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Date: Sat, 27 Feb 2021 16:44:16 +0000
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Subject: Re: [PHP-DEV] [RFC]: Change Default mysqli Error Mode
From: rowan.collins@gmail.com (Rowan Tommins)

On 27/02/2021 16:23, Kamil Tekiela wrote:
> I don't see why this would be such an issue. If the code fails for any
> reason then an error is produced. The error might be surprising, but it is
> not something that would cause problems.


Just addressing this argument, not the proposal itself, a function 
throwing an exception that previously failed silently absolutely could 
cause problems.

Consider this code:

function get_product($product_id) {
     $sql = "Select * From products Where product_id = '" . 
$dbWrapper->escape($product_id) . "'";
     return $dbWrapper->runQuery($sql);
}

If product_id is actually an integer column, this function is 
technically broken: given a non-integer input, it will produce an error 
in the database. However, with lax error handling, the calling code will 
simply treat this as the product not existing, and handle it gracefully.

If $dbWrapper->runQuery suddenly starts throwing exceptions, functions 
that were inadvertently relying on this behaviour will start failing, 
possibly with an uncaught exception propagating to the user.

The exception is certainly pointing out a real bug, and the function can 
easily be fixed once the problem is spotted, but the change has a real 
negative impact on the application.


To be clear, I am not saying I agree or disagree with this particular 
proposal. I note that the user could in this example update their DB 
wrapper to set the error mode explicitly, or to catch exceptions. I just 
wanted to show that "it only happens on error" doesn't mean the impact 
is zero.

Regards,

-- 
Rowan Tommins
[IMSoP]