Fatal error: Uncaught PHP exception in DateTimeZone::__construct()? - php

Question

This is going to be a bit difficult to explain but I will try my best to explain it as good as i can.
I am passing Data from an input textfield on one page (page1.php) to a Select form on another page (page2.php).
This works as should.
the Select Form contains some PHP timezones and when a timezone is selected, the page page will echo the current time for that timezone.
This also works as it should.
The problem is when I enter a timezone name in the input textfield on (page1.php) , it will show the name in the Select Form on (page2.php) BUT it will not echo its current time and it will throw out this error:
Fatal error: Uncaught exception 'Exception' with message 'DateTimeZone::__construct(): Unknown or bad timezone (London)' in page2.php:16 Stack trace: #0 on line 16.
when infact the timezone London exists in the Select Form Options and if I enter/search for London directly in the select form, it will echo the current time for that timezone but it will NOT if the timezone name was entered in the input textfield on page1.php and it was passed to the select form on page2.php!
here is what I have on page2.php:
<?php
if( isset($_POST['submit']))
{
//be sure to validate and clean your variables
$timezone2 = htmlentities($_POST['timezone2']);
//then you can use them in a PHP function.
function get_timezone_offset( $remote_tz ) {
$timezone2 = new DateTimeZone ( $remote_tz ); ----->>> Line 16 is here.
$datetime2 = new DateTime ("now", $timezone2);
$offset = $timezone2->getOffset($datetime2);
return $offset;
}
$offset = get_timezone_offset($timezone2);
}
?>
<?php
$options = array();
$options[$_POST["location"]] = $_POST["location"]; <<<<<<----- Data from input textfield on page1.php
$options["Africa/Addis_Ababa"] = "Addis Ababa"; <<<<<<----- Select Form Options
$options["Europe/London"] = "London"; <<<<<<----- Select Form Options
?>
and here is the Select Form on page2.php
<form id="myForm" name="myForm" class="myForm" method="post" action="page2.php">
<select style="font-size:9px;" name="timezone2" id="timezone2" class="timezone2">
<?php
foreach($options as $key => $value)
{
echo '<option value="'. $key .'" label="'. $value .'">'.$value.'</option>';
}
?>
<option value="<?php echo $_POST["location"]; ?>"><?php echo $_POST["location"]; ?></option>
</select>
</div>
<div id="myBtn" style="position:relative; float:left; width: 228px; margin-top:50px; margin-left:350px;"><input type="submit" name="submit" id="submit" class="submit" value="Search"/></div>
</form>
and here is the input textfield on page1.php
<form method="post" action="../page2.php">
<input name="location" type="text" value="Search"/>
<button type="submit">Search</button>
</form>
could someone please point me in the right direction?

