how to validate a date based on user input from a form

[webdeveloper123]

Hi Guys,

My question is if I am doing something like this:

$customers['first_name'] = $_POST['fname'];
$customers['last_name'] = $_POST['lname'];


$errors['first_name']  = is_text($customers['first_name'], 2, 20)   ? '' : 'Must be 2-20 characters';
$errors['last_name']  = is_text($customers['last_name'], 2, 20)   ? '' : 'Must be 2-20 characters';

How would I validate a date? There seems to be a function called checkdate and validatedate is mentioned (although no longer on php.net) so It must have been taken out.

Btw, the date is not known before hand, as it's coming from a form which asks for users birthdate.

Many thanks

 

[kicken]

You could use something like DateTime::createFromFormat() to try and parse the date.  If it fails to parse, invalid format.  If a valid date is created, you'll need to check it matches the input by comparing the input to the formatted date.  This is because the function will "fix" invalid dates, for example 07/35/2022 would parse as 08/04/2022.

<?php

$input = '07/31/2022';
$date = DateTime::createFromFormat('m/d/Y', $input);
if (!$date || $date->format('m/d/Y') !== $input){
    echo 'Invalid date';
} else {
    echo 'Valid date';
}

Any validate beyond that depends on what you need from the data.  For a birthday for example, you might validate it's in the past and not in the future. 

[webdeveloper123]

can I not do something like this, if all I want to do is make sure it is actually a valid date, nothing more

$errors['birthdate']  = checkdate($customers['birthdate']) ? '' : 'Not a valid date';

 

[webdeveloper123]

actually checkdate needs 3 parameters so that won't work

[webdeveloper123]

is there something like checkdate which will take 1 argument as a variable or as $customers['birthdate'] and see that the date is valid? Im looking around and can't fine one

[Barand]

10 minutes ago, webdeveloper123 said:

is there something like checkdate which will take 1 argument as a variable or as $customers['birthdate'] and see that the date is valid?

Adapt @kicken's code

function check_date($input, $format='m/d/Y')
{
    $date = DateTime::createFromFormat($format, $input);
    return ($date && $date->format($format) === $input);
}

if (!check_date($input) ) {
    $error['date'] = 'Invalid date';
}

 

[webdeveloper123]

17 hours ago, Barand said:

$format='m/d/Y

In my database I'm saving as 'Y-m-d' so would I update that line to reflect this?

Edited July 25, 2022 by webdeveloper123

[Barand]

No. It is the expected input format that is being defined here.

Consider changing the function thus

function check_date($input, $format='m/d/Y')
{
    $date = DateTime::createFromFormat($format, $input);
    return ($date && $date->format($format) === $input) ? $date->format('Y-m-d') : false;
}

It then returns "false" if the date is invalid but returns the date in Y-m-d format if valid.

[webdeveloper123]

thanks barand