Pipeline

The data pipeline allows you to configure how data objects are constructed from a payload. In the previous chapter we saw that a data object created from a payload will be first normalized into an array. This array is passed into the pipeline.

The pipeline exists of multiple pipes which will transform the normalized data into a collection of property values which can be passed to the data object constructor.

By default, the pipeline exists of the following pipes:

• AuthorizedDataPipe checks if the user is authorized to perform the request
• MapPropertiesDataPipe maps the names of properties
• ValidatePropertiesDataPipe validates the properties
• DefaultValuesDataPipe adds default values for properties when they are not set
• CastPropertiesDataPipe casts the values of properties

Each result of the previous pipe is passed on into the next pipe, you can define the pipes on an individual data object as such:

class SongData extends Data
{
    public function __construct(
        // ...
    ) {
    }

    public static function pipeline(): DataPipeline
    {
        return DataPipeline::create()
            ->into(static::class)
            ->through(AuthorizedDataPipe::class)
            ->through(MapPropertiesDataPipe::class)
            ->through(ValidatePropertiesDataPipe::class)
            ->through(DefaultValuesDataPipe::class)
            ->through(CastPropertiesDataPipe::class);
    }
}

Each pipe implements the DataPipe interface and should return a Collection of properties:

interface DataPipe
{
    public function handle(mixed $payload, DataClass $class, Collection $properties): Collection;
}

The handle method has several arguments:

• payload the non normalized payload
• class the DataClass object for the data object more info
• properties the key-value properties which will be used to construct the data object

When using a magic creation methods, the pipeline is not being used (since you manually overwrite how a data object is constructed). Only when you pass in a request object a minimal version of the pipeline is used to authorize and validate the request.

##Preparing data for the pipeline

Sometimes you need to make some changes to the payload after it has been normalized, but before they are sent into the data pipeline. You can do this using the prepareForPipeline method as follows:

class SongMetadata
{
    public function __construct(
        public string $releaseYear,
        public string $producer,
    ) {}
}

class Song extends Data
{
    public function __construct(
        public string $title,
        public SongMetadata $metadata,
    ) {}
    
    public static function prepareForPipeline(Collection $properties) : Collection
    {
        $properties->put('metadata', $properties->only(['release_year', 'producer']));
        
        return $properties;
    }
}

Now it is possible to create a data object as follows:

$song = Song::from([
    'title' => 'Never gonna give you up',
    'release_year' => '1987',
    'producer' => 'Stock Aitken Waterman',
]);

##Extending the pipeline within your data class

Sometimes you want to send your payload first through a certain pipe without creating a whole new pipeline, this can be done as such:

class Song extends Data
{
    public static function pipeline(): DataPipeline
    {
        return parent::pipeline()->firstThrough(GuessCasingForKeyDataPipe::class);
    }
}