Error handling confusion

Yii 2.0 General Discussions
1

How to write code to handle an error here?

$when = new DateTimeImmutable();
$next = $when->modify($difference);

Where $difference is a string such as “+ 10 seconds”. It’s hard to write validation for $difference so it makes sense to just try the modify() and test the result.

In naked PHP I would test for false return value from modify(). But in a Yii environment, I also need to be prepared for yii\base\ErrorException. So I could do something like

try {
    $next = $when->modify($difference);
} catch (\yii\base\ErrorException $ignore) {
    $next = false;
}
if ($next === false) {
    // do the fallback behavior
}

Is this a reasonable approach, assuming I want the code to work with or without Yii’s error handler being involved?

2

If you don’t need to notify the user about the error and just want to give a fallback value, then you don’t have to worry about the exception handling:.

$when = new DateTimeImmutable(); 
$next = $when->modify($difference);
if ($next === false) {
    $next = $when;
}

If you need to notify the user, then you could write like this:

$when = new DateTimeImmutable(); 
$next = $when->modify($difference);
if ($next === false) {
    throw new yii\base\UserException("Invalid difference specified.");
}

There will be no dedicated try-catch block for this, since the exception will be handled by Yii and the user will be informed of the parameter error by an error view.

Please check the guide
https://www.yiiframework.com/doc/guide/2.0/en/runtime-handling-errors

Or, if the “difference” comes from the user input, I would not use error handling mechanism but would write an inline-validator instead.

public function rules()
{
    return [
        ['diff', function ($attribute, $params, $validator) {
            $when = new DateTimeImmutable(); 
            $next = $when->modify($this->$attribute);
            if ($next === false) {
                $this->addError($attribute, 'Invalid difference specified.');
            }
        }],
    ];
}

Check the following section of the guide:
https://www.yiiframework.com/doc/guide/2.0/en/input-validation#creating-validators

3

I don’t want to notify the error. I just want to use modify() to test the input and handle invalid input, like your validator example. (My input is a batch file so I don’t use a validator but the technique of testing the return value is the same.)

There’s a difficulty that I didn’t elaborate before: PHP issues a warning when modify() is called with invalid argument (in addition to modify() returning false) and Yii’s error handler escalates the warning into a yii\base\ErrorException.

Alt text

So I wrote the complicated code around modify() that I showed to cope with Yii’s exception and the return value. But I don’t like it and wanted to check with other Yii users about alternatives.

4

I see.
I think I would do the same as you, then.
Or I would change the PHP error reporting level temporarily.

$errorlevel = error_reporting();
error_reporting($errorlevel &~E_WARNING);
//...code that uses modify()
error_reporting($errorlevel);
5

Both are unpleasant. The latter option is more portable across different possible error handlers.