Parse String Array of regex values within PHP

Question

The combination of the way I'm working with this is complex and I can't find any reference on how to accomplish it.

I'm allowing the user to store a representation of an array of regex values in the database (MySql) like so:

'["/^\d{5}([\-]?\d{4})?$/i", "/^([ABCEGHJKLMNPRSTVXY]\d[ABCEGHJKLMNPRSTVWXYZ])\ {0,1}(\d[ABCEGHJKLMNPRSTVWXYZ]\d)$/i"]'

Now in my PHP code I read it into a variable $val and it looks like this:

'["/^\\d{5}([\\-]?\\d{4})?$/i", "/^([ABCEGHJKLMNPRSTVXY]\\d[ABCEGHJKLMNPRSTVWXYZ])\\ {0,1}(\\d[ABCEGHJKLMNPRSTVWXYZ]\\d)$/i"]'

and trying to leverage JSON to decode it into an actual array:

$val = '{"unq":'.$val.'}';
$obs = json_decode($val);
return $obs->unq;

Problem is, I get Notice: Trying to get property of non-object in... on $obs->unq;

I'm guessing this has to do with the way the regex is being stored, but I'm not certain. Too many wasted hours on this, thanks for your help.

Answer 1

It seem's your parser (mysqli_real_escaped_string or something else) does not escape any of structural characters expected in a json string (except unicode chars i guess)

As you can read in the JSON RFC about strings escaping slashes (forward or backward) should be escaped !

"The representation of strings is similar to conventions used in the C family of programming languages"

Then, you can use addcslashes to escape it:

$reg = addcslashes($reg, chr(0x5c)); // hex notation, beware of '\\'
$out = '{"unq":'.$reg.'}';
$out = json_decode($out);

Hint

You should use native debug functions like var_dump and json error handler to ensure where error occur from:

var_dump(json_last_error_msg(), $out);
return $out->unq;

in error way:

string(12) "Syntax error"
NULL

solved:

string(8) "No error"
object(stdClass)#1 (1) {
  ["unq"]=>
  array(2) {
    [0]=>
    string(23) "/^\d{5}([\-]?\d{4})?$/i"
    [1]=>
    string(86) "/^([ABCEGHJKLMNPRSTVXY]\d[ABCEGHJKLMNPRSTVWXYZ])\ {0,1}(\d[ABCEGHJKLMNPRSTVWXYZ]\d)$/i"
  }
}

Storage

I dont know about your purpose, but there is another way to help on this king of storage. You can also serialize a true array of regex

// before saving
$patterns = serialize
([
    "/^\d{5}([\-]?\d{4})?$/i",
    "/^([ABCEGHJKLMNPRSTVXY]\d[ABCEGHJKLMNPRSTVWXYZ])\ {0,1}(\d[ABCEGHJKLMNPRSTVWXYZ]\d)$/i",
]);

// usage out of mysql, unserialize do the tricks
return $patterns = unserialize($sqlressource["patterns"]);