Cache Buster
Bypass your website cache when loading a Gravity Forms form.
Read the WalkthroughCode
Filename: gw-cache-buster.php
<?php
/**
* Gravity Wiz // Gravity Forms // Cache Buster
* https://gravitywiz.com/cache-busting-with-gravity-forms/
*
* Bypass your website cache when loading a Gravity Forms form.
*
* Plugin Name: Gravity Forms Cache Buster
* Plugin URI: https://gravitywiz.com/cache-busting-with-gravity-forms/
* Description: Bypass your website cache when loading a Gravity Forms form.
* Author: Gravity Wiz
* Version: 0.6
* Author URI: https://gravitywiz.com
*/
class GW_Cache_Buster {
private $_args = array();
public function __construct( $args = array() ) {
// set our default arguments, parse against the provided arguments, and store for use throughout the class
$this->_args = wp_parse_args(
$args,
array(
'form_id' => false,
'field_id' => false,
)
);
// do version check in the init to make sure if GF is going to be loaded, it is already loaded
add_action( 'init', array( $this, 'init' ) );
}
public function init() {
// make sure we're running the required minimum version of Gravity Forms
if ( ! property_exists( 'GFCommon', 'version' ) || ! version_compare( GFCommon::$version, '1.8', '>=' ) ) {
return;
}
add_filter( 'gform_shortcode_form', array( $this, 'shortcode' ), 10, 3 );
add_filter( 'gform_save_and_continue_resume_url', array( $this, 'filter_resume_link' ), 15, 4 );
add_filter( 'gform_pre_replace_merge_tags', array( $this, 'replace_embed_url' ), 10, 4 );
add_action( 'gform_after_submission', array( $this, 'entry_source_url' ), 10, 2 );
add_action( 'wp_ajax_nopriv_gfcb_get_form', array( $this, 'ajax_get_form' ) );
add_action( 'wp_ajax_gfcb_get_form', array( $this, 'ajax_get_form' ) );
}
public function shortcode( $markup, $attributes, $content ) {
$atts = shortcode_atts(
array(
'id' => 0,
'cachebuster' => false,
),
$attributes
);
$form_id = $atts['id'];
if ( ! $this->is_cache_busting_applicable() ) {
return $markup;
}
$is_enabled = rgar( $atts, 'cachebuster' ) || gf_apply_filters( array( 'gfcb_enable_cache_buster', $form_id ), false, $form_id );
if ( ! $is_enabled ) {
return $markup;
}
add_filter( "gform_footer_init_scripts_filter_{$form_id}", array( $this, 'suppress_default_post_render_event' ), 10, 3 );
ob_start();
?>
<div id="gf-cache-buster-form-container-<?php echo $form_id; ?>" class="gf-cache-buster-form-container">
<div class="loader"></div>
<style type="text/css">
.gf-cache-buster-form-container { }
.loader,
.loader:before,
.loader:after {
border-radius: 50%;
width: 2.5em;
height: 2.5em;
-webkit-animation-fill-mode: both;
animation-fill-mode: both;
-webkit-animation: load7 1.8s infinite ease-in-out;
animation: load7 1.8s infinite ease-in-out;
}
.loader {
color: rgba( 0, 0, 0, 0.5 );
font-size: 10px;
margin: 0 auto 80px;
position: relative;
text-indent: -9999em;
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
-webkit-animation-delay: -0.16s;
animation-delay: -0.16s;
}
.loader:before,
.loader:after {
content: '';
position: absolute;
top: 0;
}
.loader:before {
left: -3.5em;
-webkit-animation-delay: -0.32s;
animation-delay: -0.32s;
}
.loader:after {
left: 3.5em;
}
@-webkit-keyframes load7 {
0%,
80%,
100% {
box-shadow: 0 2.5em 0 -1.3em;
}
40% {
box-shadow: 0 2.5em 0 0;
}
}
@keyframes load7 {
0%,
80%,
100% {
box-shadow: 0 2.5em 0 -1.3em;
}
40% {
box-shadow: 0 2.5em 0 0;
}
}
</style>
</div>
<?php
// Include original query parameters (with some exclusions) in the AJAX call to preserve dynamic population via query string.
$exclude_params = array( 'action', 'form_id', 'atts' );
$ajax_url = remove_query_arg( $exclude_params, add_query_arg( $_GET, admin_url( 'admin-ajax.php' ) ) );
// Still needed for the AJAX submission.
