CODEWITHSUNDEEP
phpguid
Svetlozar Angelov
Svetlozar Angelov

Reputation: 21660

php - check for valid guid

I have a mssql database in which my primary keys are GUIDs. I am working on a web interface for inserting some data. I need a GUID, generated by php. I am using com_create_guid() function. So, before trying to insert I want to ensure that my parameters are valid. I can not find a way to check if a string(com_create_guid() returns string) is a valid GUID.

Upvotes: 29

Views: 25470

Answers (2)

Lewie
Lewie

Reputation: 547

There are a few rules that should be imposed on the UUID/GUID pattern.

  • The only valid letters are a, b, c, d, e, and f.
  • 0-9 can be replaced with the digit pattern \d
  • GUIDs are often case insensitive.
  • You either have {both brackets}, or none at all.

Simplified patterns

  • hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh
  • {hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh}

Expression:

var_dump(
preg_match("/^(\{)?[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}(?(1)\})$/i", $guid)
? "ok", "not ok");

Translation:

  1. / beginning of expression
  2. ^ beginning of string
  3. (\{)? optional opening bracket {
  4. [a-f\d]{8} 8 hex characters hhhhhhhh
  5. (-[a-f\d]{4}) 4 hex characters proceeded by dash -hhhh
  6. {4} previous pattern repeated 4 times
  7. [a-f\d]{8} 8 hex characters hhhhhhhh
  8. (?(1)\}) if first pattern was present {, then match closing tag }
  9. $ end of string
  10. / close expression
  11. i ignore case sensitivity

Upvotes: 48

Pascal MARTIN
Pascal MARTIN

Reputation: 401032

Considering a GUID is defined as something like this : "A98C5A1E-A742-4808-96FA-6F409E799937" (from what the wikipedia page says)

I suppose using a regex like this one would do :

$guid = 'A98C5A1E-A742-4808-96FA-6F409E799937';
if (preg_match('/^\{?[A-Z0-9]{8}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{12}\}?$/', $guid)) {
  var_dump('ok');
} else {
  var_dump('not ok');
}

It will match for

  • 8 characters (both letters and numbers)
  • 4 characters
  • 4 characters
  • 4 characters
  • 12 characters

Each set of characters being separated by a '-'


Considering you're using com_create_guid, the regex check for optionnals } and { arround the guid, which means this would display 'ok' too :

$guid = '{A98C5A1E-A742-4808-96FA-6F409E799937}';
if (preg_match('/^\{?[A-Z0-9]{8}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{12}\}?$/', $guid)) {
  var_dump('ok');
} else {
  var_dump('not ok');
}

Upvotes: 37

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