Answer 1

You're going about this wrong for a few reasons. Firstly, the list of possible timezones is finite so get rid of the text field and just use a dropdown.
Second, you can remove\rename the items in the dropdown all you want but just remember that since you are saving the offset and not the tz name you can never go back (my example will show you exactly why that is if you play with it). Usually, it is best to store the name and not the offset so that you can manage daylight savings properly. You'll notice that to get this system to work I need to call date('I') to find out if it is daylight savings which is really bad (just because it's daylight saving in my server TZ doesn't mean it is in the users TZ). If you saved the TZ name instead you could defer that logic to PHP and just use whatever offset it currently is. This may not seem important in this simplistic example but if you ever tried to store that offset or calculate future\past times using it you'll definitely have troubles.
One other tiny thing is that it is odd to put function definitions inside of 'if' statements. In PHP all function definitions are global so it will be available regardless of whether the 'if' condition is true. The problem with doing that is now you've obscured your logic with no gain. It is easier and clearer to put that elsewhere.
I've rewritten your code to be a little nicer and to actually work as you are using it but I've left out a few details (like aliasing the TZ names [which you seem to have a handle on how to do] and switching to using TZ names instead of offsets [because that may break other code you have]) but I encourage you to fix those as well.
<?php
$tz_offset=0;
function get_offset_time($offset=0) {
$original=new DateTime("now");
$timezoneName=timezone_name_from_abbr("", $offset, date('I'));
if(!$timezoneName) die('ERROR: Unknown timezone \''.($offset/3600).'\'');
$oTZ=new DateTimezone($timezoneName);
$modified = $original->setTimezone($oTZ);
return $modified->format('Y-m-d H:i:s');
}
function get_timezone_offset($tz_name=null) {
if(!$tz_name) return 0; // If we have invalid data then return before we error
$tz=new DateTimeZone($tz_name);
$dt=new DateTime("now", $tz);
return $tz->getOffset($dt);
}
function enumerate_tz($tz_select=null) {
global $tz_offset;
$tz_ident=DateTimeZone::listIdentifiers();
foreach($tz_ident as $val) {
$tmp_offset=get_timezone_offset($val);
if($val=='UTC'||$tmp_offset)
echo '<option value="'.$val.'" '. ($tmp_offset==$tz_offset?' selected':''). '>'.
$val. ' [ '.($tmp_offset/3600).' ]'. // If you'd like to customize the viewable names for each TZ you may do so here
'</option>';
}
}
if(isset($_POST['tz_input']) && $_POST['tz_input']) {
$tz_input=htmlentities($_POST['tz_input']);
$tz_offset=get_timezone_offset($tz_input);
}
echo '<html><title>Timezone Select</title><body>'.
'<p>The current timezone offset is: '. ($tz_offset? ($tz_offset/3600): '0'). '</p>';
echo '<p>The current time is: '. get_offset_time($tz_offset). '</p>';
echo '<form method=post><select name=tz_input>';
enumerate_tz($tz_offset); // You'll notice that this list duplicates many of the timezones so that after selecting one the next
// time through it'll often select a different one. If you want to fix that you'll need to save the actually offset name instead of an offset.
echo '</select><input type=submit value=Search />'.
'</form></body>';
?>
EDIT: One other thing to note is that PHP's timezone_name_from_abbr() function is not complete. Some timezone offsets will not return a TimeZone name. You must account for that as well. For example, even though PHP understands the 'Pacific/Midway' timezone it cannot find it when doing a reverse lookup. I've updated the code so that won't cause a hard error anymore.
EDIT2: I can see that you aren't going to be happy until someone shows you how to shine that turd. Here you go:
function getOptionDX($val, $option_array) {
if(!isset($option_array)||!is_array($option_array)||!count($option_array)>0||!$val) return null;
$val=htmlentities($val);
if(isset($option_array[$val])) return $val;
$new_val=array_search($val, $option_array);
return $new_val!==FALSE?$new_val: null;
}
Add this to your code and replace the call to htmlentities with a call to this:
$timezone2 = getOptionDX($_POST['timezone2'], $options);
Lastly, change this line:
if($timezone2) $offset = get_timezone_offset($timezone2);
If the user enters the TZ manually and it is correct then skip page2.php. This is as close to an answer as can be given if you don't want to change anything. The fact is that your logic is flawed in the first place (that is not meant to be a jab but it is true).
EDIT3: IDK what was wrong but here is my full code listing with the fixes you asked for:
<?php
$offset=0; $timezone2='';
$options = array();
$options["Africa/Addis_Ababa"] = "Addis Ababa";
$options["Europe/London"] = "London";
$options["America/Chicago"] = "The Windy City";
function getOptionDX($val, $option_array) {
if(!isset($option_array)||!is_array($option_array)||!count($option_array)>0||!$val) return null;
$val=htmlentities(ucwords(strtolower($val)));
if(isset($option_array[$val])) return $val;
$new_val=array_search($val, $option_array);
return $new_val!==FALSE?$new_val: null;
}
function get_timezone_offset( $remote_tz ) {
$timezone2=new DateTimeZone($remote_tz);
$datetime2=new DateTime("now", $timezone2);
$offset=$timezone2->getOffset($datetime2);
return $offset;
}
if(isset($_POST['location'])) {
$addLoc=getOptionDX($_POST['location'], $options);
if(isset($addLoc)) $options[$addLoc]=$_POST['location'];
else header('Location: '. $_SERVER['SCRIPT_NAME']);
}
if(isset($_POST['timezone2'])) {
$timezone2=htmlentities($_POST['timezone2']);
$offset=get_timezone_offset($timezone2);
}
if(isset($_GET['page2'])) {
?>
<form method=post action=?page2>
<select name=timezone2>
<?php foreach($options as $key=>$value) echo "\t".'<option value="'. $key .'"'.(get_timezone_offset($key)==$offset?' selected':'').'>'.$value.'</option>'."\n"; ?>
</select>
<input type=hidden name=location type="text" value="<?php echo $_POST['location']; ?>"/>
</div>
<input type=submit value=Search>
</form>
<p>Current Offset: <?php echo $offset/3600; ?></p>
<p>Current Time: <?php echo gmdate('Y-m-d H:i:s'); ?> UTC</p>
<p>Current Time: <?php echo gmdate('Y-m-d H:i:s', time()+$offset).' '. $timezone2; ?> </p>
<?php
} else {
?>
<form method=post action=?page2>
<input name=location type=text value=""/>
<button type=submit>Search</button>
</form>
<?php
}
?>
I've tested this and know it works, if that isn't enough to answer your question then I give up. I'm starting to think that you really want a way to invent new timezones which don't exist. That isn't possible. You can alias those which already exists as I've done here which is as close as you're ever going to get. Logically, time zones can only range from -12:00 to +12:00 and nearly every known timezone is already accounted for so you really have no choice but to rethink your design if this isn't enough.