WordPress \ Polylang : Adds "current" and "default" language merge tags for Gravity Forms

wp-gf-pll-merge_tags.php

<?php

if ( ! class_exists('Polylang') ) {
	return;
}

/**
 * Filter: Replace Polylang merge tags with their respective values
 *
 * @used-by Filter: GravityForms\'gform_replace_merge_tags'
 * @uses Polylang\pll_current_language()
 * @uses Polylang\pll_default_language()
 *
 * @param string  $text       The current text in which merge tags are being replaced.
 * @param array   $form       The current form.
 * @param array   $entry      The current entry.
 * @param boolean $url_encode Whether or not to encode any URLs found in the replaced value.
 * @param boolean $esc_html   Whether or not to encode HTML found in the replaced value.
 * @param boolean $nl2br      Whether or not to convert newlines to break tags.
 * @param string  $format     Default "html"; determines how the value should be formatted.
 */

function gf_pll_replace_language_merge_tags( $text, $form, $entry, $url_encode, $esc_html, $nl2br, $format )
{
	$merge_tag = '{pll_current_language}';

	if ( strpos( $text, $merge_tag ) === false || empty( $entry ) || empty( $form ) ) {
		return $text;
	}

	$text = str_replace( $merge_tag, pll_current_language(), $text );

	$merge_tag = '{pll_default_language}';

	if ( strpos( $text, $merge_tag ) === false || empty( $entry ) || empty( $form ) ) {
		return $text;
	}

	$text = str_replace( $merge_tag, pll_default_language(), $text );

	return $text;
}

add_filter( 'gform_replace_merge_tags', 'gf_pll_replace_language_merge_tags', 10, 7 );

/**
 * Action: Adds a JavaScript filter to add language merge tags using Polylang.
 *
 * Merge Tags:
 * - `{pll_current_language}`
 * - `{pll_default_language}`
 *
 * @used-by Action: GravityForms\'gform_admin_pre_render'
 *
 * @param array $form The current form to be filtered.
 */

function gf_pll_filter_merge_tags( $form )
{
?>
	<script>
		/**
		 * Filter: Adds language merge tags using Polylang to the Merge Tag drop-down in the admin.
		 *
		 * Ideally integrated through the PHP 'gform_admin_pre_render' action.
		 *
		 * Merge Tags:
		 * - `{pll_current_language}`
		 * - `{pll_default_language}`
		 *
		 * @link http://www.gravityhelp.com/documentation/gravity-forms/extending-gravity-forms/hooks/javascript/gform_merge_tags/
		 * @used-by Filter: GravityForms\'gform_merge_tags'
		 * 
		 * @param {array}   mergeTags         - The current merge tags
		 * @param {strign}  elementId         - The name of the current field. When selecting the Merge Tag
		 *                                      drop down on the Advanced tab of a form field, the value will
		 *                                      always be "field_default_value". The confirmation and notification
		 *                                      admin pages will return specific field names so you may target
		 *                                      adding a merge tag to a specific field.
		 * @param {string}  hideAllFields     - Indicates whether to include the "All Submitted Fields" choice
		 *                                      in the Merge Tag drop down.
		 * @param {array}   excludeFieldTypes - Indicates which field types should be ignored.
		 * @param {boolean} isPrepop          - Indicates whether to include form fields in the Merge Tag drop down.
		 * @param {string}  option            - Internal use by Gravity Forms.
		 * @param {object}  gfMergeTagsObj    - Reference to the MergeTags object.
		 */
		
		function gf_pll_add_merge_tags( mergeTags, elementId, hideAllFields, excludeFieldTypes, isPrepop, option, mergeTagsObj )
		{
			mergeTags['other'].tags.push({ tag: '{pll_current_language}', label: '<?php _e('Current Language', 'upa'); ?>' });
			mergeTags['other'].tags.push({ tag: '{pll_default_language}', label: '<?php _e('Default Language', 'upa'); ?>' });
		
			return mergeTags;
		}
		
		gform.addFilter( 'gform_merge_tags', 'gf_pll_add_merge_tags' );
	</script>
<?php

	return $form;
}

add_action( 'gform_admin_pre_render', 'gf_pll_filter_merge_tags' );