PHP: Converting WP_ERROR to Exception - php

Question

I'm currently struggling to add error handling for the following case. An error is raise when a $db database is trying to write into it when it has --read-only access. This causes the following error on WP Engine.
WordPress database error INSERT command denied to user 'readonly'#'xx.xxx.xx.xx' for table 'responses' for query INSERT INTO `responses`
I wan't for this error to not break the application so I'm trying to add error handling. However, when I raise an Exception is not being caught. I know that WP_ERROR are different, so how to I convert an WP_ERROR to an exception?
function drools_request($data, $uid) {
try {
$db = _get_db();
$insertion = $db->insert("requests", [
"uid" => $uid,
"data" => json_encode($data),
]);
if( is_wp_error($insertion) ) {
throw new \Exception('Error writing to the database:');
}
}
catch(\Exception $e)
{
echo 'Error writing to the database: ', $e->getMessage(), "\n";
}
}
This is what I tried so far without success. Here I check for is_wp_error() if this condition is true I throw an exception. However, this did not work. I thought this is how one would go about handling a WP_ERROR, but I wonder if there is another way to handle this type of errors. Here is the full class:
<?php
namespace StatCollector;
function drools_request($data, $uid) {
try {
$db = _get_db();
$insertion = $db->insert("requests", [
"uid" => $uid,
"data" => json_encode($data),
]);
if( is_wp_error($insertion) ) {
throw new \Exception('Error writing to the database:');
}
}
catch(\Exception $e)
{
echo 'Error writing to the database: ', $e->getMessage(), "\n";
}
}
function drools_response($response, $uid) {
try {
$db = _get_db();
$insertion = $db->insert("responses", [
"uid" => $uid,
"data" => json_encode($response),
]);
if( is_wp_error($insertion) ) {
throw new \Exception('Error writing to the database:');
}
}
catch(\Exception $e)
{
echo 'Error writing to the database: ', $e->getMessage(), "\n";
}
}
function results_sent($type, $to, $uid, $url = null, $message = null) {
try {
$db = _get_db();
$insertion = $db->insert("messages", [
"uid" => $uid,
"msg_type" => strtolower($type),
"address" => $to,
"url" => $url,
"message" => $message
]);
if( is_wp_error($insertion) ) {
throw new \Exception('Error writing to the database:');
}
}
catch(\Exception $e)
{
echo 'Error writing to the database: ', $e->getMessage(), "\n";
}
}
function peu_data($staff, $client, $uid) {
try {
if (empty($uid)) {
return;
}
$db = _get_db();
if (! empty($staff)) {
$insertion = $db->insert("peu_staff", [
"uid" => $uid,
"data" => json_encode($staff)
]);
}
if( is_wp_error( $insertion ) ) {
throw new \Exception('Error writing to the database:');
}
if (! empty($client)) {
$insertion = $db->insert("peu_client", [
"uid" => $uid,
"data" => json_encode($client)
]);
}
if( is_wp_error($insertion) ) {
throw new \Exception('Error writing to the database:');
}
}
catch(\Exception $e){
echo 'Error writing to the database: ', $e->getMessage(), "\n";
}
}
function response_update() {
$uid = $_POST['GUID'];
$url = $_POST['url'];
$programs = $_POST['programs'];
if (empty($uid) || empty($url) || empty($programs)) {
wp_send_json(["status" => "fail","message" => "missing values"]);
return wp_die();
}
try {
$db = _get_db();
$insertion = $db->insert("response_update", [
"uid" => $uid,
"url" => $url,
"program_codes" => $programs
]);
wp_send_json(["status" => "ok"]);
wp_die();
if( is_wp_error($insertion) ) {
throw new \Exception('Error writing to the database.');
}
}
catch(\Exception $e)
{
echo 'Error writing to the database: ', $e->getMessage(), "\n";
}
}

Answer 1

wpdb::insert does not return WP_Error on error. On error it returns boolean false. The error printing is done inside of wpdb::query itself, but you can disable that by setting suppress_errors to true, and then gracefully get the previous error with the last_error property.
$db->suppress_errors(true);
//Note: If you still want to log the errors to your server log
//use $db->hide_errors(); instead.
$insertion = $db->insert("requests", [
"uid" => $uid,
"data" => json_encode($data),
]);
if( $insertion === false ) {
throw new \Exception('Error writing to the database: ' . $db->last_error);
}