$ajax_params = array(
'action' => 'gfcb_get_form',
'form_id' => $form_id,
);
// Ensure AJAX parameters for GPNF are also correctly populated.
if ( class_exists( 'GPNF_Session' ) ) {
$ajax_params['gpnf_context'] = array(
'path' => esc_js( GPNF_Session::get_session_path() ),
);
}
$ajax_url = add_query_arg( $ajax_params, $ajax_url );
$lang = null;
if ( class_exists( 'Gravity_Forms_Multilingual' ) ) {
global $sitepress;
$lang = $sitepress->get_current_language();
}
?>
<script type="text/javascript">
( function ( $ ) {
var formId = '<?php echo $form_id; ?>';
$.post( '<?php echo $ajax_url; ?>', {
action: 'gfcb_get_form',
form_id: '<?php echo $form_id; ?>',
atts: <?php echo wp_json_encode( $attributes ); ?>,
form_request_origin: '<?php echo esc_js( GFCommon::openssl_encrypt( GFFormsModel::get_current_page_url() ) ); ?>',
lang: '<?php echo $lang; ?>'
}, function( response ) {
$( '#gf-cache-buster-form-container-<?php echo $form_id; ?>' ).html( response ).fadeIn();
if( window['gformInitDatepicker'] ) {
gformInitDatepicker();
}
// Initialize GPPA
// @todo Since we are not triggering the `gform_post_render` below, I'm not certain that we need this.
if( response.indexOf('GPPA') > -1 ) {
window.gform.doAction('gppa_register_form', formId);
}
// We probably don't need this since everything else should already be loaded by this point but since
// GF is using it as their standard for triggering the `gform_post_render` event, I figured we should follow suit.
gform.initializeOnLoaded( function() {
// Form has been rendered. Trigger post render to initialize scripts.
<?php
echo sprintf(
'gform.initializeOnLoaded(function() {%s});',
GFFormDisplay::post_render_script(
$form_id,
GFFormDisplay::get_current_page( $form_id )
) );
?>
} );
} );
} )( jQuery );
</script>
<?php
return ob_get_clean();
}
public function is_cache_busting_applicable() {
// POSTED and LOGGED-IN requests are not typically cached
return empty( $_POST ) || ! is_user_logged_in();
}
public function suppress_default_post_render_event( $form_string, $form, $current_page ) {
$searches = array(
"gform.initializeOnLoaded( function() { jQuery(document).trigger('gform_post_render', [{$form['id']}, {$current_page}]) } );",
"gform.initializeOnLoaded( function() {jQuery(document).trigger('gform_post_render', [{$form['id']}, {$current_page}]);gform.utils.trigger({ event: 'gform/postRender', native: false, data: { formId: {$form['id']}, currentPage: {$current_page} } });} );",
);
foreach ( $searches as $search ) {
$search = GFCommon::get_inline_script_tag( $search );
$form_string = str_replace( $search, '', $form_string );
}
if ( is_callable( 'GFFormDisplay::post_render_script' ) ) {
$post_render_script = GFFormDisplay::post_render_script( $form['id'], $current_page );
$post_render_script = preg_quote( $post_render_script, '/' ); // Escape special characters
$pattern = '/<script>\s*gform\.initializeOnLoaded\(\s*function\(\)\s*\{\s*(' . $post_render_script . ')\s*\}\s*\);\s*<\/script>/';
$form_string = preg_replace( $pattern, '', $form_string );
}
return $form_string;
}
public function ajax_get_form() {
$form_id = isset( $_POST['form_id'] ) ? absint( $_POST['form_id'] ) : 0;
if ( ! $form_id ) {
$form_id = isset( $_GET['form_id'] ) ? absint( $_GET['form_id'] ) : 0;
}
add_filter( 'gpasc_new_draft_form_path', function( $form_path, $form ) {
return rgpost( 'form_request_origin' )
? remove_query_arg( 'gf_token', GFCommon::openssl_decrypt( rgpost( 'form_request_origin' ) ) )
: $form_path;
}, 10, 2 );
/**
* Init scripts are output to the footer by default so they are not needed in the AJAX response. Some plugins
* deliberately output inline scripts alongside the form (see Nested Forms' `gpnf_preload_form` filter) but I
* haven't encountered a scenario where this is ideal when fetching the form via an AJAX request like we do here.
*
* Additionally, to support this change, we manually trigger the `gform_post_render` event after we've loaded
* the form markup from this AJAX response.
*
* Priority of this filter is set aggressively high to ensure it will take priority.
*/
add_filter( 'gform_init_scripts_footer', '__return_true', 987 );
add_filter( 'gform_form_tag_' . $form_id, array( $this, 'add_hidden_inputs' ), 10, 2 );
add_filter( 'gform_pre_render_' . $form_id, array( $this, 'replace_embed_tag_for_field_default_values' ) );
$atts = rgpost( 'atts' );
// GF expects an associative array for field values. Parse them before passing it on.
$field_values = wp_parse_args( rgar( $atts, 'field_values' ) );
// If `$_POST` is not an empty array GF 2.5 fails to select default values for checkbox fields. See HS#26188
$GLOBALS['GWCB_POST'] = $_POST;
$_POST = array();
gravity_form( $form_id, filter_var( rgar( $atts, 'title', true ), FILTER_VALIDATE_BOOLEAN ), filter_var( rgar( $atts, 'description', true ), FILTER_VALIDATE_BOOLEAN ), false, $field_values, true /* default to true; add support for non-ajax in the future */, rgar( $atts, 'tabindex' ) );
remove_filter( 'gform_form_tag_' . $form_id, array( $this, 'add_hidden_inputs' ) );
remove_filter( 'gform_pre_render_' . $form_id, array( $this, 'replace_embed_tag_for_field_default_values' ) );
die();
}
/**
* Since the form is loading admin-ajax.php, GFFormsModel::get_current_page_url() will return the wrong URL when
* saving and continuing.
