Validating a Date

[Phear46]

OK, so i want my form adds a persons details to a DB, all good so far but i want to grab a birth-date with the form then input that to my DB. mySQL only accepts yyyy-mm-dd format so i need to convert my string to that format no-matter what.

 

But what if the person doesn't enter the date correctly? what if the date doesn't even exist?

 

I could 'guide' the user into inputting into the form in the correct format but Ive never seen this done on line anywhere. Everywhere ive ever enter a date has always accepted:

 

dd-mm-yy

dd-mm-yyyy

mm-dd-yy

mm-dd-yyyy

 

I can probably figure out formatting to mySQL format by myself but im totally confused by what i should do when the user enters a date like:

01-03-88

is this 1st March 1988 Or 3rd January 1988?

 

Is there a setting i can grab from the browser to determine where in the world a user is?

 

[mac_gyver]

don't give the user a choice on how to enter the date. use three specific select/option menus for the year, month, and day (add a date picker pop-up if desired to set the three select/option values.) then all you need to do is make sure the entered date is an actual date.

[Phear46]

been thinking that since i posted.... probably a much better/easier way of doing it!

[CrossMotion]

the strtotime() function mostly gets it right. but I agree with mac_gyver. use a date picker or at least drop-down menus for day, month, year to be 100% safe.

[buzzycoder]

Might this snippet will help you :

<?php
$date = '2003-04-31';
if(preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/', $date)){
    echo 'Valid';
}else{
    echo 'Not Valid';
}
?>

[requinix]

Might this snippet will help you :

<?php
$date = '2003-04-31';
if(preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/', $date)){
    echo 'Valid';
}else{
    echo 'Not Valid';
}
?>

 

If you do it that way (with a fixed format, contrary to the requirements) do a preg_match() for the basic format then a checkdate for the real validation. Writing a regex for all valid dates is pretty complex.

[buzzycoder]

Yeah,that would be helpful too.Thanks requinix,for pointing me out.

[Phear46]

All good suggestions guys, gone with drop downs for now as it seems the most basic way. Here is the code im using to draw the menu:

	<select name="day">
		<?php for ($d=01; $d<=31; $d++) {echo "<option value='$d'>$d</option>";}?>
	</select>
	<select name="month">
		<?php for ($m=01; $m<=12; $m++) {echo "<option value='$m'>$m</option>";}?>
	</select>
	<select name="year">
		<?php for ($y=date("Y"); $y>=1970; $y--) {echo "<option value='$y'>$y</option>";}?>
	</select>	

The only issue im having is that the values are coming up as '1, 2, 3, 4' etc etc instead of '01, 02, 03, 04' Is there a way i can force the counter to be at least two digits? I could check values when i process the form but it seems more logical to get this sorted with the actual form values that are submitted.

[buzzycoder]

This might help you :

<select name="day">
		<?php for ($d=01; $d<=31; $d++) { $d = sprintf("%02d", $d); echo "<option value='$d'>$d</option>";}?>
	</select>
	<select name="month">
		<?php for ($m=01; $m<=12; $m++) {$m = sprintf("%02d", $m); echo "<option value='$m'>$m</option>";}?>
	</select>
	<select name="year">
		<?php for ($y=date("Y"); $y>=1970; $y--) {echo "<option value='$y'>$y</option>";}?>
	</select>

[DavidAM]

I could check values when i process the form but ...

You absolutely must check the values when the form is submitted. It is a trivial matter for a user (i.e. bad guy) to send any data they want regardless of the values (OPTIONS) in your SELECT list.

[kicken]

I could 'guide' the user into inputting into the form in the correct format but Ive never seen this done on line anywhere. Everywhere ive ever enter a date has always accepted:

Requesting a particular format is generally what I do. Now days I use the new type="date" input + some JS to make it more compatible. In the past I've done separate select boxes or just a text note describing the required format.

 

I've seen such things fairly often out on the web, even some sites that are so strict they reject a date if you don't add leading zeros (ie, 05/01/13 would be ok, but 5/1/13 would be invalid).

[Barand]

strict or just plain sloppy?