02-HowToCreateALoader.md

How to Create a Loader

Creating a loader is nearly identical to that of the Symfony Config component, with the difference being added support for Wise features.

• File Based Loader
• Other Loader

---

File Based Loader

To create a file-based loader, you need to extend the AbstractFileLoader class. The AbstractFileLoader class enabled support for global parameters and importing from other configuration resources. The following is an example simple loader for CSV files:

class CsvFileLoader extends Herrera\Wise\Loader\AbstractFileLoader
{
    public function supports($resource, $type = null)
    {
        return (is_string($resource)
            && ('csv' === strtolower(pathinfo($resource, PATHINFO_EXTENSION))))
            && ((null === $type) || ('csv' === $type));
    }

    protected function doLoad($resource, $type = null)
    {
        $fp = fopen($resource, 'r');
        $data = array();

        while (false !== ($row = fgetcsv($fp))) {
            if ((1 === count($row)) && (null === $row[0])) {
                continue;
            }

            $data[$row[0]] = $row[1];
        }

        fcloses($fp);

        return $data;
    }
}

Other Loader

For resources that are not files, you will need to implement these interfaces:

• Herrera\Wise\Resource\ResourceAwareInterface - For caching support
• Herrera\Wise\WiseAwareInterface - For global parameters support
• Symfony\Component\Config\Loader\LoaderInterface - For basic loading

Implementing the first two interfaces flags your class as having support for caching and global parameters. Your class will actually need to make use of the resource collector and Wise instance, which will be set when your class is set as the Wise loader. In the AbstractFileLoader class provided by the library, this is already handled for you.