class-gv-source.php

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<?php
namespace GV;

/** If this file is called directly, abort. */
if ( ! defined( 'GRAVITYVIEW_DIR' ) ) {
    die();
}

/**
 * The \GV\Source class.
 *
 * Contains the source for \GV\Field values.
 *
 * For example, "gravityview" fields, like custom content, are sourced
 *  from the \GV\View and its \GV\Field configuration. While "gravityforms"
 *  fields are sourced from \GV\Entry instances.
 */
abstract class Source {
    
    /**
     * @var string BACKEND_INTERNAL The backend identifier for special GravityView data sources
     *  like custom content and the like. Not really a form, but a source nevertheless.
     */
    const BACKEND_INTERNAL = 'internal';

    /**
     * @var string BACKEND_GRAVITYFORMS The backend identifier for special GravityView data sources
     *  like custom content and the like. Not really a form, but a source nevertheless.
     */
    const BACKEND_GRAVITYFORMS = 'gravityforms';

    /**
     * @var string The identifier of the backend used for this source.
     *
     * @see Constant backend identifiers above and \GV\Source subclasses.
     *
     * @api
     * @since 2.0
     */
    public static $backend = null;

    /**
     * Get a \GV\Field instance by ID.
     *
     * Accepts a variable number of arguments, see implementations.
     *
     * @return \GV\Field|null A \GV\Field instance.
     */
    public static function get_field( /** varargs */ ) {
        gravityview()->log->error( '{source}::get_field not implemented in {source}', array( 'source' => get_called_class() ) );
        return null;
    }
}