Fallback Overkill? - php

Question

I have had no formal teaching in coding and was hoping if anyone could tell me if I was being to cautious with my code?
// Insert info to the db
if ($stmt = $db_connect->prepare("INSERT INTO db (col1, col2) VALUES (?, ?)")) {
if(!$stmt->execute([$val1, $val2])) {
exit("1:Faild to create deal");
}
// Get last id
$id = (int)$db_connect->lastInsertId();
$stmt->closeCursor();
} else { exit("0:Faild to create deal"); }
// Create the folder
if(!mkdir("folder/folder".$id)) {
if($stmt = $db_connect->prepare("DELETE FROM db WHERE id=?")) {
if(!$stmt->execute([$id])) {
exit("1:Faild to create the directory -> Faild to remove the row from the database");
}
exit("Faild to create the directory");
}
exit("0:Faild to create the directory -> Faild to remove the row from the database");
}
I repeat the create folder statement 2 more times with the same layout. It's just repeatable code that looks to be overkill.
Note: The package I have with my host only has MyISAM tables so I can't use Rollback.
If something fails I want to undo everything that has passed.
Could someone please give me some guidance to best practices or am I doing it right?

Answer 1

i re-structured and extended your code plus added a bit of simple error handling by using exceptions.
first you should set your PDO error handling to exception mode:
$db_connect->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
then i have capsulated your actions into functions, which you can put into a separate file and include it, or even nest them into classes:
/*** FUNCTIONS ***/
// insert info to the db
function dbInsertInfo($db_connect, $val1, $val2)
{
$stmt = $db_connect->prepare("INSERT INTO db (col1, col2) VALUES (?, ?)");
$stmt->execute([$val1, $val2]));
}
//-------------------------------
// get the last insert id
function dbGetId($db_connect)
{
$id = (int)$db_connect->lastInsertId();
$stmt->closeCursor();
return $id;
}
//-------------------------------
// delete db-entry
function dbDeleteId($db_connect, $id)
{
$stmt = $db_connect->prepare("DELETE FROM db WHERE id=?");
$stmt->execute([$id]);
}
//-------------------------------
// create the folder
function createFolder($id)
{
if(!mkdir("folder/folder".$id)) throw new Exception("Failed to create the directory");
}
//-------------------------------
then here is your procedure with all the try{ } catch{ } sections for the error handling by exceptions:
/* PROCEDURE */
// 01 | try to insert into db
try
{
dbInsertInfo($db_connect, $val1, $val2);
}
catch(PDOException $e)
{
//if exception thrown, do not continue the script:
echo "Unable to insert into DB: ".$e->getMessage();
exit();
}
//-------------------------------
// 02 | try to get last insert id
$id = false;
try
{
$id = dbGetId($db_connect);
}
catch(PDOException $e)
{
//if exception thrown, do not continue the script:
echo "Unable to get last insert id from DB: ".$e->getMessage();
exit();
}
//-------------------------------
// 03 | try to create folder // if it fails -> try to delete db entry
try
{
createFolder($id);
}
catch(Exception $e)
{
// if exception caught, try to remove the corresponding DB entry:
echo $e->getMessage();
echo "<br />";
echo "trying to remove DB entry now";
// try to delete db entry
try
{
dbDeleteId($db_connect, $id);
}
catch(PDOException $e)
{
//if exception thrown, do not continue the script:
echo "Unable to delete from DB: ".$e->getMessage();
exit();
}
}
//-------------------------------
/* Everything worked fine if you get to this point of the code*/
just might seem like an technical overkill for you now, but i think it's much more structured and better to read it, once you got into it. plus, it's only divided into 3 steps.