Issue with regexp to retrieve log messages

Question

I'm having a little issue with regexp, i know this isn't directly a magento issue though.

My goal is to get a sub printing of magento logs in the admin.

To do so, I've created the following method

public function getLog($logfile,$nbLine = null){
    $nbCharPerLineApproximative = 100;
    $nbLine = $nbLine == null?$this->getNbLineToPrint():$nbLine;
    $contents = null;
    try {
        $path = $this->directoryList->getPath('var').'/log/'.$logfile ;
        $fileSubContent = substr($this->driverFile->fileGetContents($path),- $nbLine * $nbCharPerLineApproximative);
        var_dump($fileSubContent);

        $re = '/\[\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}][[:print:]]{1,}/';
        preg_match_all($re, $fileSubContent, $contents, PREG_SET_ORDER, 0);
        var_dump($contents);
    } catch (FileSystemException $e) {
        var_dump($e->getMessage());
    }
    return $contents;
}

$fileSubContent, will get all the data perfectly. But the regex is messing with accent.

As an exemple the regexp will match

Paypal a rejete le paiement.

But it will only match

Paypal a rejet

if the real sentence is

Paypal a rejeté le paiement.

The main goal being to retrieve all data "logs by logs" and not just line by line

[2021-08-10 12:21:14] main.ERROR: Unable to unserialize value. [] [] [2021-08-10 12:25:45] main.ERROR: Paypal a rejeté la demande. [] []

Answer 1

Since you are saying 'log by log', I assume you want to create a regex to split like this:

[2021-08-10 12:21:14] main.ERROR: Unable to unserialize value. []
[2021-08-10 12:25:45] main.ERROR: Paypal a rejeté la demande. []

Then when you want to use the date and message, you may be able to do this:

(?<date>\[\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}])(?<message>.+?)(\[\])

Use preg_match_all as you already are, but now you have two benefits:

1. Accents splitting correctly (removed :print:)
2. Date and Message split for each item.

preg_match_all('/(?<date>\[\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}])(?<message>.+?)(\[\])/', $fileSubContent, $contents);

Then loop through each $contents and access the date and message keys, so ignore the indexed (0-n) items. This will mean indexed item $contents['message'][0] and $contents['date'][0] should be for the same row.

Test output

I removed the accent from the word to see if there are anything different, results look the same:

0   =>  array(4
0   =>  [2021-08-10 12:21:14] main.ERROR: Unable to unserialize value. []
1   =>  [2021-08-10 12:25:45] main.ERROR: Paypal a rejeté la demande. []
2   =>  [2021-08-10 12:21:14] main.ERROR: Unable to unserialize value. []
3   =>  [2021-08-10 12:25:45] main.ERROR: Paypal a rejete la demande. []
)
**date**    =>  array(4
0   =>  [2021-08-10 12:21:14]
1   =>  [2021-08-10 12:25:45]
2   =>  [2021-08-10 12:21:14]
3   =>  [2021-08-10 12:25:45]
)
1   =>  array(4
0   =>  [2021-08-10 12:21:14]
1   =>  [2021-08-10 12:25:45]
2   =>  [2021-08-10 12:21:14]
3   =>  [2021-08-10 12:25:45]
)
**message** =>  array(4
0   =>   main.ERROR: Unable to unserialize value. 
1   =>   main.ERROR: Paypal a rejeté la demande. 
2   =>   main.ERROR: Unable to unserialize value. 
3   =>   main.ERROR: Paypal a rejete la demande. 
)
2   =>  array(4
0   =>   main.ERROR: Unable to unserialize value. 
1   =>   main.ERROR: Paypal a rejeté la demande. 
2   =>   main.ERROR: Unable to unserialize value. 
3   =>   main.ERROR: Paypal a rejete la demande.