src/properties/class-papi-property.php
protected function render_hidden_html() {
		$slug = $this->get_option( 'slug' );

		if ( substr( $slug, - 1 ) === ']' ) {
			$slug = substr( $slug, 0, - 1 );
			$slug = papi_get_property_type_key( $slug );
			$slug .= ']';
		} else {
			$slug = papi_get_property_type_key( $slug );
		}

		$slug          = papify( $slug );
		$options       = $this->get_options();
		$property_json = base64_encode( papi_maybe_json_encode( $options ) );

		papi_render_html_tag( 'input', [
			'data-property' => strtolower( $this->get_option( 'type' ) ),
			'name'          => $slug,
			'type'          => 'hidden',
			'value'         => $property_json
		] );
	}
protected function render_hidden_html() {
		$slug = $this->get_option( 'slug' );

		if ( substr( $slug, - 1 ) === ']' ) {
			$slug = substr( $slug, 0, - 1 );
			$slug = papi_get_property_type_key( $slug );
			$slug .= ']';
		} else {
			$slug = papi_get_property_type_key( $slug );
		}

		$slug          = papify( $slug );
		$options       = $this->get_options();
		$property_json = base64_encode( papi_maybe_json_encode( $options ) );

		papi_render_html_tag( 'input', [
			'data-property' => strtolower( $this->get_option( 'type' ) ),
			'name'          => $slug,
			'type'          => 'hidden',
			'value'         => $property_json
		] );
	}
Output hidden input field that cointains which property is used.