Patterns and Regex

Patterns & Regex

The regex rule matches a value against a regular expression — either an inline body or the name of a pattern you registered.

Inline regex

Pass the regex body without delimiters. The value is matched anchored as ^(...)$, so the whole value must match.

use InitPHP\Validation\Validation;

$v = new Validation(['code' => 'AB12']);
$v->rule('code', 'regex([A-Z]{2}[0-9]{2})');   // passes

Commas are argument separators. An inline body containing a comma — such as [a-z]{2,4} — is split before it reaches the regex engine. Register it as a named pattern instead (below).

Named patterns

Give a pattern a name once and reference it by name. Names are matched case-insensitively and persist across validation() runs.

$v->pattern('product_code', '[A-Z]{2}-[0-9]{4}');
$v->rule('sku', 'regex(product_code)');

pattern(string $name, string $body) adds or overrides a named pattern. The body has no delimiters and is matched as ^(...)$.

Built-in patterns

These names are available to regex out of the box:

Name	Matches
uri	URI path characters
slug	URL slug characters (letters, digits, -, _)
url	URL characters
alpha	Unicode letters
words	Letters and whitespace
alphanum	Letters and digits
int	Digits
float	Digits, dot and comma
tel	Phone-number characters (0-9 + space ( ) -)
text	Common prose characters
file	A file name with an extension
folder	A folder name
address	Street-address characters
date_dmy	d-m-Y style dates
date_ymd	Y-m-d style dates
email	A basic e-mail shape

$v->rule('handle', 'regex(slug)');     // "my-blog-post_2" passes
$v->rule('phone', 'regex(tel)');

regex vs the dedicated rules

For common cases, prefer the purpose-built rule over a raw pattern — they are clearer and handle edge cases (types, filter_var) for you:

Instead of	Prefer
regex(email)	mail
regex(int)	integer
regex(alphanum)	alphanum

Reach for regex when you need a shape the built-in rules do not express.

Next

• Rules Reference — the regex rule entry.
• Callable & Custom Rules — for logic regex cannot express.