Is there any short hands for user input validation in php?

Question

for example, I have a register function, that need the user input their "user name", "email address", and "password".

I need to check all the parameter from the user, which is not null, furthermore, I need check their input length that is short enough to store in the db. Moreover, I need check is there any duplicated user name and email in the db. Also, I need to check the email address is a valid email format.

Only create a simple enough register function, I need do so many checking. Is there any short hands for checking some basic stuff? for example, which is not null to increase the productivity.

Answer 1

You need to check it all because it can't check itself.

PHP has a number of useful functions to assist...

isset()

isset() to ensure the GET / POST variables are set. These missing are generally only caused by people tinkering.

Example

if ( ! isset($_POST['email'])) {
   $this->addError('You did not supply your email');
}

trim() and empty()

trim() and empty() for making sure someone entered some text other than whitespace. Note that empty() is a construct and must be called on a variable, not the string returned by trim() directly (my guess because it wants to examine a block in memory, not a value on the stack).

Example

$email = trim($_POST['email']);

if (empty($email)) {
   $this->addError('You didn\'t type any non whitespace characters');
}

Of course, use a better error that your end users will understand.

This is also used so often you could make a utility function that does this.

filter_var()

You can use filter_var() for validating things, such as validating emails, IPs and integers.

Example

if ( ! filter_var($email, FILTER_VALIDATE_EMAIL)) {
   $this->addError('You did not enter a valid email');
}

Regular Expressions

Regular Expressions can do a lot by themselves, such as checking for valid characters, patterns and lengths.

Example

if ( ! preg_match('/^\w{4,12}\z/', $username)) {
   $this->addError('You did not enter a valid email');
}