Form Validation Tips For All! Part One.

[jadedknight]

I hope this is the right forum to post this in.

Ok guys and gals. I have read these forums a lot looking at posts and gaining a lot of information about PHP. I just want to give something back. When I begin writing code I always wonder if it's the most efficient way to write it, and if it is using proper semantics. So I purchased the PHP Cookbook http://www.oreilly.com/catalog/phpckbk/ and I wanted to share some of the code with you. All these code snippets have to do with form validation and processing because that is one of the most popular subjects of PHP. I don't want to rip off the book so I will post the code but try and write my own descriptions. Please enjoy!

 

First thing I would do is take a look here http://www.php.net/manual/en/language.basic-syntax.php at advanced escaping, I never knew you could write PHP split up like that!

Problem: You want to use the same page to process and emit a form.

 

<?php if ($_SERVER['REQUEST_METHOD'] == 'GET') { ?>
<form action = "<?php echo $_SERVER['SCRIPT_NAME'] ?>" method = "post">
What is your first name?
<input type = "text" name = "first_name" />
<input type = "submit" value = "Say Hello" />
</form>
<?php } else {
echo 'Hello, ' . $_POST['first_name'] . '!';
}
?>

 

Problem: Make sure a value has been supplied in a form.

 

<?php
if (! strlen($_POST['flavor'])) {
print 'You need to supply a value!';
}
?>

** OR **

Strict validation for empty fields.

<?php
if (! (isset($_POST['flavor']) && strlen($_POST['flavor']))) {
print 'You must enter a value!';
}
?>

 

Problem:Looking for a digit in a form NOT a letter.

 

<?php
if (! ctype_digit($_POST['age'])) {
print 'Please enter a digit!';
}
?>

 

Heres a gem.

Problem: Valid e-mail required!

 

<?php function is_valid_email_address($email){
$qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
$dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
$atom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c' . '\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
$quoted_pair = '\\x5c[\\x00-\\x7f]';
$domain_literal = "\\x5b($dtext | $quoted_pair)*\\x5d";
$quoted_string = "\\x22($qtext | $quoted_pair)*\\x22";
$domain_ref = $atom;
$sub_domain = "($domain_ref | $domain_literal)";
$word = "($atom | $quoted_string)";
$domain = "$sub_domain(\\x2e$sub_domain)*";
$local_part = "$word(\\x2e$word)*";
$addr_spec = "$local_part\\x40$domain";
return preg_match("!^$addr_spec$!", $email) ? 1 : 0;
}

if (is_valid_email_address('hello@hello.com')) {
print 'Valid';
} else {
print 'Not Valid';
}
?>

 

Anyways this is form validation part one. More parts coming soon!! I hope I help. Btw! I REALLY reccomend this book, I just purchased it tonight it's great. Very practical code examples.

[Greaser9780]

I recently purchased the same book. I like the way it breaks down in chapters and then is problem specific. Once you nail down what the problem is this book shows you how to solve it.