'Sarah',
    'email' => 'sarah@example.com',
    'reportsTo' => [
        'name' => 'Claire',
        'email' => 'claire@example.com',
    ],
    'subordinates' => [
        [
            'name' => 'Jon',
            'email' => 'jon@example.com'
        ]
    ]
]);

Converting to an Array

To convert the DataTransferObject and any nested objects to an array if the object has an toArray method or does not have a __toString method.

$employee->toArray();

Serialization / Deserialization

The default serialization method is JSON, for a different method, e.g. XML you can override the serialize and deserialize methods. Only public properties will be used in the serialization and therefore deserialization process.

To string

To convert a DataTransferObject to a string.

$employee->toString();

From string

To convert a string to a DataTransferObject

$employee = Contact::fromString(
    '{"name":"Jon","company":"Snow Enterprises","email":"jon@example.com","age":33,"unsubscribed":false}'
);

Initialize Hook

When the DataTransferObject is constructed it will call initialize method if it is available, this is a hook incase you need to override the constructor.

Exception Handling

If you try to set or get a property that does not exist, a RuntimeException will be thrown.

Resources

• Data Transfer Object (DTO) - Martin Fowler
• Data Transfer Object - Wikipedia