Quickly Validate Form Fields in PHP

Question

When I have fields under a form tag, I use isset() function such as below:

if(isset($_POST) and isset($_POST['title']) and $_POST['date'])
{
   //something;
}

and it gets bigger when I validate more fields. I am looking for any easy way of validate whether they are all filled or not in server-side with PHP.

Maybe something which navigates all the fields and check whether they are filled as required.

Answer 1

A more reusable solution would be to write a small function to verify a list of keys exist, such as

function array_keys_exist($keys, $search) {
    // If we were passed a single key, use existing function
    if (!is_array($keys)) {
        return array_key_exists($keys, $search);
    }
    // If there are no keys in $search that are not in $keys
    // We have all the keys
    return 0 == count(array_diff($keys, array_keys($search)));
}

which could then be used for all your forms like this:

$requiredFields = array('title', 'date', 'details');
if (array_keys_exist($requiredFields, $_POST)) {
    // Do your thing
}

Frankly, I'm not sure why this isn't already a built-in function

Answer 2

<?php

$fields = array('field1', 'field2', 'field3', ...etc...); //  Array of fields

$valid = true;  //Assume all fields are correct and set this to false if not

foreach($fields as $field) {
    if(!array_key_exits($field, $_POST)) { 
        $valid = false; // At least one key isn't set
        break;
    }
}

if($valid) {
    // All fields are good
} else {
    //Your user failed...
}

Answer 3

// required fields
$fields = array('title', 'date', 'email');

// optionally ignore blank posted values
$_POST = array_filter(array_map('trim', $_POST), 'strlen');

if (count(array_intersect_key($_POST, array_flip($fields))) == count($fields))
{
    // all the required fields were posted
}

else
{
    // ...not
}

Answer 4

$_POST is an array, so you can fetch its element using foreach and then test each element if it is empty or no, collecting errors if there and at the end send one error message.

Answer 5

I've found it amongst comment section on PHP Manual...

A little function which take an array as keys:

<?php
//note the s in the function name (keys)
function array_keys_exists($array,$keys) {
    foreach($keys as $k) {
        if(!isset($array[$k])) {
        return false;
        }
    }
    return true;
}
?>
//useful to validate a form for example
<form>
    <input type="text" name="field1" /><br />
    <input type="text" name="field2" /><br />
    <input type="text" name="field3" /><br />
    <input type="text" name="field4" /><br />
    <input type="text" name="field5" /><br />
</form>
<?php
if(!array_keys_exists($_POST,
array("field1","field2","field3","field4","field5")
)) {
    //some fields are missing, dont do anything (maybe hacking)
} else {
    //code ...
}
?>