readers.md

Plum is a data processing pipeline that helps you to write structured, reusable and well tested data processing code.

---

Index Workflow Readers Writers Filters Converters Extensions

---

You read data using an object that implements ReaderInterface. This interface extends \IteratorAggregate and \Countable interfaces and therefore you need to implement the getIterator() and count() methods.

Table of Contents

• Adding Readers
• Default Readers
• Custom Readers
• PHP 5.5 and Generators

Adding Readers

Readers are different than all other pipeline elements you can add to a workflow because you don't add them to the workflow, but pass them to the workflows process() method which starts processing the read items.

use Plum\Plum\Reader\ArrayReader;

$reader = new ArrayReader([2, 3, 5, 7, 11]);

$workflow->process($reader);

Instead of an instance of ReaderInterface you can also pass an array that contains multiple instances of ReaderInterface to process().

use Plum\Plum\Reader\ArrayReader;

$reader1 = new ArrayReader([2, 3, 5, 7, 11]);
$reader2 = new ArrayReader([101, 103, 107, 109, 113]);

$workflow->process([$reader1, $reader2]);

Default Readers

The core Plum package contains ArrayReader.

ArrayReader

The Plum\Plum\Reader\ArrayReader feeds the elements of an array to the workflow. In addition to the methods required by ReaderInterface it provides a getData() methods that returns the full array.

use Plum\Plum\Reader\ArrayReader;

$reader = new ArrayReader(['Stark', 'Lannister', 'Targaryen', ...]);
$reader->getData(); // -> ['Stark', 'Lannister', 'Targaryen', ...]

Custom Readers

As mentioned in the introduction ReaderInterface extends IteratorAggregate and Countable and readers therefore have to implement the getIterator() and count() methods.

use Plum\Plum\Reader\ReaderInterface;

class CollectionReader implements ReaderInterface
{
    private $collection = [];

    public function add($item)
    {
        $this->collection[] = $item;
    }

    public function getIterator()
    {
        return new ArrayIterator($this->collection);
    }
    
    public function count()
    {
        return count($this->collection);
    }
}

PHP 5.5 and Generators

If you are using PHP 5.5+ the getIterator() method can also return a generator.

public function getIterator()
{
    foreach ($this->collection as $item) {
        yield $item;
    }
}

---

Index Workflow Readers Writers Filters Converters Extensions