*
* We need to replace the resume link with the page loading the AJAX form.
*
* @param string $resume_url The URL to be used to resume the partial entry.
* @param array $form The Form Object.
* @param string $resume_token The token that is used within the URL.
* @param string $email The email address associated with the partial entry.
*/
public function filter_resume_link( $resume_url, $form, $resume_token, $email ) {
if ( rgar( $_REQUEST, 'action' ) !== 'gfcb_get_form' ) {
return $resume_url;
}
$referer = rgar( $_SERVER, 'HTTP_REFERER' );
if ( ! $referer ) {
return $resume_url;
}
return add_query_arg( array( 'gf_token' => $resume_token ), $referer );
}
/**
* Replace `{embed_url}` merge tag for notifications, confirmations, etc.
*
* @param string $text The current text with merge tags.
* @param array $form The current form.
* @param array $entry The current entry.
* @param boolean $url_encode The URLs need to be encoded or not.
*
* @return string
*/
public function replace_embed_url( $text, $form, $entry, $url_encode ) {
// Check if the text contains the {embed_url} merge tag
if ( strpos( $text, '{embed_url}' ) !== false ) {
$origin = $this->get_form_request_origin();
if ( ! $origin ) {
return $text;
}
// Replace the {embed_url} merge tag with the original URL
$text = str_replace( '{embed_url}', $origin, $text );
}
return $text;
}
/**
* Append hidden inputs to store the entry url.
*
* @param array $entry The current entry.
* @param array $form The current form.
*/
function entry_source_url( $entry, $form ) {
$origin = $this->get_form_request_origin();
if ( ! $origin ) {
return;
}
GFAPI::update_entry_property( $entry['id'], 'source_url', $origin );
}
/**
* Replace {embed_url} and {embed_post} merge tag for field default values. We have to do this using gform_pre_render as
* gform_pre_replace_merge_tags is not called for field default values.
*
* @param array $form The current form.
*/
public function replace_embed_tag_for_field_default_values( $form ) {
foreach ( $form['fields'] as &$field ) {
$text = $field->defaultValue;
$origin = $this->get_form_request_origin();
$post_id = url_to_postid( $origin );
if ( strpos( $text, '{embed_url}' ) !== false ) {
if ( ! $origin ) {
continue;
}
$field->defaultValue = str_replace( '{embed_url}', $origin, $text );
}
preg_match_all( '/\{embed_post:(.*?)\}/', $text, $ep_matches, PREG_SET_ORDER );
if ( $ep_matches && $post_id ) {
$post = get_post( $post_id );
$post_array = GFCommon::object_to_array( $post );
foreach ( $ep_matches as $match ) {
$full_tag = $match[0];
$property = $match[1];
$value = $post_array[ $property ];
$text = str_replace( $full_tag, $value, $text );
}
$field->defaultValue = $text;
}
}
return $form;
}
/**
* Helper method to get the form request origin.
*/
public function get_form_request_origin() {
static $form_request_origin;
if ( $form_request_origin ) {
return $form_request_origin;
}
$origin = rgpost( 'gwcb_form_request_origin' );
$origin = $origin ?: rgpost( 'form_request_origin' );
$origin = $origin ?: rgars( $GLOBALS, 'GWCB_POST/form_request_origin' );
if ( $origin ) {
$form_request_origin = GFCommon::openssl_decrypt( $origin );
} else {
$form_request_origin = null;
}
return $form_request_origin;
}
/**
* Append hidden inputs to store the entry url.
*
* @param string $form_tag The form opening tag.
* @param array $form The current form.
*
* @return string
*/
public function add_hidden_inputs( $form_tag, $form ) {
if ( strpos( $form_tag, 'gwcb_form_request_origin' ) !== false ) {
return $form_tag;
}
$form_tag .= '<input type="hidden" value="' . esc_attr( rgars( $GLOBALS, 'GWCB_POST/form_request_origin' ) ) . '" name="gwcb_form_request_origin" />';
return $form_tag;
}
}
# Configuration
new GW_Cache_Buster();
# Enable Cache Buster on all forms.
//add_filter( 'gfcb_enable_cache_buster', '__return_true' );
# Enable Cache Buster on all forms with exceptions.
//add_filter( 'gfcb_enable_cache_buster', function( $should_enable, $form_id ) {
// if ( ! in_array( $form_id, array( 493, 124, 125 ) ) ) {
// $should_enable = true;
// }
// return $should_enable;
//}, 10, 2 );