Using PHP explode() to parse multi-part error messages

Question

I am dealing with a system which sends any unexpected errors back to me in a string, for example:

Error Type - Database
Error Message - Error Executing Database Something is wrong.
Error Detail - [Macromedia][SQLServer JDBC Driver][SQLServer]Incorrect syntax near '1'.

Now to create a better UI I am expected to deal with these errors, so I thought about using explode(), and found this user's response in the PHP Manual which helped me delimit the results with two delimiters instead of just one:

Then I needed to get a little deeper into the code because I wanted $key => $val pairs, so I came across this answer on StackOverflow.

Then I combined both and came across this solution:

function multiexplode ($delimiters,$string) {
 $ready = str_replace($delimiters, $delimiters[0], $string);
 list($err_typ, $err_typ_cont,
 $err_mess, $err_mess_cont,
 $err_det, $err_det_cont) = explode($delimiters[0], $ready);
 $result[ trim($err_typ) ] = trim($err_typ_cont);
 $result[ trim($err_mess) ] = trim($err_mess_cont);
 $result[ trim($err_det) ] = trim($err_det_cont);
 return $result;
}

Then I call the function like this:

 multiexplode(array("-", PHP_EOL), $errorMessage)

The response seems to be exactly what I needed:

Array
(
 [Error Type] => Database
 [Error Message] => Error Executing Database Something is wrong.
 [Error Detail] => [Macromedia][SQLServer JDBC Driver][SQLServer]Incorrect syntax near '1'.
)

---

My question comes with PHP's best practices, and if there would be a more reliable or a more efficient approach I could take into solving this problem?

• Sᴀᴍ Onᴇᴌᴀ: which delimeters are you using? I presume not the same from that PHP UCN (i.e. ",",".","|",":")
• sam: @SamOnela No, I am using "-", PHP_EOL The - to separate key from value, and PHP_EOL to create new item from string's new line

Answer 1

A couple of thoughts:

• This function is designed to only deal with a very sepcific use case - parsing a formatted error string. For that reason I would recommend changing the function name to be more representative of what is actually happening. Perhaps something like parseErrorString() or similar.
• Since you are dealing with a very specific use case here, why would you require the caller to pass in the delimiters? This function should fully encapsulate all the parsing logic.
• Using an array for return, seems odd, particularly since you have spaces in your key names. I would consider returning a stdClass or similar object with type, message, detail properties.
• Though not strictly required, I would consider using regular expressions here, as I think that can clean things up as well as allow the solution to be less fragile to changes in the string format.
• Using PHP_EOL as line break may be fragile. PHP_EOL is good for working with strings within same environment, but may fail if your application is running in a different environment than the environment your string is produced in.
• Your function assumes happy path execution. What if you get a poorly/unexpectedly formatted string? Perhaps you are validating this string somewhere else, but if not, you should do it here in your function.

A refactoring, with these thoughts in mind, might yield something like the following:

function parseErrorString($string) {
 if(empty($string) || !is_string($string)) {
 throw new InvalidArgumentException('Non-zero length string expected');
 }
 $lines = preg_split('/\R/', $string);
 $error = array_reduce(
 $lines,
 function (&$err, $line) {
 $regex = '/^Error (Type|Message|Detail) - (.*)$/';
 $matches = [];
 $result = preg_match($regex, $line, $matches);
 if ($result !== 1) {
 // no match. Is this an error condition?
 // at the very least, do nothing
 return $err;
 }
 $err->{strtolower($matches[1])} = $matches[2];
 return $err;
 },
 new stdClass();
 );
 return $error;
}

• sam: I am getting this error: Fatal error</b>: Cannot use object of type stdClass as array on line <b>268</b>
• Mathieu Guindon: @Samuel code in CR answers isn't meant to be taken as-is (reviewers don't even have to supply code), it's meant to illustrate a point.
• sam: Okay, I was just trying to build off the code you offered; I was testing it to see how it would work.
• Mike Brant: @Samuel Sorry have been writing too much javascript lately I guess, and had syntax error.
• sam: It's alright... I've never been a javascript guy...

Answer 2

This task seems simple enough to me. I only recommend that you limit the explosion performed on each line, then it won't matter if the delimiter is duplicated later in the line. Clean, reliable, fast.

Code: (Demo)

function parseErrorMessage($string) {
 foreach(explode(PHP_EOL, $string) as $line){ // split on end of lines
 list($label,$message)=explode(' - ',$line,2); // limit the explosion to 2 elements
 $result[$label]=$message; // preserve using first half and second half of line
 }
 return $result;
}
$string ="Error Type - Database
Error Message - Error Executing Database Something is wrong.
Error Detail - [Macromedia][SQLServer JDBC Driver][SQLServer]Incorrect syntax near '1'.";
print_r(parseErrorMessage($string));

Output:

Array
(
 [Error Type] => Database
 [Error Message] => Error Executing Database Something is wrong.
 [Error Detail] => [Macromedia][SQLServer JDBC Driver][SQLServer]Incorrect syntax near '1'.
)

---

If you are concerned that your error messsage substring may contain line breaks, then regex is better suited.

The code to follow will break the string into a 1-dimensional array of alternating labels and messages before pairing them with array_chunk() then assigning them as your desired key-value pairs with array_combine().

Code: (Demo)

function parseErrorMessage($string) {
 $pairs=array_chunk(preg_split('/\R*(Error \w+) - /',$string,NULL,PREG_SPLIT_NO_EMPTY|PREG_SPLIT_DELIM_CAPTURE),2);
 return array_combine(array_column($pairs,0),array_column($pairs,1));
}
$string ="Error Type - Database
Error Message - Error Executing Database Something is wrong.
Error Detail - [Macromedia]
[SQLServer JDBC Driver]
[SQLServer]Incorrect syntax near '1'.";
var_export(parseErrorMessage($string));

Output:

array (
 'Error Type' => 'Database',
 'Error Message' => 'Error Executing Database Something is wrong.',
 'Error Detail' => '[Macromedia]
[SQLServer JDBC Driver]
[SQLServer]Incorrect syntax near \'1\'.',
)

Answer 3

Per your comment:

I am using "-", PHP_EOL The - to separate key from value, and PHP_EOL to create new item from string's new line

This makes me worry about the cases where one of the lines contains a hyphen (i.e. -), which would yield an incomplete string - see this playground example for an illustration.

Mike's answer is good. I agree the name could be made specific for parsing the error message, and that regular expressions could be utilized, though explode() should suffice.

function parseErrorMessage ($string) {
 $lines = explode(PHP_EOL, $string);
 return array_reduce($lines, function($result, $line) {
 $lineParts = explode(' - ', $line);
 $key = array_shift($lineParts);
 $result[trim($key)] = join(' - ', $lineParts);
 return $result; 
 }, []);
}

This can be demonstrated in this playground example.