Key

v::key(string $name)
v::key(string $name, v $validator)
v::key(string $name, v $validator, boolean $mandatory = true)

Validates an array key.

$dict = array(
    'foo' => 'bar'
);

v::key('foo')->validate($dict); //true

You can also validate the key value itself:

v::key('foo', v::equals('bar'))->validate($dict); //true

Third parameter makes the key presence optional:

v::key('lorem', v::string(), false)->validate($dict); // true

The name of this validator is automatically set to the key name.

See also:

Attribute