Method's optional parameter, when passed as string, becomes an array - php

Question

Tl;dr: at the bottom
Setup:
I have a cron job that calls a PHP script to handle some Backend tasks. For simplicity, the cron job redirects all output to a log file. Because this matters to my actual question found below, here's the sanitized format of the cron job:
15 4 * * * php /usr/local/bin/myScript.php >> /home/$USER/scriptLogs/myScript.log 2>&1
I'm new-ish to OOP and I'm being tasked with learning it as I go, and for myScript.php, I'm doing some data imports that require querying the DB to validate the data prior to its import and I'm supposed to log every transaction. We recently moved from 5.6 to 7.2 and part of task at hand is to use 7.2's new features as we refactor.
The refactor itself is to take all of the duplicated code and move it to classes to obey the DRY principle.
Previously, it looked something like this:
<?php namespace CronJobs
use PDO;
use Exception;
class JobAt415 {
private function getDBconnection()
{
// connects to a DB through environment variable set in a config file
return $db;
}
public function query1($parameter1, $parameter2, $inclusionParameter)
{
$sql = "SELECT " . $parameter1 . ", ". $parameter2 . " FROM `foo`.`bar` WHERE " . $inclusionParmeter " IS NOT NULL;";
try
{
$db = $this->getDBconnection();
echo '[' . strftime("%c") . '] Running query 1' . PHP_EOL;
$resultDictionary = $db->query($sql)->fetchall(PDO::FETCH_KEY_PAIR)
return $resultDictionary;
}
catch (Exception $e)
{
echo '[' . strftime("%c") . '] ERRORS ' . PHP_EOL;
echo $e->getMessage();
return null;
}
}
public function query2($parameter1, $parameter3)
{
$sql = "SELECT " . $parameter1 . " FROM `foo`.`bar` WHERE " . $parameter3 " > 0;";
try
{
$db = $this->getDBconnection();
echo '[' . strftime("%c") . '] Running query 1' . PHP_EOL;
$resultDictionary = $db->query($sql)->fetchall()
return $resultArray;
}
catch (Exception $e)
{
echo '[' . strftime("%c") . '] ERRORS ' . PHP_EOL;
echo $e->getMessage();
return null;
}
}
}
Post-Refactor:
<?php namespace CronJobs
use PDO;
use Exception;
Class DbConnectionFactory {
protected $dbConnection;
public function __construct()
{
$this->dbConnection = $this->createConnection();
}
public function runQuery($sql, ...$queryDescriptor)
{
try
{
$descriptor = $queryDescriptor ? (string) $queryDescriptor : $sql;
echo '[' . strftime("%c") . '] Running query ' . "$descriptor" . PHP_EOL;
$resultPending = $this->dbConnection->query($sql);
echo '[' . strftime("%c") . '] Query successful.' . PHP_EOL;
return $resultPending;
}
catch (Exception $e)
{
echo '[' . strftime("%c") . '] ERRORS ' . PHP_EOL;
echo $e->getMessage();
return null;
}
}
public function runQueryFetchDictionary($sql, ...$queryDescriptor)
{
$description = (string) $queryDescriptor;
$fetchAll = $this->runQuery($sql, $description)->fetchall(PDO::FETCH_KEY_PAIR);
return $fetchAll;
}
// In the JobAt415 class
private function runQuery1()
{
$sql = 'SELECT `parameter1`, `parameter2` FROM `foo`.`bar` WHERE `baz` IS NOT NULL;';
$description = 'p1, p2 :: baz != NULL';
$p1Dictionary = $this->db->runQueryFetchDictionary($sql, $descripton); // $this->db is an instantiation of the DbConnectionFactory class
So, now I just pass the SQL query as a parameter and a description of what is being queried to be echoed to the log, and I don't have 19 try/catch blocks in the code or a bunch of duplicated code that I've removed from this example.
Unfortunately, as I'm stepping through the code with XDebug, the optional parameter $queryDescriptor is being converted from a string to an array. I've tried multiple ways of passing it, casting it, and/or defining it and get the same result: $queryDescriptor is an array. At one point, casting it to a string returned the value of "Array".
When I checked the PHP website, I found this:
Note:
The behaviour of an automatic conversion to array is currently undefined.
Emphasis mine.
I don't want any conversion. So, how do I prevent this? Does anyone see what I'm missing? Why doesn't the $sql string get converted to an array but the $queryDescriptor always get converted?
Tl;dr:
Why is my string now an array?

Answer 1

Because by adding a parameter like ...$queryDescriptor you tell PHP that there can be endless parameters. This is because of the ... in front of the variable name. That's why PHP changes the type to an array.
Otherwise how could you handle the number of possibly thousand of parameters?
https://secure.php.net/manual/en/functions.arguments.php#functions.variable-arg-list
//You tell PHP that there can be a variable number of parameters by adding '...' in front of the variable name
function foo(...$bar) {
//You get an array holding all the passed parameters
foreach($bar as $arg) {
//By stepping through it you get all the parameters
echo $arg;
}
}
Or of course you can get the parameters by their indexes.
$bar[0]; //returns the first passed parameter